|
Archive-name: autos/vw/performance-faq
Rec-autos-vw-archive-name: performance-faq Posting-Frequency: bi-monthly Last-modified: 1 December 1995 See reader questions & answers on this topic! - Help others by sharing your knowledge
----------------------------------------------------------------------
Frequently Asked Questions
for
Water Cooled VWs
-- Performance --
rec.autos.vw
Date:
Version:
1 Feb 94 = Creation and copy from tech faqs.
1 Mar 94 = First posting.
1 Apr 94 = Conversion to MsWord for easier maintenance.
1 May 94 = Solo I & II added. Books to read.
1 Jun 94 = Relocating batteries, shock stiffness table,
lights, alignment
15 Jun 94 =performance updates, Sound insolation.
1 July 94 =Edits, stressbar updates.
12 Oct 94 = Lots of new stuff.
27 Jan 95 = Partially updated
10 Feb 95 = Finally included Mark's additions.
1 Oct 95 = Updated distribution, formatting.
1 Dec 95 = Updates (note formatting is a bit screwed up)
Moderator: Jan Vandenbrande, jan@ug.eds.com
See also the list of contributors at the end.
Please feel free to submit any additional info.
------------------------------------------------------------
Copyright Notice (c) -- 1994, 1995: All Rights Reserved
The information contained here is collectively copyrighted
by the authors. The right to reproduce this is hereby
given, provided it is copied intact, with the copyright
notice inclusive. However, the authors explicitly prohibit
selling this document, any of its parts, or any document
which contains parts of this document.
------------------------------------------------------------
Index:
======
GENERAL 1
Q: I want to go faster? Where should I start?1
Q:I'm interested in eventually changing from autox to obtain the SCCA
Competition license on and do some amateur weekend racing?. 2
Q:What type of car racing are available (for normal mortals) in the US?
2
Q: What is autocross (Solo II)?2
Q:What are the allowable mods for each auto-x category? 4
Stock: 4
Street Prepared: 4
Prepared: 5
Modified 6
Q: What are the Solo II Classifications for VWs?7
Q:What are the addresses for some of the performance related clubs?7
Q:What are the some of the performance driving schools? 7
Q: Will performance equipment void my car warrantee?8
CHEMICALS 8
Q: What is Rain-X? Does it work?9
Q: Can and should I use synthetic motor oils?9
Q: Is synthetic oil compatible with other oils.10
REFERENCE MATERIAL 10
Q: What are some of the Performance books to Read?10
Q:Whar are some of the Monthly/Quaterly Publications? 11
ENGINE 11
Q: How can I get more power out my VW?11
Q: What's a K&N air filter?15
Q: How do I service a K&N air filter?15
Q: How do I keep my engine cool?15
Q:How can I improve heat transfer/what are alternative coolant fluids?
16
Q:Do "Split Fire" (= name of a plug sold in the US, not a type of plug)
plugs live up to their advertised claims? 16
Q: What net wisdom exists on exhaust systems?17
Q:Removing the restrictor in a VW Fox to get more power? 17
Q:What is the relationship between torque and horsepower?17
Q: Should I remove the catalytic converter?18
Q:Are the performance chips interchangeable between cars with similar
engines, e.g., VR6 Corrado and Passat? 18
Q: Which performance chips are recommended for VWs?18
ELECTRICAL 18
Q:How can I improve night visibility/increase light output? 18
TRANSMISSION 19
Q: Should I change to a racing clutch?19
Q:What transmission fluid should I use (manual cars)? Why is it
important for racing? 20
Q:What's the difference between the normal wheel bearing grease and
Spectro SPL grease? 20
BRAKES 21
Q: What and why vented rotors?21
Q: Why cross drilled rotors?21
Q:Is it worthwhile changing my rear drums to disc brakes?21
Q:What are the benefits of steel braided brake lines? 21
Q: What pads should I use?22
TIRES/RIMS/SUSPENSION 22
Q:I want to improve the handling of my VW? Where should I start? 22
Tires & Rims: 22
Q: What are the rim width ranges per tire size?23
Q:What is the largest rim/tire sizes that will fit on my VW? 23
Q:What is rim offset? [D="EinpressTiefe" or "ET" Value] 24
Q:What are the "standard" VW wheel offsets (the amount the rim is offset
from the hub)? 24
Q:What is the proper tire inflation for my car for performance driving?
24
Q: What are examples of proper tire inflation autoX?25
Q:How can adjust over/under-steer behavior of my car? 26
Q:My VW lifts its rear inner wheel in sharp turns. Is this normal? 26
Q: Are VW rims interchangeable?26
Q:What are the current preferred tire choices for VWs? 27
Normal 27
Snow 27
Perfomance 27
Race 28
Q:What are "standard" (factory) tire sizes for my VW? 29
Q:How can I tell the characteristics of a tire by just looking at it?
30
Q: Will wider tires help my performance?30
Q: What is a performance alignment?31
Q:What does toe-in, caster and camber mean and how do they affect the
car's handling? 31
CAMBER: 31
TOE: 32
CASTER: 33
Q:My stock shocks are shot? What should I use to replace them with?34
Shock valving comparison chart 35
Q:How can I make my car quieter? What kind of sound insulation is
available? 39
Q: Is moving my battery to the trunk a good idea?
What effect will it have? 40
GENERAL
Editor's Foreword: This FAQ is geared at improving the
performance of watercooled VWs based on the Golf Chassis (A1-
A3: Golf I/Rabbit, Golf II & III, Sciroccos, Corrados,
Jettas, Ventos, Convertibles) using predominantly the "1600
type" and larger 4 cylinder engine block and the new VR6
2.8/2.9l engine. Because of this FAQ's origine, most
improvements are aimed at the US/Canadian market. The above
cars also share many components with Dashers/Passats/Fox's
(e.g., engines), though they differ in many other aspects
such as suspension and exhaust system. Some of these cars
may actually have more in common with Audis.
Performance improvements encompasses a wide field of
subjects, most commonly referred to in the context of
increasing power and improving handling. This FAQ intends to
go beyond these traditional meanings and include changes
that improve upon the stock design. Performance often is
achieved at the expense of something else often not
mentioned with the advertised component such as fuel
consumption, harsher ride or noise. This FAQ intends to
reveal some of these as well.
One of the things to keep in mind is cost. In some cases the
improvements will costs as much as a new stock part from VW,
but in other cases it costs more. Generally you will never
recover the cost of these improvements. Unlike real estate,
most cars are not investments and therefore the reason for
spending money is for pure pleasure. For that reason, you
need to make a decision on whether it is worth it to you for
the amount of time you want to keep the car. Also, it makes
little sense to buy the most expensive suspension system if
your engine is about to blow. Fix the rest first perhaps
with better components.
Not covered in this FAQ are the engines/fuel systems
available outside North America such as engines less than
1500 cc and carburetors/mono-throttle FI systems.
Another good thing to keep in mind is: "Speed costs money,
how fast can you afford to go?" [?]
Q:I want to go faster? Where should I start?
A:Yourself. Most people only utilizes a small portion of
their car's capabilities, and often do not know how the
car handles under emergency conditions. Almost EVERYONE
can benefit by taking a performance "Driving School" from
one of the local clubs (e.g. SCCA, ~1/2 day, inexpensive,
fun) or from a performance driving school (e.g. Skip
Barber, Bob Bondurant, etc, expensive, fun). It is
probably the biggest single improvement you can make and
it's a skill you take with you no matter what car you are
driving.. In every day driving it may make the difference
between an accident and avoiding one!
The next question you need to ask yourself is *why* you
want to improve your car's performance. Do you want to
impress your friends? Do you want to blow away other cars
on the street? Do you want to compete, and if so, what
type of competition? There are all kinds of car
competitions: Autocross, road racing, rally, concours,
drag race, and so on?
Will you be using this car for your daily commute or will
it be purely used for competitions? Depending on what
you want to do, you may want to follow a very different
path to enhance performance.
What runs well on a track may not be acceptable or barely
drivable for a street car (clearance, noise, hard ride,
rough idle, bent rims, the law...). Additionally, if you
want to race in a club, cars are categorized depending on
their power and handling, and to what extent they have
been modified.
For example, it may be better to leave your car stock
than to make certain modifications. Most classing
structures allow only certain modifications, and if you
do somethign else, you'll be bumped to the next category.
For instance, in SCCA Solo II autocrossing, Stock-
category cars must run on rims that are the same size as
the originals. If you go with a wider rim, you will have
to run in the Street Prepared category. There, you would
also have to lower and stiffen your car and replace your
entire intake system in order to be competitive.
Q:I'm interested in eventually changing from autox to
obtain the SCCA Competition license on and do some
amateur weekend racing?.
A:I'd suggest starting out in a Stock vehicle. An option,
if you really intend to eventually go road racing, is to
look for an inexpensive road racing vehicle like a Vee or
an IT car, and run it as an autocrosser while learning;
then when you're ready for SCCA racing school, you should
already have a reliable, well understood vehicle in your
possession. Note that it's *very* hard to learn to drive
in a formula car. People just starting in driving
competitions should be in two-seat sedan-type cars --
things happen more slowly, and they can take passengers
and ride as passengers with better drivers. Note that
formula racing is also a lot more expensive.
Q:What type of car racing are available (for normal
mortals) in the US?
A:The SCCA defined several types of racing, open to the
"public":
Solo I is a high speed event, using cars prepared to road
racing safety standards; it covers both hill climbs and
race track based events. Solo I (and Solo II) are time
trials; there is no wheel-to-wheel action involved.
Solo II is a moderate speed event; it corresponds roughly
to what other clubs call autocross. Safety equipment is
not mandated, except for roll bars in heavily prepared
convertibles (stock convertibles do not require roll bars
in Solo II.)
Q:What is autocross (Solo II)?
A:Autocrossing (or, Solo II) is timed racing in a
controlled situation where the agility of your car, and
your ability as a driver, are more important than raw
horsepower. Autox courses are usually setup in large
parking lots with orange traffic cones. Unless the course
is pretty long, only one car is allowed on the course at
any time, which means that there's no possibility of
going fender-to-fender with another car. Cars are
classed, either by the local group (if they're
independent) or by the Sports Car Club of America (SCCA),
according to their level of vehicle
preparation/modification called categories (Stock, Street
Prepared, Prepared and Modified, or S, SP, P, M) and by
their performance characteristics, i.e., class. There are
9 stock classes from SS (Super Stock) down to H Stock, SP
and M go from A-E, but P goes A-F.
There is a category that some SCCA regions are using
called SM or Street Modified (aka "Open Street Prepared"
in some regions). This is for cars that do not fit in
Street Prepared but are not competitive for Prepared
class. (Note that this is not a nationally recognized
class).
Stock class was originally intended to be a place for
novice autox-ers to "run what they bring", and many
local clubs have special classes for novice competitors
to compete in for their first year. The current
situation for the Stock Category is that it has become BY
FAR the most intense competition, followed by either
Street Prepared or Modified (depending whether you look
nationally or regionally).
The two other categories are Prepared (mostly race-
prepped production cars) and Modified (open wheel cars
and production cars with major engine transplants, etc.).
The preparation allowances for Stock Category are
somewhat more liberal than one might guess: any front
swaybar may be used, and adjustable suspensions are not
required to be adjusted to factory specs. As an example,
the VW GTI that I run typically is set to 2.25 degrees
negative camber and 3/16" toe out at the front. In
addition, you need autocross tires to be really
competitive, and these tires are worthless for any street
use. Most serious competitors in Stock Category buy a
second set of wheels and mount autocross tires. The above
notwithstanding, autocross competition is amazingly
challenging and fun, as long as you understand that you
won't be winning any trophies until you get some "seat
time". I highly recommend the activity.
At the beginning of the autox season most clubs also hold
novice driver and performance driving schools which teach
you the basics (how to follow the course, how cars are
staged on the grid, how to be a course worker, safety
issues, etc.). All you need to compete in most places is
a street-legal car that can pass a basic safety
inspection and a valid drivers license; you're required
to wear a helmet (Snell 75 or ANSI Z90.1b (1979)
approved) when you race, but there are usually loaner
helmets available for you to borrow when you're first
getting started. (Note: DOT only approved helmets are not
allowed).
There's an Internet-based group of autox-ers called
"Team.Net" (the "dot" is pronounced) who have a mailing
list and an ftp archive to promote discussion of autox-
related issues.
Send email to "autox-request@autox.team.net" or in case
of failure, use autox-request@triumph.cs.utah.edu (the
former hoosier address has been decommissioned) to be
added to the list. Their URL for WWW access is:
http://triumph.cs.utah.edu/team.net.html. They also have
a fairly extensive set of archives, pictures and mpeg
movies.
Also, call the SCCA ((303) 694-7222) and ask for the Solo
II contact person in your region; they should provide you
this person's phone number, and you can call this person
to find out when events are scheduled.
Contributors:
[Blake Sobiloff <sobiloff@lap.umd.edu>]
[jay.mitchell@the-matrix.com (Jay Mitchell)]
[Jonathan Dove <jdove@gsvms2.cc.gasou.edu>]
[Mark Sirota <mark@greenwich.com>]
Q:What are the allowable mods for each auto-x category?
A:There are four major auto-x categories: Stock, Street
Prepared, Prepared and Modified. It is relatively
important to avoid spreading the misconception that the
four categories are a linear progression -- they're not.
Modified is not for "production based cars that have been
modified beyond Prepared allowances," because that
suggests that Prepared is beyond SP, and Mod is beyond
Prepared. It's not so. It's better to think that there
are two progressions -- Stock -> SP -> Mod, and Stock ->
Prepared -> Mod. I generally phrase the Modified
description as "two for production-based cars that only
barely resemble their original configuration."
Stock:
Cars must run "as specified by the manufacturer," with
the exception of specific allowances. These allowances
include [jay.mitchell]:
1.The use of any front swaybar.
2.Any suspension adjustment IF the manufacturer makes
provision for adjustment for non-competition purposes.
3.Any shock absorber that is does not change suspension
geometry or alter the range of travel (i.e., must use
original mounting position). I [jay.mitchell] use Konis
on my A2 VWs, and the Nationals-winning cars have all
used Konis as well.
4.An aftermarket steering wheel within 1" total diameter of
the stock wheel. Wheels with airbags may not be changed,
and cars made after model year 1990 must retain the stock
steering wheel. <Note: this allowance may be withdrawn
soon>.
5.Road wheels of the stock diameter and width with offset
within +/- 1/4" of stock. This means that wheels with 6mm
less offset than stock are allowed, resulting in a track
width increase of 1/2"
For example, it allows wheels with 32mm offset on 8V GTIs
and Jettas (stock is 14x6 with 38mm offset), widening the
track by a total of 1/2".
6.Any brake lining material.
7.Certain engine "blueprinting" practices, although these
are rapidly being phased out. Balancing and blueprinting
is only allowed if done by the parts-bin technique; no
machining is allowed. Cars model year '92 and newer may
not overbore/balance, and all cars starting in 1/1/95
this is not allowed.
8.The use of any DOT-legal "street" tire. The hot setups
are BFG COmp T/A R1s or Yokohama A008RSIIs, and these
tires are stickier than pure racing rain tires were five
years ago! [Jonathan Dove]:
9.Ignition timing must be within factory setting
10Can change the exhaust system behind catalytic converter
(if equipped) or exhaust manifold.
11Allows the use of bolt in roll cages.
Other than the above modifications, you have to leave
your car pretty much as it was manufactured in Stock,
including the original driver's seat, body trim (you
could add non-aerodynamic appearance bits, but you could
NOT remove original trim), battery location and size,
except for loose items, such as the jack and spare tire
which may be removed.
Street Prepared:
(Basically the same as stock except for these)
Street Prepared was originally intended as an incremental
step beyond Stock prep levels. As it now stands, a really
competitive Street Prepared car may neither be street legal
nor practical for street use. (Note that older cars are
subject to less stringent EPA/NHTSA regulations and
therefore may be street legal in SP class). Tires must still
be DOT legal. In addition to Stock allowances, Street
Prepared allows the following:
1.Replacement or modification of stock springs. Replacement
springs must be of the same type (coil, leaf, or torsion
bar) and in the same location, as original, but the rate,
free length, and coil diameter may vary from stock.
2.Installation of camber plates in strut suspensions.
3.Installation of body stressbars. There are strict
limitations on the type of "strut brace" that may be
installed, but some of the most common ones (Neuspeed
front bars, for example) are legal.
4.The use of any wheel size and/or offset.
5 The use of any intake and/or exhaust system that will
attach to the original, unmodified engine, i.e., the
cylinder head may not be mcahined or drilled to accept a
non-stock manifold.
6 The alteration or removal of emission control devices.
7 The installation of any fully padded and upholstered
driver and front passenger seat.
8 The installation of any steering wheel.
9 The use of a limited slip differential with the same
factory ratio.
10The use of any flywheel, clutch, pressure plate, etc.,
that will bolt to the stock crankshaft.
11The use of any ignition system, including a crank fire
system on a car not originally so equipped.
12Ignition timing can be set outside factory specs.
Prepared:
Prepared Category is structured around SCCA club racing
preparation allowances for Production and GT class race
cars. Prepared cars typically have all interior trim removed
(not allowed in Stock or Street Prepared), roll cages, full
racing suspensions, highly modified engines, and they can
run on racing slicks. A list of allowances would be far too
long to itemize here, and you have to have both a Solo II
rulebook and the General Competition Rules to determine the
legality of any particular modification to a car.
The following was supplied by Richard Welty:
Production is a road race class; although stagnant for
many years, there is now change occuring here. the cars
in production are substantially
different from their road-going cousins.
GT: these are generally tube framed cars with sheet metal
that resembles a road going car; there are 5 classes, GT-
1 through GT-5. GT-1 contains corvettes, camaros, etc.,
and GT-5 contains things like Minis, and there are
various cars in between.
Sports Racers: these are single-seat, closed fendered,
special purpose race cars. there are a number of
subclasses which are quite different from each other:
Sports 2000, C Sports Racer, D Sports Racer, Spec Racer,
Shelby Can Am, and so forth...
Formula Cars: these are the single seat, open fendered,
special purpose race cars. like sports racers, there is a
lot of variation in the subclasses, which include:
Formula V (based on air cooled VW parts), Formula 440
(based on 2 stroke motors and CVTs), Formula Ford (based
on 1600cc Ford motors), Formula Continental (a
conglomeration of various older winged Formula cars), and
Formula Atlantic.
Showroom Stock: a class where theoretically stock
vehicles of recent vintage come together and do
experiments in clever, difficult to detect cheating.
Supposed to be cheap, but ends up being expensive.
A more elaborate entry by Bob April: SCCA has a form of
racing, Showroom Stock, that purports to be exactly that.
Outside of a roll cage, fire extinguisher, and
competition harness, the car is supposed to be dead
stock. Even the adjustments (such as front wheel camber)
must be set to factory specs. Cars must be relatively
new. In my experience (some years back) 1/3 of the cars
were legal, 1/3 had fudges which probably didn't matter,
and 1/3 cheated like hell. You can be in the first third
(I was) and still have fun. You get to race at places
you see on TV (Watkins Glen, Road America, etc.) I drove
the car to the track, put numbers on with contact paper,
and had a ball. In circa 50 races I had to get the car
towed from the track three times (one head gasket, one
destroyed clutch, one large hole in engine block with rod
sticking out), although I also once drove an X1/9 back
400 miles in 3rd gear (only), towing a small trailer with
race tires and tools. The driver must join SCCA, have a
routine physical, and have a helmet, firesuit, and
gloves. Figure $1000-$2000 to prepare car and driver.
Major maintenance costs are tires and bodywork, and you
have some control over the latter. Totalling the car is
rare, but it happens. Getting hurt is much rarer, but it
happens. You go through two weekends (schools) of
supervised practice and mock races and get to enter
Regional races. Successfully complete these and you get
to enter National races. Once you have the license, you
can show up in a Formula Atlantic (the worst safety flaw
in the whole thing).
Improved Touring: a class where battered, rusty sedans
built between 1968 and about 5 years ago come to trade
paint. Everybody is sure that the guy who just beat him
is cheating, but nobody can afford to post the tear down
bond. loads of fun, actually, but watch out for Volvos
from Hell.
Improved Touring allows for typical (wheels, bars, etc.)
mods. The drawback is you'll work on the car, and not
learn racing nearly as fast. Be like a Formula 1 driver;
just show up and drive. For more info, call SCCA. If
you can't find the number, you don't have the proper
attitude to do this; it takes a _lot_ of perseverance.
American Sedan: Big bore version of Improved Touring;
Five liter Mustangs, Camaros, and Firebirds trade paint.
Modified
Modified Category has five classes, including three intended
primarily for open wheel race cars and two for production
based cars that have been modified beyond Prepared
allowances. In this class, the sky is the limit (almost). In
my region, we have two Datsun Z cars with Chevy V8s and a
heavily turbocharged Miata in Modified, as well as a
fiberglass GT-40 lookalike kit car. Popular Modified cars
include Formula Fords, Formula Vees, and F440s.
The SCCA publishes the Solo I and II Rules in a book that
costs about $10 (for nonmembers, less if you are a member).
The rules are updated annually and the current year's rules
are available beginning in January. The above descriptions
are general and NOT comprehensive: if you are contemplating
modifications to your car for Solo competition, I strongly
recommend that you buy a rulebook. Happy conehunting!
Q:What are the Solo II Classifications for VWs?
A:Here is a list of popular VWs, along with their Solo II
Classifications:
Car Stock Street P Prepared
Rabbit/Jetta, GTI (A1) ES DSP EP
Rab PU/Fox HS DSP EP
8V Golf/Jetta, GTI(A2) ES DSP EP
All 16V ES CSP EP
Corrado G60 DS ASP EP
Corrado SLC (*) CS ASP EP
Passat GL HS DSP EP
Passat VR6/GLX GS DSP EP
Golf/Jetta III, HS N/A N/A
Note: Prepared is currently being massively restructured.
(*): Being considered for a reclassification in GS.
Q:What are the addresses for some of the performance
related clubs?
A:
Sports Car Club of America, SCCA, (General Car Club),
USA, (800) 255 5550
SCCA Cal Club, LA/OC area, Hotline (818) 988-RACE, or
contact:
Lin Jensen (818) 309 95 91
Renee Angel (909) 947 06 44
Ric (310) 496 39 50
Solo (714) 539 22 57
SCCA Cal Club, San Diego, Hotline (619) 441 13 33
Q:What are the some of the performance driving schools?
A:Some testimonials from Ed Priest:
If you can afford it go to a Track Time driving school.
Cost approx $500 for two days of instruction and time on
the racing track of your choice. You learn a lot and it's
a hell of a good time. I've gone twice at Road America
and am going to take the class at Laguna Saca this fall.
The cost is a lot less expensive then Skip Barber and the
rest because you drive your own car - which is what I
wanted anyway. It's really good to find out what your own
car feels like and does at the limit. The good news is
that most of the insurance companies cover you during the
class for no extra charge.
Comment from Mark Sirota:
I've taken both TrackTime and the BMW/Skip Barber
Advanced Driving School. I took TrackTime in 1988 and
Skippy in 1987, so things may have changed -- but I think
the two-day BMW/Skippy street-driving school is probably
the best for anyone who has never done any real racing.
It's currently $975, but worth every penny (and if it
saves you from one accident, it paid itself off). Next
time you buy a car, spend a thousand less on the car and
a thousand more on the driver. And you can take the
gains with you into every car you drive.
TrackTime and similar schools are great fun, and you can
learn things, but not the sort of things that Skippy
teaches. Skippy is much more applicable knowledge, and
just as much fun. Courses taught on real racetracks are
a blast, but are really only relevant if you're gonna be
racing on real racetracks.
Bondurant
Firebird International Raceway Complex
P.O.Box 51980
Phoenix, AZ 85076-1980
(602) 796 1111, (800) 842 72 23
Russel Racing School
Laguna Seca,
1023 Monterey Hwy,
Salinas, CA 93908
(408) 372 72 23, fax (408) 372 0458
Skip Barber Racing School
29 Brook Street
Lakeville, CT 06039
(203) 435 1300, fax (203) 435 1321
For additional Schools, see <A
HREF="http://www.autosite.com/library/drivschl.htm">Drivi
ng Schools</A>
Q:Will performance equipment void my car warrantee?
A:It depends on what and how extensive you modify your car
and whether the parts are street legal. It also depends
on what country/province/state you live in. In the USA,
car warrantees are not automatically voided if you use
street legal (i.e., approved by the applicable
authorities such as the EPA/CARB/NHTSA) components. For
example, changing to Bilstein shocks will not void your
warrantee and neither will changing your muffler to a
Leistritz or Gillette muffler. Things become a bit more
difficult with engine modifications.Your warranty is not
voided unless the dealer can prove that your modification
caused whatever damage your car has. However, it may be
extremely difficult to convince them to do so, and more
than likely they will not want to help you.
CHEMICALS
Q:What is Rain-X? Does it work?
A:It's a chemical to treat your windshield to repell water.
Above certain speeds raindrops will just slide off the
windshield making wipers almost redundant. This product
is used on airplanes. Peoples experiences vary with this
product. It works well on some windshields or types of
glass (most VWs seem ok) not too well on others (for
example, it will have no effect on headlights). In all
situations, it will only last for a couple of thousand
miles. Some have reported that it forms a haze on the
wildshield. I believe that part of the trick to apply
this product right is to start with a very clean
windshield (use alcohol as a final degreaser), at
temperature (18C or 70F) and use extremely clean soft non
greasy cotton cloth.
Q:Can and should I use synthetic motor oils?
A:First have a look at the archive on this. In short,
synthetic motor oils are superior in all respect to
mineral based oils. However, with regular oils being very
good already, the chances of you experiencing engine
failure because of oil viscosity breakdown or other
factors have become extremely rare under normal driving
conditions. Usually, the rest of the cars wears out
first.
However, under higher stress conditions, synthetic oils
will provide you with better protection. Because of
their better flow properties, synthetics are also better
at start up, better in colder climates, and consequently
provide a bit more power (measurable, possibly not
noticable).
If you use a transverse engined car at a track for speed
events (as opposed to a parking lot autocross), you may
actually be in a corner long enough to slosh oil clean
away from the pickup, with possible bad results (please
don't ask how I know: [Editor: I did ask Bob April, and
he managed to push a rod through his engine block. The
failure was traced to inadequate lubrication due to hard
acceleration. He was using Castrol 20W50 in his race
prepped Scirocco]). The real solution is to get a
baffled oil pan, but synthetic oils will do better than
dino oils in this situation.
One of the major concerns with synthetic oils is
compatibility with seals. The newer cars definitely have
seals which are compatible, with older cars this is less
certain. In addition, with older cars using conventional
oils, false seals will have formed (i.e., gunk) thereby
also drying out those seals. Synthetics often have
superior detergent qualities and will often wash away
those false seals causing leaks through the dried up
seals...Sometimes the old seals will recover (because
they are exposed to oil again), but sometimes they won't
hard. So, it's hard to blame synthetics for causing
leaks, it's really the conventional oil that caused the
harm.
The general recommendation with oil change intervals is
to remain with the car's recommendations. With current
VWs this is every 7500 miles or 12 000 km.
The extra cost of synthetic oils is negligable when
compared to other vehicle operating costs including fuel,
insurance, maintenance, and depreciation. Mobil claims
that the superior engine protection, and reduced strain
on batteries and starters, synthetic oils will easily
pay for itself over the life of the car.
Some additional interesting sites to visit are:
<A HREF="vw/FAQs/faq.oil">faq.oil</A> All you wanted to
know about oil/synthetics
<A HREF="http://www.mobil.com/"> Mobil Oil Corp:</A>
Synthetic Oil, FAQs, interesting.
<A
HREF="http://www.xmission.com/~gastown/amsoil/index.html"
> Amsoil:</A> Synthetic Oil Products
Q:Is synthetic oil compatible with other oils.
A:Here is a blurb from Mobil, and it is probably true for
most other synthetic oil.
Compatibility With Other Oils
Mobil 1 is fully compatible with conventional oils. The
two types can be mixed with no adverse effects. Mixing,
however, will reduce the level of benefits Mobil 1
offers.
Precautions for Mixing with other Sythetic Oils
Mobil 1 should not be mixed with any other synthetic
products or oil concentrates. The chemistries could be
incompatible which can lead to a dangerous reduction in
lubricant performance. When switching from other
synthetics to Mobil 1, it is recommmended to flush the
engine first with a conventional oil prior to the change.
REFERENCE MATERIAL
Q:What are some of the Performance books to Read?
A:A nice contribution by Bob April [Edited]:
The following books have been worthwhile to me. In general,
they are like a college education; after you have read them
you will be better positioned to make specific decisions.
"Volkswagen Water-Cooled, Front-Drive Performance Book" Greg
Raven, Available from US mailorder houses. Probably the most
relevant book for Water Cooled VWs. Note that Greg is on the
net at greg.ihr@kaiwan.com
"How to Make Your Car Handle", Fred Puhn. Explains the
basics of car dynamics, why you would want to make certain
modifications, and how to do some of them. [Ed: This book is
pretty old by now and except for the "theoretical" issues,
which are very good, may be a bit outdated. There is however
another book available by the same name but different author
that is more up to date. I have seen copies at better
bookstores and Auto parts "supermarkets"].
"Performance Handling, How to Make Your Car Handle,
Techniques for the 1990s", Don Alexander, Motor Books
International, Osceola, Wisconsion, 1991, ISBN # 0-87938-418-
2. This book seems to be a modern day version of the Fred
Puhn's book though it lacks some of the "do-it-yourself"
procedures (e.g., how to adjust toe, how to make the tool).
"Prepare to Win", "Tune to Win", Carroll Smith. After
reading "Prepare to Win" you will know how to modify your
chassis safely, i.e. why banging bolts in place with a
hammer is bad, and what to do instead. You will also learn
to recognize quality performance parts as compared to cheap
junk. "Tune to Win" is the postgraduate follow up to the
Puhn book. I never would have considered accelerating a
rear wheel drive car to get out of an oversteer situation.
Learn why a Formula V race car has a rear roll bar where
your car has an _anti_roll bar.
"Racing Engine Preparation", Waddell Wilson and Steve Smith.
Old, and discusses V-8s, but there's a lot of stuff you can
use. Waddell's engines have been around Daytona many
thousands of times.
"Bosch Fuel Injection & Engine Management", Charles Probst.
Incredibly clear descriptions of the systems, way too
conservative in describing and valuing modifications.
"Brake Handbook", Fred Puhn. If you're going to do more
than change fluid and pads.
"Clutch and Flywheel Handbook", Tom Monroe. In conjunction
with the shop manual, explained why it was a really bad idea
to speed shift my X1/9 at autocrosses.
"Secrets of Autocrossing", Watts.
"The Front-Wheel Drive High-Performance Advantage", by Jack
Doo, ISBN # 0-87938-298-8, Motorbooks International,
Osceola, Wisconsion
Q:Whar are some of the Monthly/Quaterly Publications?
European Car (formerly VW Porsche): Argus Publishers Corp,
P.O. Box 452, Mt. Morris, IL 61054-0452 800-877-5602. Most
relevant mag in US, [W-VWs & other European cars] Addressed
from here on as [EC].
EuroSport Car, McMullen Publishing, 774 S. Placentia Ave,
Placentia, CA 92670, (714) 572 22 55, fax (714) 572 1864.
New magazine. First issue published in fall 93, published
quarterly. A direct, though less refined (busty babes),
competitor of [EC]. Many articles are almost direct
duplicates of what appeared in [EC]. Addressed from here on
as [ESC].
ENGINE
Q:How can I get more power out my VW?
A:Buy a VW with a VR6 engine :->. It's an FAQ that's worthy
of a book, and that's probably where you should start.
After you go through this FAQ to give you some general
idea, look at the info archive under power upgrades:
http://www.cis.ohio-
state.edu/hypertext/faq/usenet/autos/vw/performance-
faq/faq.html
The actual archives are mirrored at a variety of
locations also mentioned in that FAQ.
Following are a couple of old known modification which are
easy & relatively inexpensive that will increase the power
of the car. In general, the older the car the more room for
improvement. Newer VWs have much less room for easy
improvements because many of the components are already
near optimal.
One easy upgrade path for older VWs is therefore to look at
newer VW (Audi) models, see what they did, and see if you
can swap parts. For example, older VWs have the restrictive
exhaust systems, swapping it with a large diameter one from
a newer model (if possible) or using the catalytic converter
from an SLC will help.
Also be aware when buying "performance" components on their
true benefit. Usually the top horse power gain is quoted
while ignoring the rest of the power band. Your car may
have more top end (high RPMs) while sacrificing power at the
low end (low rpms) which is where most street driving
occurs. The over all effect may therefore be that the car
may actually feel slower off the line, but be great when
passing another car.
So first decide where you want to improve, then research
whether the component in question really achieves that. Also
select performance parts that fit in the stock position over
those that do not. This is probably more true for suspension
components than engine components, but is a good general
rule to follow. Parts that deviate too much may require
extensive modifications, sacrifice reliability, make more
noise, or may even render you car unsafe.
In general: Reduce the exhaust backpressure (performance
exhaust) Advance the timing (recurved distributors,
chips...) Improve breathability (K&N Filter, head port,
throttle body, compressor) Add a hotter cam Enlarge the
engine (change head, pistons, crank) Replace the engine with
a more powerful one.
All cars: Use a K&N Filtercharger air filter element (some
will argue whether this makes any difference). High end
improves a bit. Corrados: 3 HP gain at top. Replacing the
airbox with a filter at the end of the air intake also
provides some additional gain (but you'll also hear more
engine noise...).
Use synthetic oils (motor and transmission).
83-84 GTI:
Change throttle body with a bigger one (Audi?).
[From Peter Tong]: You can get one from a later Audi 5000
of the aerodynamic body style. I think 82 and up.
Another good donor car is the '85 Golf or a Golf that had
CIS-lambda. You have to seal/cap off a vacuum line
coming off it, and in almost all cases transfer your
throttle linkage from your '84 TB to the new TB. Just
make sure that the newer throttle body has a screw
adjustment for the idle speed. You also want to purchase
a really small l screw driver/flat bladed screwdriver bit
to adjust the idle. On the 84s the idle adjustment was a
hex that was easily adjusted on the newer TBs its a screw
and with the TB mounted on your current manifold its
harder to adjust the idle. You also want to make a plate
to put between the new TB and your old manifold to smooth
airflow (your 84 manifold has a TB opening that doesn't
match the newer larger TB). Buy an old style TB gasket,
and a newer style gasket, perhaps new 6mm allen bucket
bolts to attach it, and make the plate to go between it.
If you want a plate cheap just send me $5 and I'll send
you my old one (I had my intake manifold ported and the
opening opened up).
BTW, even with a Fox manifold the TB is good for at most
4hp.
84-87 Scirocco (US):
For the JH 1.8 big-valve engine, use a dual-outlet
exhaust manifold from any early car up to '81, get the
short TT's downpipe (retain cat) for 10 HP, with a 17%
gain at 4200 rpm and more torque Optionally: replace
exhaust system from the cat back (US$150) & factory VW g-
grind camshaft (Autotech, $99)
[From Peter Tong]: What is the difference between the TT
downpipe and the downpipe that come stock with the dual
outlet manifold on earlier cars?
The length is different. The diameter is smaller. The
bends are slightly more abrupt in most cases (some
aftermarket replacement downpipes aren't mandrel bent
even with inner side radius' slightly pinched in). On
most of the earlier cars with cats the stock downpipes
mated before the cat with a flexpipe. The flexpipe
doesn't hurt flow much but is of smaller diameter. Also
the position of the collector on the stock pipe is such
that it would help at higher rpm - the problem is the dp
diameter is too small to support the flow at that rpm
(this is from my experience). In the end count on the
stock dp getting really restrictive around 115hp. When I
first put my 2.0 in and was really revving it - the back
pressure from the stock dp combo was so much that I blew
a nickel sized hole it it! This happened even though I
was running a 2" exhaust and supertrapp rear of the cat.
Kind of funny but it happened to seak out the weakest pt
on my stock dp and took it out. The stock dps also
have two welding methods that I've seen holding the
exhaust manifold flange mating surface. One uses a small
metal "brace" the other type is just welded to the pipe.
The TT downpipe is nicely made and has worked well on my
car. It is stiff in many ways compared with the stock
system, and tends to transmit more vibrations than the
stock system (perhaps due to the stiffness). The
collector joins about 2.5-3" before the cat and is 2"
diameter pipe. Tubing is mandrel bent and the angles
aren't quite as severe as on the stock dp. Also you
eliminate the flexpipe with the TT cat dp. What did it
do? When I installed it - the midrange really improved.
Top end also to a lesser degree.
As for actual #s for what they did on my car:
40-60 in 3rd gear: 4.6s before and 4.3 after. This
tests 3k to 4.5k rpm.
50-70 in 4th gear: 7.9s before and 7.5 after. 3rd
is 1.29 and 4th is .91.
r&p is 3.89.
So you can see it improved the midrange by about a 6%
average. Is it worth $115? It is I guess - it depends on
if you are a geek like I am at trying to extract as much
out of your engine as possible. As it is that pipe, the
G-grind and the TT adjust cam sprocket are the only
aftermarket items that were necessary for me to purchase.
Oh BTW, fuel economy should improve slightly as well.
Fox:
Remove exhaust restrictor (see also further and EuroCar:
April 89, Aug. 89, Dec. 89, Apr. 90, Aug. 90)
90-92 Passat (4 Cyl):
Remove air-intake restrictor, APS Chip, cam. APS chip for
automatics that is supposed to do wonders for low end and
shift points. Applicable to all cars with 9A engine (inc.
16V GLI).
85-92 8VGolfs/Jettas:
The biggest gain can be had with a better down pipe and
exhaust system.
85 GTI:
Change ignition map by cutting wire #11?? on the ignition
control unit and grounding #3 (which was connected to
#11). Yields 2 HP additional, torque peak occurring at a
lower rpm. See also 85-87 GTI for additional power.
85-87 GTI: KE-Jetronics:
Advance ignition idle timing to 12 degrees BTDC or until
knock. (factory specifies 6 degrees +/- 2). Gains 5-8 HP
with >= 92 octane fuel, very noticeable at the low end.
Note, it may reduce the life of your catalytic converter.
90-92 16V GTI/GLI:
Motronic Power chips from Autothority & APS.
Corrado G60:
Stage 1, 2 & 3 chips/packages from APS & Autothority (&
others).
Stage 1/P-Chip: Chip swap, improves low end by torque
18%, high end by ~5%. Gas consumption
improves but you do need Super Unleaded. One of
the BEST improvements you can make to this car.
Stage 2: Pulley change, chip & fuel pressur regulator
(AT) or exhaust (APS) => Power boosted to 180 (APS)
or 200 (AT).
Noisy, too powerful for the car, APS is more
drivable,
AT's not CARB approved. Gas consumption near stock.
Stage 3: Like Stage 2 but with a cam, affects mostly high
end.
Remove cold air snorkel (too restrictive) => 1-2 HP gain
at the top end (Note: WAY too noisy).
Use Neuspeeds Generation 2 system. It solves the airleak
created by the idle stabilizer valve. This mod
seems to work with most of the above mods as well
and provides better boost under all conditions.
See also archive G60_Power_Upgrades and Air_Intake_Mods.
VR6 2.8l & 2.9l Models (Corrado SLC/VR6, Passat GLX, Golf
III, Jetta/Vento):
Power chips available from both APS & AutoThority &
others.
Stage I/P-chip: Gain of 7-10 HP at the top end. Most
people reported little or no gain. Some have
complained that AT's chip seems to produce knock.
Replace throttle body w/o internal air ramp (10% more
airflow). This is nothing more than the European
progressive TBody. It does make the low end a tad
weaker, which, combined with other enhancements
will make the car less jumpy.
K&N P-Flow filter. APS recommends the above 3 combined to
produce the best effect to produce an additional
30 HP.
Remove cold air snorkels (too restrictive). Their
technical name is "Helmholtz resonator", and it's
indeed a sort of muffler.
Get a new set of cams, such as those from Schrick. Note:
Mostly improves the top end.
Use VW Motorsport's Variable Inlet Manifold (VSR). See
archive on this. An alleged gain of 30-50 HP at
3000 rpm! Expensive (2300US$), but chances are that
certain shops may produce a low cost immitation.
Buy a turbo charger kit. VW is about to release a Van
called the Sharan that uses a 250Bhp Turbo VR6.
Other turbos on the Vr6 have produced around 300Bhp
making the car virtually unmanagable.
There are a few 3.1 liter conversions available. Not
enough info on that as yet.
>>>Probably LOTS MORE...
Caveat: Most of the above are merely small fixes that do not
require replacement of a major engine component such as the
cam or the exhaust system, which is usually the next step
towards major engine improvements. Those enhancements
require a lot more work and expertise to install.
Caveat II: Most of the above improvements are approved by
the air resource boards for street legal use, but some are
not (Stage II, Corrado). Before you install any equipment,
make sure that you understand the full implications.
Tampering with pollution control equipment is a serious
crime, punishable with a 20 000 US$ fine in many states of
the USA.
Q:What's a K&N air filter?
A:It's a washable (i.e., reusable) air filter made out of
an oiled cloth like material over a wire mesh matrix. It
is supposed to let through more air while retaining the
same filtering capabilities. More air => more power,
especially at higher rpms.
In practice however, the reviews have been mixed. Hot VWs
(Dec 92) reported a 3-5 HP gain on the high end in a
Jetta. Others have reported no difference or even a
slight degrade in performance. My *speculation* is that
some cars require to see some vacuum to get the right
amount of fuel, kind-a like a choke (e.g., carbureted
cars). The same is true with some FI cars (measure
vacuum) while other FI cars measure air flow. By the way,
a 3-5 HP difference is within normal daily variance of an
engine because of external factors such as gas quality,
viscosity of the oil, ambient temp, etc. You can probably
gain as much from pumping up your tires harder to reduce
rolling resistance (but increase wear).
From Mark Sirota: I put a used K&N on a flowbench against
a couple of other filters, including both types of Bosch
filters. The used K&N flowed FAR better than anything
else I tried -- by a very significant difference. So the
K&N filter alone is definitely an improvement, *if* the
air filter is the most restrictive element in the system.
I have no idea if that's true.
Q:How do I service a K&N air filter?
A:You can buy the K&N chemicals (cleaner and reoiler) or
you can use a detergent called Formula 409 (used for
cleaning kitchens in the US) to save some money (the K&N
cleaner is rumored to be the same as Formula 409). You
should always use their oil though. Also do not rinse the
filter in hot water. It'll shrink the cloth.
Q:How do I keep my engine cool?
A:Keeping your engine sufficiently cool is needed for all
the obvious reasons. VW engines like to run hot, and are
more efficient that way. However, under high stress or
race conditions, the factory system may not be
sufficient. If you run too hot your power is reduced due
to engine knock.
There are several ways to aleviate this problem: 1)
Increase heat transfer with a different cooling fluid or
wetting agent. 2) Increase the cooling capicity of your
car with a larger radiator.
The reason why I do not mention changing the thermostat
to a lower temp one is because it merely reduces the
average operating temp (which may be too high), but does
not change cooling capacity. In extreme conditions the
temp rating on the thermostat is not going to matter
because they will all be fully open. It is however a good
idea to make sure that your thermostat still is capable
of opening fully at the intended temp.
Q:How can I improve heat transfer/what are alternative
coolant fluids?
A:Redline sells a "wetting" agent calleed "Water Wetter" as
an additive that improves heat transfer. It comes in two
forms solid (discontinued), which contains phosphates,
and liquid w/o phosphates (OK). People who have used it
can't tell any difference under normal driving
conditions, but it does make a difference if the problem
is that hot spots in the cooling system are causing
localized boiling
Under normal street use you will not see any change
because the thermostat is regulating the temp. It's only
when you exceed the capacity of your system and the
thermostat is all the way open that the wetting agent
will have an effect. The wetting agent is supposed to
improve heat transfer by reducing surface tension. This
is important near the head where the coolant my locally
boil. The little gas bubbles however impede heat
transfer, which in turn may lead to knocking and reduced
engine performance. Redline claims it can reduce engine
temp by as much as 30F (depending on the anti-
freeze/water ratio, for a 50% mix it's closer to 10F I
think). The performance shop I bought it from said that
its good insurance when your car is put under heavy duty
(stuck in traffic on a hot day, making a desert run,
autocross).
Another issue is that glycol raises the boiling point,
but reduces heat capacity. With Water Wetter, you can
hopefully use less glycol, resulting in higher heat
capacity. You want to use as little glycol as you can
while still avoiding boiling (and still getting enough
lubrication for the water pump, which glycol provides).
Note: In certain old high mileage cars, the Water Wetter
scavenges out some of the contamination in the cooling
passages and holds them in suspension in a way that
resembles motor oil. The stuff even "feels" like oil.
Redline said this was quite harmless otherwise, and I
shouldn't have any problems with hoses or the like. They
said because it only happens in a few cars, they didn't
feel justified in putting out a warning notice
(especially if it causes owners of cars with REAL
problems to ignore it).
An other alternative described in European Car (Oct 91)
is to use !pure! propylene glycol that has a higher
boiling point than ethylene glycol though worse heat
transfer properties. [borowski@hpspkla.spk.HP.com] The
higher power VW engines have a problem with pinging under
heavy load. This is due to the coolant boiling inside the
head. Coolant vapor is a very poor heat conductor. This
loss of cooling causes hot spots to form on the
combustion chamber side of the head, causing pinging. The
propylene glycol does not boil, and this cools the hot
spots better. Thus, pinging is avoided, and more power is
available if the timing is set to take advantage of the
reduced chance for pinging. The cooling system is NOT
pressurized, but vented to boil residual moisture away
(which lowers the boiling pt). A kit to make the switch
is available from: MECA Cooling Company [See the first
general FAQ for address]
Q:Do "Split Fire" (= name of a plug sold in the US, not a
type of plug) plugs live up to their advertised claims?
A:Responses from the net & tests by TT indicate: NO, they
are actually worse than the recommended Bosch plugs. Note
that VW recommends the use of tri- cathode Bosch plugs
for some of their cars...so this split-fire idea is
rather "old". Apparently it's covered with Techtonics
"Amazing Dyno Stories: Parts to get and parts to forget".
There's an article in the August 1994 issue of EC where
they talk about ignition systems and specialty spark
plugs. They interviewed Dr. Chris Jacobs of Jacobs
Electronics. The gist of the article is that, cars with
weak ignition systems get the most benifit form these
special spark plugs (SplitFire, V-groove, etc.) However,
the same cars perform better with stock plugs and an
improved ignition system than with the specialty plugs
and the stock system. [Ed's Note] Most newer VWs have a
pretty efficient ignition system, and may see little or
no benefit from such plugs or an enhanced ignition system
by Jacobs.
Q:What net wisdom exists on exhaust systems?
A:Gilette: Good balance for street and autocross & last
LONG. Some will debate that this is the best (stainless).
OEM supplier to VW. Leistritz: Good balance for street
and autocross. Galvanized. Note: Stock on VR6 Corrado &
Passats.
Supertrapps: GREAT for road racing and autocrossing but
way too loud for everyday life (rgolen@UMASSD.EDU)
OEM: More recent VW mufflers have improved to the point
that little can be done to improve them in street legal
performance or durability. Also keep in mind that VW now
offers lifetime warrantee on their replacement mufflers.
Remus makes some interesting exhausts with dual cat-
converters. Expensive though. Remus mufflers are
easthetically pleasing and almost too nice to use as
mufflers. Remus is much better known in Europe than the
USA.
Borla: Insufficient data. I believe New Dimensions is
using their final muffler.
Some of the performance shops now also make their own
exhaust systems [e.g., EuroSport, Techtonics, AutoTech,
Velocity Tuning] with galvanized or steel tubing and 3rd
party mufflers such as DynoMax. The quality of these
systems vary, and it's therefore hard to make a sweeping
generalization. Some work well, others don't. Check
around before you buy.
Unless you drive a beater and don't really care, avoid
Midas. Their mufflers are cheap, reduce power, don't
always fit right and they only offer a life time
warrantee on the mufflers and not on the tubes (which are
expensive, and the first to go).
See also the Exhausts archives on this!
Q:Removing the restrictor in a VW Fox to get more power?
A:There is a steel doughnut going right before the cat.
This stock doughnut has a two inch (approx) hole in the
center for the exhaust to flow thru. It can be replaced
with a doughnut with a 2 1/2" (approx) hole to make the
exhaust breathe a bit easier. Not a significant power
increase, mind you. [mgm@royko.Chicago.COM (Marty
Masters)]
Q:What is the relationship between torque and horsepower?
A:
RPM * torque(ft-lb)
HP= ----------------------
5252
Anyone have the metric version? I am too lazy (i.e., kW =
Nm * RPM / 60?)
Q:Should I remove the catalytic converter?
A:Not if you want to remain street legal, and unlike in the
early 70's, these devices have improved so much that the
loss because of it has become minimal or in some cases
removing the cat will rob you of power. Note: The
Catalytic converter on the SLC is rumored to be one of
the most free flowing of any VW, and will provide gains
when used on a Passat (or possibly other cars). New
Dimensions is toying around with this.
Note: In the US there is 20 000 US$ fine for messing
around with emmissions control equipment. Of course the
chance of being caught is rather minimal.
Q:Are the performance chips interchangeable between cars
with similar engines, e.g., VR6 Corrado and Passat?
A:NO, Almost all the chips are different, even within one
model. For example, the 92-early 93 US Corrado VR6s have
compatible CPUs and chips, but are not compatible with
later (distributerless) VR6 Corrados. The chips are
ordered by the box number on the CPU and are not
interchangable.
Q:Which performance chips are recommended for VWs?
A:See the archives on Performance improvements as well as
the Wired article. The two most trusted companies for VWs
chip makers are Neuspeed and AutoThority. There are some
disputes that one is better than the other, but it's
mostly a matter of compromises. In regards to SuperChips,
their reputation has been tainted by some questionable
claims and 300$ improvements that had nothing to do with
reprogramming the chip (you get back the stock chip!).
AMS is also trying to enter this market, but so far there
is insufficient data on this.
ELECTRICAL
Q:How can I improve night visibility/increase light output?
A:It all depends what you are starting from, and in what
country you live. USA: Sealed beam units till 84
required, "aerodynamic" allowed thereafter but must still
conform to a rather pointed spread. 3 DOT nipples for
alignment required. Canada: Same as USA. Northern Canada
has slightly different regulations. Europe: Sealed beams
forbidden. Light is more evenly distributed. Some
countries require yellow lights, and different settings
for city, highway and hi-beam lights.
Beware that whatever you do, you must NOT blind on coming
traffic. Some of the suggestions below are actually
illegal for street use in the US. However, judging from
the large number of misaligned lights in the US, your
"illegal" mods will be less blinding than a normal but
badly aligned set of lights. However, oncoming traffic
may automatically assume that you are blinding when they
see more than 2 lights on at once (+ it may be illegal in
some states/driving conditions). EuroCar had several
articles on lighting in 91/92.
To improve visibility, try the following:
- Align your headlights. See Bentley or your local code
for specs. I usually go a tad higher than the specs w/o
blinding.
- Change to halogen lights (yes, some of the sealed beam
units are not even halogen).
- Clean the inside of your non-sealed beam units with
some alcohol on some cotton/rag at the end of a
wire/stick. (Pretty tricky.)
- Add fog lights (very wide, low, but not far reaching).
Set up correctly, fog lights DO NOT blind, per
definition. Don't buy generic brands, but minimally go
for Bosch, Hella, Cibie and others.
- Add driving lights (narrow and far reaching). Set up
according to specs these DO blind, however, they can
often be set up lower so that blinding can be almost
entirely eliminated. - Change to one of the non-sealed
aftermarket units, which are usually the European style
lamps.
- Change to the equivalent European "aero-style" units
(e.g., A2 Jetta). These are available from a number of
sources and have much better beam characteristics than
DOT approved lamps provide. Your ability to use them
will be a function of the level of detail your state
motor vehicle inspection requires. In NJ, they have to
come out to pass inspection [Tom Coradeschi].
- Change to poly ellipsoidal, high-energy, "DE" lights.
This is the newest technology in lighting technology,
more commonly found on newer BMWs (though BMW uses an
arc lamp rather than halogen). EuroCar had several
articles about these in 91/92.
- Change the wattage of your bulbs. This is actually not
always a good solution because your lenses may crack
because of heat build-up, moisture accumulates faster,
wiring may not be able to carry the load, may blind, may
not fit in all non-sealed units [According to Andy, you
cannot not put higher wattage lightbulbs into the stock
North American light lenses.
[Unverified...jan] The 70/90 Watt versions of the H4
can be bought at off-road places such as Competition
Limited, (313) 464-1458 according to Dilmore. There are
also 45/100W versions of the standard 45/65W lamps. Some
lamps require you to trim a metal tab that would normally
prevent their use for street cars.
From Michael R. Kim: I've got 80W low beams on H4, and
haven't had any problems being pulled over. I drive with
friends a lot, and ever since installing the lights, I've
asked them about glare, for fear of getting a ticket.
They told me that since I've angled them down just a tad,
they don't notice any more glare than a car with factory
lighting. Mind you, if you've ever seen one of those
Ford F150 trucks, with their lighting, you'd question
about proper light angling. I've had the lights in now
for almost 5 months now, and have yet to even get a flick
of the high beams from someone else for blinding them
with 80 W beams. I would definetly recommend upgrading
lights, it can do wonders for your driving, but PLEASE
double check your alignment and light pattern before
going off to test how well they work.
TRANSMISSION
Q:Should I change to a racing clutch?
A:In most cases a racing clutch ("4 puck") is really not
needed for street or Autocross uses. VW clutches can
easily handle well above stock power. For example, a 16V
210 mm GTi clutch is good to 160 bhp. Furthermore, racing
clutches are very harsh (like, all or nothing) and much
stiffer to depress. One of the more agreeable changes is
to use a stronger pressure plate with a stock clutch
disc.
Q:What transmission fluid should I use (manual cars)? Why
is it important for racing?
A:If you use a transverse engined car at a track for speed
events (as opposed to a parking lot autocross), you may
actually be in a corner long enough to slosh oil clean
away from the pickup, with possible bad results (please
don't ask how I know). The real solution is to get a
baffled oil pan, but synthetic oils will do better than
dino oils in this situation.
As far as I know, most/all water cooled VW transmissions
require gear fluid with an API rating of GL-4 (MIL-2105).
The recommended GEAR viscosity hovers around 80W, 75W-80
or 75W-90 Note that 75W-80 GEAR oil is equivalent to
10W30 MOTOR oil, but it is NOT recommended to use motor
oil in gear boxes, even though some Japanese cars do so
any way (has to do with shear strength). GL-5 oil is made
to lubricate gears (like in a differential) and may cause
premature wear on brass synchros.
NOTE that GL-5 is recommended for the *differential* on
some AUTOMATIC VWs and on some manual transmissions.
However most VW *Manual* transmissions need GL-4. Check
your user manual or VW.
Quality of the gear oil makes a HUGE difference in
shifting. I have personally tried Castrol (HORRIBLE),
SWEPCO (Better), VW gear oil (good, I suspect that they
use a synthetic in some cars), and Redline MTL (best so
far). Others seem happy with Mobil 1, Synthoil, Spectro,
etc. How these oil affect transmission life is unknown to
me. Note that MTL is rated 75W80, while their newer
product MT90 has a rating of 75W90 which may be closer to
the required viscosity of your transmission.
VW also sells synthetic transmission oil (at US$20/liter)
which is probably one of the best oils to get.
Most VW transmissions use somewhere around 2-2.5 liters
of oil. Before you drain, make sure you have something to
catch the oil (an old jumbo coffee can is perfect). Open
the side fill hole first, because you'll have to fill it
up to either the fill hole or BEYOND. You'll therefore
either have a little bit leak out or 1/2 liter gush out.
To drain (the rest), unscrew 17 mm allen plug at the
bottom of transmission. To fill, either unscrew
speedometer cable or use the fill hole on the side. Some
VWs require the level of the oil to be just so that some
drips out of the fill hole, others (some A2 Golfs/Jettas)
require an additional 1/2 liter on top of that. That's
why it's a good idea to catch the old stuff and check the
fill hole first.
[NOTE: Some VW User's Manuals apparently do recommend GL-
5 in some transmissions, so check first! blu@cellar.org
seems to be doing ok with Redline GL-5 after 100kmiles in
his car. However, Peter Tong had bad experiences with
GL5: he could not get out of 3rd gear with GL-5 oil.]
[NOTE: One recent posting by (Paul Keller) blames his
transmission failure on MTL, and claims that Redline
recommends MT90 only for VWs. At this point it is unclear
to me whether MTL is to blame, and whether using MT90
would have made much of a difference. Keep in mind that
he is one of two so far which blame Redline out of many
who have had no problems so far.]
TIP: Glue a small round magnet on the outside of the
drain plug. They can be bought cheaply at electronics
stores, and it will attract metal particles that may
damage the transmission. Older VWs used to have magnetic
drain plugs, but VW stopped using them for some reason.
Some newer VW trannys now have this magnet BUILT in
permanently.
Q:What's the difference between the normal wheel bearing
grease and Spectro SPL grease?
A:The front bearings on VW's tend to take a lot more abuse
than on other makes, so many people recommend that you
use a synthetic like Spectro to help them last longer.
However, there also seems to be some confusion on the
matter: most normal drivers are easily able to get 100K
mi. out of their front bearings. This is in contrast to
racers, who may have to change bearings every race or
two, and to GM products, which are supposed to have new
bearings every 50K mi. (according to a sign on the wall
of a local dealership). [sobiloff@lap.umd.edu (Blake
Sobiloff)]
BRAKES
How to improve/vented/cross drilled/pads
Q:What and why vented rotors?
A:Braking converts motion into heat. Heat needs to be
dissipated. The faster you can dissipate heat the better
you can stop, and less fade. Vented rotors essentially
have two parallel "discs" with an airspace in between to
increase cooling. Many of the Kesley-Hayes non-vented
front rotors can be replaced with vented ones and thinner
pads without replacing calipers for a slight gain in
braking power.
Q:Why cross drilled rotors?
A:Braking produces gasses, and cross drilling give the
gasses a way to escape, thereby increasing contact
pressure. In addition, a cross-drilled rotor now has more
surface area, and thus cools down more quickly.
Personally [Jan] I do not advice cross drilled rotors
because of the increased likelihood of cracking. DO NOT
CROSS DRILL ROTORS YOURSELF. It's usually done on an NC
machine at calculated positions followed by stress
relieving.
The comments from people on driller rotors are that they
improve braking under competitive situations, but only
provide a marginal benefit under normal street use. The
also feel more uneven when you brake (esp. the slotted
ones) and are also noisier (they "humm"). Note that cross
drilling is actually banned for certain competitive
events, so check before you invest. Cross drilled rotors
will also wear out your pads in a big hurry.
Another alternative to x-drilling rotors is to buy
slotted or grooved rotors and pads.
Q:Is it worthwhile changing my rear drums to disc brakes?
A:For normal purposes: NO. For racing and other purposes,
maybe. Considering the high cost of this swap and
considering that only 30% of all braking power comes from
the rear, it is usually not worth the effort. Concentrate
on the fronts instead.
Q:What are the benefits of steel braided brake lines?
A:The reports I have received is that it improves brake
feel marginally (less expansion of the tubes) but that
the steel is also subject to more corrosion.
[According to Volney.Spalding@Corp.Sun.COM]: They are not
recommended for street use. Reason: Lines are rigid and
will not flex with the body as it turns and reacts to
road imperfections--rubber hoses will. As a result, the
lines can often get pinched and fail. Stainless lines are
OK in racing applications because race cars are subject
to constant inspections/bleeding/maintenance. If there is
an alignment problem it will likely be discovered. Most
people probably are not as disciplined in street
applications making the this mod impractical. In
addition, most steel braided brake lines do not pass the
DOT tests and therefore technically illegal for street
use.
Q:What pads should I use?
A:See the discussion in the technical FAQ and also in the
archives. It is important to realize that "race pads"
(e.g., Ferrodo, to some degree, REPCO Metal Masters) only
work well when HOT, and are therefore not well suited for
calm city driving. You WILL slide through your first
intersection in the morning with these pads. Mintex
SilverLine pads are between Repco MMs and stock pads.
They may work fine for some cars, but I personally missed
the initial bite too much in my G60 that I switched back
to stock pads.
Note that the company that makes both Repco and Mintex
pads is currently in the process of reformulating their
compounds.
>>>>VOLUNTEERS>>>>????? Needed: diagnosing problems
TIRES/RIMS/SUSPENSION
Q:I want to improve the handling of my VW? Where should I
start?
A:Start reading back issues of EuroCar & VW Performance
books. It all depends what you want and for what purpose
(street, autocross, etc). In general people follow the
following road to better handling: Tires and rims,
shocks, sway bars,stress bars.
Tires & Rims:
Probably the biggest single improvement you can make is
by changing the stock tires, and in some cases the stock
rims. It all depends how much money you have, and what
you have as stock equipment. If you want to keep your
original rims go to a stickier tire in the stock size.
Next step up is a wider tire with a lower aspect ratio
for the same rim, e.g., 165/80-13 to 175/70-13 (this is
called plus ZERO).
To make a more significant impact, you will have to
change rims (but be aware that it may put you into a
different auto-x category). Generally, you go with larger
rims (in diameter) with lower profile tires (=> less tire
flex => better handling) and also with wider rims (=>
more sidewall rigidity) and wider tires (=> larger
contact patch on dry roads, more hydroplaning on wet).
Most FWD VWs are made to be run with tires around 1816 mm
circumference, so each time you go to another combination
you try to stay within a few percent of this
circumference so that your gear ratios and speedometer
readings remain the same. Odd as it may seem, rims are
still measured in inches eventhough the rest of the car
is metric...
The upgrade gategories are called PLUS ONE, PLUS TWO,
PLUS THREE, and so on, with each "+" referring to an
additional inch in rim diameter starting from a 13" rim
as a base. Note therefore that many of the VWs you buy
nowadays are already at +1 or +2.
Here's M. Sirota's extensive list of NOMINAL sizes.
Actual sizes vary (note the c-program to generate these
are in the archives):
Spec. Side Radius Diam. Circumf.Revs/Mile Difference
wall
BASE:
155/80-13 124mm 289mm 578mm 1816mm 886 0.0%
165/80-13 132mm 297mm 594mm 1867mm 862 2.8%
PLUS ZERO:
175/70-13 122mm 288mm 575mm 1807mm 891 -0.5%
PLUS ONE:
185/60-14 111mm 289mm 578mm 1815mm 887 -0.1%
195/60-14 117mm 295mm 590mm 1852mm 869 2.0%
205/55-14 113mm 291mm 581mm 1826mm 882 0.5%
PLUS TWO:
195/50-15 98mm 288mm 576mm 1810mm 889 -0.4%
205/50-15 102mm 293mm 586mm 1841mm 874 1.3%
PLUS TWO (MUD AND SNOW):
185/55-15 102mm 292mm 584mm 1836mm 876 1.1%
PLUS THREE:
225/40-16 90mm 293mm 586mm 1842mm 874 0.0%
Going from 165/80-13 to 205/50-15 will make an enormous
difference, however going from 195/50-15 to 205/50-15
will provide less of an improvement (see other FAQ).
There are also additional factors to take into account.
The first is that tires can only be fitted on rims with
certain rim width limts and secondly, there is a limit on
how wide a rim AND tire will fit on your car to avoid
rubbing with the struts/shocks and fenders. The last is
that you also need to get a rim with the correct offset.
These are all explained further below: Also keep in mind
that for certain competitive events, changing to
different size rims may put you in a different class.
TIP: [From Roy Kao] DON'T SKIMP OUT ON CHEAPER TIRES!! An
investment
in good mags is useless with cheap tires.
Q:What are the rim width ranges per tire size?
A:The rim ranges per tire width (from a Euro-Tire's
Catalog) are:
TIRE RIM RANGE Diameter
185/55-15 5"-7" 23.03"
195/55-15 5.5-7 23.43
195/50-15 5.5-7 22.72
205/50-15 5.5-7.5 23.11
Q:What is the largest rim/tire sizes that will fit on my
VW?
A:It depends from model to model. Also, make sure you get
the right rim offset or your handling may degrade.
Scirocco I:
Front: 185 or 195 mm wide depending on model Rear: 205
mm (?) Max Rim: 15"x6"
Scirocco II: 205?
Rabbit I:
205/60R13 will fit fine.
Rabbits/Jetta: Usually > Scirocco!
GTI I:
15x7.5 will probably work, depending on what tire
you choose.
Golf/Jetta II:
215/45R15 fits, at least on a GTI with flared fenders.
15 x 6 & 195/50/15 fit also, =? GTI/GLI GTI/GLI: 215?
Corrado:
Lower rim limit are 15" rims due to brake calipers,
16x7.5" rims with 205/45/ZR16 work fine.
Tire limit =? 225
EuroTire sells 15" steel rims for mounting snow tires.
17" rims may rub and require to roll the fenders
Passat: ?
A3 Golf (EC March 1994):
7x15, 195/50 or 205/50, 35mm or better, 38 mm
offset.
16" rims: 16x7.5 with 205/45-16 or 215/40 R16. 225
are TOO large.
17" rims: too easy to bend a wheel
Remember, offset is very important in determining tire
fit!
>>>ADD MORE ENTRIES>>>This needs to be improved [jan]
Q:What is rim offset? [D="EinpressTiefe" or "ET" Value]
A:The distance between the rim's center line and its
mounting surface. From the picture below it should be
obvious why it's important to retain proper offset when
you change rims: tire not centered properly affecting
drivability (negative roll radius changes), bearing load,
rubbing on the struts or wheel arches, etc.
Cross sectional view of a rim:
Center Plane
|\____+____/|
|_____.____ | Street Side of Rim
. //
. //
. || Mounting Face
. ||
>--< Rim Offset
NOTE: Apparently a deviation of a 5-8 mm does not seem to
be too critical according to [Nick Cremelie].
Q:What are the "standard" VW wheel offsets (the amount the
rim is offset from the hub)?
A:Rim Offset [From TomH, unverified but probably correct]
13x5 45 mm
13x5.5 38 mm
14x6 38 mm (A1 & A2 cars)
14x6 45 mm (A3 cars) NOTE THIS IS UNVERIFIED
15x6 35 mm (BBS 1-piece, # 165 601 026 091)
15x6.5 33 mm (BBS 2-piece)
Q:What is the proper tire inflation for my car for
performance driving?
A:For performance driving things are a bit differently from
normal inflation pressures because there the aim is to
reduce tire flex and to adjust the over all handling
characteristics of the car. Generally, in an autocross or
a ralley you will be running at a much higher pressure
than normal. One of the old tests is to put chalk marks
on the side of the tires, go around the track, and check
how much the tire has "rolled" under (i.e., how much flex
caused you to scuff the sides of the tires).Note -- this
only works on "street" tires. The sidewalls on
competition tires are just too stiff for the chalk
technique to work -- you need to use a pyrometer and a
stopwatch.
where@maple.circa.ufl.edu on chalk:
Typically speaking, If you run street tires when you
autoX, you'll want to bump the pressures up from what you
run on the street, but ONLY for the time you're racing.
When your racing day is done, bleed the pressures back
down to reasonable street pressures, and drive home.
Many of the autoXers I've talked with run "race tires"
while they race. They bring them in the trunk and take
them home in the trunk, and only run them around the
track. WHY? because these guys run racing slicks, and
everyone knows that racing slicks will KILL you if you
run them on the street and it decides to rain. If that is
not enough, you can be written a citation by the police
for running "bald
tires" if you are caught running slicks on the road...
Ok, now if you're still not sure how much pressure to run
in your street tires, ask someone who has a nice
(professional looking) AutoX car out at the track.
There's some sort of formula relating to a set of chalk
marks that you make on your tires. You "chalk the tires,
make a run, and analyze the chalk marks". If you find
someone who has raced several times, they'll usually be
nice enough to explain it to you, and help you out.
Contrary to what some may think, If you are just starting
out autoXing, the veterans are actually VERY willing to
help you out and explain things like tire pressures and
driving techniques. Most of them would talk your head off
if you wanted to listen that long, they're a really
friendly bunch from what i've found. The rationale for
explaining things to novices is to shorten the time that
it takes to get the car tweaked, so that you can spend
more time behind the wheel perfecting your driving
technique. Afterall, it's driving technique that really
makes the difference, They'll tell you that. :)
fisk@cvdv99.mayo.edu (Tom Fisk | 751 Siebens | 6-4261):
OK...there are several ways to determine proper tire
pressures for autocross. The scientific way says that you
run a few circuits and then check your tire temperatures.
The temperatures should be even from the outside, middle,
and inside of the tires. If the tire is warmer in the
middle, then your tires are OVER-inflated. Warmer on the
edges means that they are UNDER-inflated. If you get
variation from one side to the other, than that means you
could adjust your camber (+ camber if the inside is
warmer than the outside) and visa-versa.
For novice drivers in FWD cars on street tires, I would
recommend starting at 40-45psi in the front and 30 in the
rear. With experience, this will change. Novices need a
little more up front than experienced drivers, because
they always turn the wheel too far and never unwind
properly on the way out of a corner.
Q:What are examples of proper tire inflation autoX?
A:Examples of pressures used:
[Jeffrey M. Mayzurk] On my DSP Scirocco (2300 lb, 55/45
distribution), I usually run with the fronts at around 38
and the rears at 30. This is plenty of pressure to keep
the tires from rolling over, and I like theway it
handles.
jstulen@eis.dofasco.ca (James Stulen):
I run an 84 Rabbit GTI (ok, it's not quite an SLC) with
some mods, on 185/60/14 RE71S tires. I use 36-38 in the
front, some time as high as 40 if they're scrubbing to
much. I use 26-30 in the back, any more and they just
don't 'work', very tail happy then.
On the '87 GTI 16V with 218 or 206-compound BFG Comp T/A
R1's, I ran 36 in front and 22 in back. Note that these
tires require MUCH lower pressure than street tires.
Q:How can adjust over/under-steer behavior of my car?
A:From Jeffrey M. Mayzurk and also the APS catalog:
More Understeer More Oversteer
(less oversteer) (less understeer)
decrease front tire pressure increase front tire
pressure
raise rear tire pressure lower rear tire pressure
increase front swaybar diameter increase rear swaybar
diameter
decrease rear swaybar diameter decrease front swaybar
diameter
less front camber more front camber
increase rear camber decrease rear camber
increase front shock stiffness increase rear shock
stiffness
decrease rear shock stiffness decrease front shock
stiffness
(Note: 'camber' above refers to NEGATIVE camber.)
BIG NOTE: The above refers to conventional wisdom.
HOWEVER, A1 & A2 VWs benefit tremendously from a thicker
front sway bar to reduce understeer due to camber
changes. See the section on sway bars!
Q:My VW lifts its rear inner wheel in sharp turns. Is this
normal?
A:Yes, all VWs do this. [From drbob27@aol.com (Drbob27)]
The reason VWs do this is that VW minimizes front wheel
drive understeer by making the rear roll stiffness much
greater than the front. When the car rolls, the back is
so resistant it picks up the inside rear. The sway bars
(actually the ratio of front/rear roll stiffness from
bars and springs) CAUSES the wheel to lift. Porsche 911s
used to lift the inside front for the same reason
(reversed). It's one of the reasons people hold VWs in
high esteem as responsive, while similar cars are cited
for understeer. I used to race a Scirocco Showroom Stock.
In a corner, the mark of a truly excellent turn was to
pick up the inside rear smoothly to 4-6 inches and hold
it there steadily through the turn. Less competence
showed if the wheel bobbed up and down.
Q:Are VW rims interchangeable?
A:Most VW rims are interchangeable, and it may provide for
an inexpensive upgrade from you stock steel rims to used
stock alloy rims of an other VW. The exception are the
Corrado G60 and the SLC which both require a rim with
minimum 15" diameter; the Jetta GLI/GTX 16V (and I think
Passat) require a minimum 14" rim, while all other VWs
will take 13" rims.
VW uses five distinct bolt patterns:
5/180mm (?) Early air-cooled
4/130mmLate air-cooled
5/130mm (?) Transporter/Vanagon
4/100mmWater-cooled
4/100mmWater-cooled
5/100mmVR6 models
The standard rims will also work on any car with a 4-bolt
100mm hub. These include Honda (some models), BMW (3-
series, 2002...), Omni GLH, Mazda (Miata and possibly
others), and any Audi 4-bolts before they switched to
108mm.
NOTE: Check OFFSET and center opening before attempting
swaps! VW hubs *MUST*BE*HUB-CENTRIC*. This means that the
hub opening of the wheel must fit the wheel hub snugly
enough to center the wheel. THIS IS IMPORTANT!
Note: The center hole of a Honda rim is too small to fit
on some VWs, and the offset is wrong.
Q:What are the current preferred tire choices for VWs?
A:It depends on what you want from a tire...Performance?
Long Life? Good dry cornering? Wet weather handling? Snow
Tires? Race? There is no single tire that will give you
everything.
This list is not intended to be an exhaustive list, but
just a very brief summary of people's top choices. It's
primarily geared towards watercooled FWD VWs, and
therefore may not be applicable to other types of cars.
For more info see the very lengthy faq.tires.survey.
Normal
Definition: A mix of city/highway driving on dry & wet
roads. Desired Characteristics: All round predictable
handling & braking, long life.
Bridgestone (?)
BFG Comp T/A HR4 M&S (?)
Snow
Definition: Used for driving on snow and ice covered roads.
Nokia Hakkapelitas (sp?)
Gislaved Frost
Perfomance
Definition: Higher speed driving, high cornering forces,
summer tires
Dry Only:
Yokahama A008
Dry & Some Wet:
Bridgestone RE 71
Yokohama AVS Intermediary
Bridgestone Comp T/A 3
Michelin MXX3, XGT-Z or XGT-V
Uniroyal RTT1's (radical tread)
Dry & Wet:
Dunlop SP8000 (replacement of the D40/M2) - Good but take
a while to wear in.
Race
Definition: Special purpose race tires (i.e., shaven,
slicks, mud, ...)
Hoosiers
BF Goodrich Comp TA R1 - 230 compound
Call (800) RACE BFG for info and
purchases
Bridgestone RE71R or RE71RAZ (autox, call Blackburn Racing,
Indianapolis (800))
Yokohama A008 RSII (autox)
Toyo Proxy RA-1 (autox, call GT Int'l, West LA)
Michelin ?Ralley? (the *only* real mud tire).
Comment from Mark Sirota:
>From: chrub@CAM.ORG (Chuck Rubin)
> Looking for some advice on tires for use in Autocross
(Solo2) in Canada
> competition on my 1990 Corrado. My friends are using
Toyos, Yokos and
> RE71s on their CRX's and Civics but noone is racing a
Corrado. My car's
> got Eibach springs and a Neuspeed rear antisway so
it's quite stiff.
The short answer is that what works well for one
car generally seems to work well for other similar
cars -- so since your friends are driving other
front-drive sedan-type cars and their tires work
well, they'll probably work well on your car too.
Out here, the BFGoodrich Comp T/A R1 230-compound
seems to be the tire to have. That's officially
the road racing compound, but this past week at
the National Championships in Salina, I pretty
much decided that they're all around better than
the 226 autocross compound, except perhaps on very
short courses or in very cold weather. The next
choices are the BFG 226-compound, or the Yoko
A008RSII. I know that the Toyo is a very popular
tire in Canada, but almost nobody uses it here.
It just can't hold a candle to the BFG and Yoko.
I don't know if you get a different version of it,
or a different version of the Yoko and BFG, or
what...
Since your car is stiff, another possibility is
the Hoosier Autocrosser. This is a very
lightweight bias-ply tire, which has tread and is
DOT- approved. However, don't even think about
using it on the street. It is not very puncture-
resistant (not much better than a slick), and
won't last long. It only works well on cars with
good camber control (stiffening a production car
is often good enough), and with wide wheels. It
drives *very* differently, being bias-ply -- you
need large slip angles, but the thing really
sticks in sweepers. It's not as hot in
transients. You need much more steering lock and
a lot more faith in the car, as well as the
aforementioned stiff suspension and wide wheels.
The incredibly light weight also helps in the
power department and on bumps. I don't know if it
is available in Canada, but you can try calling
Tom Reichel at Mid-Atlantic Motorsport in
Maryland. Tell him I sent you. His number is +1
410 825 6003.
I used to run my GTI and 914 on BFG's, and now run
the Formula Ford on Hoosier slicks.
Note from Ed: Check with the club's regulations on
which tire sizes are acceptable for the group you
want to run in. Often, to run in an auto-x stock
class you need to stick with the stock sized rims,
however you may change the tire sizes. In that
case you want to get the widest and least tall
tire (i.e., lowest aspect ratio) that fits. If you
are allowed to change rims, then you want to get
the rims with the smallest diameter but widest
that will fit (top speed is not important in auto-
x) with the widest and least tall tire. This will
lower your center of gravity but also provide you
with a better acceleration. Naturally, for street
use and other types of racing you other wheel and
tire combinations may be needed.
It's also a good idea to have your tires shaven a bit to
smooth out the outer shoulder.
Another issue to consider with racing tires is what rim
and tire size to get. For example, in stock auto-x class
you have to use the same rim size as OEM, but you are
free to use any size tire that will fit. For auto-x it is
therefore recommended to get the smallest diameter tire
that you can find. This will lower he car and provides a
bit more low end torque on the road, tires that heat up
quicker, less wheel/tire weight because top speed is not
an issue. If you are racing in SP class, then the
smallest (but widest rim) that will fit with the
appropriate tires is what you want.
Q:What are "standard" (factory) tire sizes for my VW?
A:The following tires sizes (see the r.a FAQ for how to
read these) result in equivalent circumferences and
standard on most passenger VWs over the years. The
implication of this list is that in principle (if you
have clearance!) you could upgrade your tire/rims by
traversing this list! The whole aim with changing to
different tire sizes is to stay within a reasonable
margin of the original tire diameter.
155/80-13 => Rabbit (1975-1978), Golf Diesel, maybe other
A2's
165/70-13 => Rabbit (1979-1984)
175/70-13 => Scirocco, Jetta, Rabbit GTI, optional for
Rabbit, most non- performance A2s, A3 Golf
185/55-15 => GTX (16V Jettas in Canada), 16V GLI
185/60-14 => Golf GTI, Jetta GLI (85-87) Carat (86-89),
Jetta (90-93), Scirocco 16V, A3 Golf
195/60-14 => Quantum, Passat, A3 Golf
205/55-14 => Golf GTI 16V (1987-1989)
195/50-15 => Golf GTI 16V (1990-), Jetta GLI/GTX 16V, Passat
GL (1991-)
195/50-15 => Corrado G60 (1991-1992)
205/50-15 => Passat Syncros G60 (1991 +), Canadian 1991
Passat GL
205/50-15 => All VR6 models; 5-bolt rim
215/50-15 => All Passat VR6 models; 5-bolt rim; 6" rim
Some non-factory combinations are:
205/60-13
215/45-15
Q:How can I tell the characteristics of a tire by just
looking at it?
A:This is not easy, but there are a few things you can tell
just by looking at the tread pattern. Most performance
dry street tires will have lots of big solid blocks (or
almost no pattern at all, such as in slick racing tires,
see A008). On some tires these blocks vary in size and
that's mostly done to reduce certain noise harmonics.
Directional or assymetric tires will have block patterns
that are oriented in a particular way and that differ
accross the width of the tire (typically you can infer
the tire's direction of rotation on these tires, e.g.,
the new line of P0, RE71).
To make these tires more drivable on wet roads, you will
see one or more big channels along the circumference to
funnel water away. Goodyear now markets this technology
heavily, though Continental now claims they invented it
first.
To make tires behave under slippery conditions (snow,
mud, ice), they will have small squigly cuts called
"brushes" within the major tire blocks. (Obviously I am
neglecting the tire compound here that is probably more
important than the tread pattern).
Most quality tires are made from a "segmented mold" which
means that you will see mold marks running accross the
width of the tread (othogonal to the direction of
rotation). "Budget" tires still use old style molds where
you have the whole tire made in two halves and you will
see a mold line running along in the center of the tread.
The shape of tires also differs between manufacturers.
Some tires have a square cross section: |__| (e.g.,
Pirelli P600) while others use more rounding towards the
tread: (__) (e.g., Michelin MXV). It's unclear which is
better. The square profiles assumes that the tire is
stiff enough not to flex too much, while the rounder
profile assume that the tire will roll sideways under
hard cornering and therefore these tires often have tread
patterns on the side of the tires. It's unclear which
works better in reality (though the above two examples
should be used for comparison).
Q:Will wider tires help my performance?
A:There is no straight answer! There are really three main
factors that determine handling (disregarding suspension
changes for now): 1) Frictional coefficient between the
tire and the road, 2) Contact patch size and geometry, 3)
Tire sidewall stiffness. If you keep the frictional
coefficient constant as well, you have two parameters to
play with: Width and Sidewall stiffness. Wider tires will
change the contact patch from an oval to a more elongated
oval, which generally improves handling, but increases
steering effort, and makes the car more prone to
aquaplaning (hydroplaning) in wet weather and in snow it
never gets to through the snow. In snow conditions the
best way to go is small rims (13" for A1 & A2) with a 165-
175/70/13 tire on it.
However, another, perhaps more important factor is
sidewall stiffness. The stiffer the sidewall, the less
the tire will flex sideways which improves turning,
transients, steering accuracy Therefore going from a
175/70-13 tire to a "plus 1" 185/60-14 or a "plus 2"
195/50-15 tire will elongate the contact patch, reduce
the sidewall height ==> increase side wall stiffness and
therefore improve handling. However changing from 185/60
to a 195/60 may or may not do much good: The contact
patch is more favorable but the sidewall is also
increased in height ==> more flex. Test by VW and EuroCar
have shown that an A2 GTI with 185/60 tires handles about
the same as one with 205/55. Note that they were using
the same car for this test, with the same suspension. (VW
sold the A2 GTIs with wider tires purely for looks and
customer demand despite the fact that it did little or no
good in handling). To make use of wider and lower profile
tires the suspension needs to be matched to the tires.
But there is more to it as well! Tires, even within one
type & size, may have different sidewall stiffness (e.g.
HR vs VR), and compound! A softer compound will grip
better, but wear faster.. Wider rims make a big
difference due to a better lateral support, effectively
increasing sidewall stiffness. NEVER use 5.5" on a 185/60
or wider tire; the wider the better, at least within
reason. A 7" rim would probably be ideal for a 195/50R15
tire for the street.
From Roy Kao: wider tires may make a marginal improvement
in transient cornering responses, but how often do you
make radicalattitude changes on the street?
In summary [From Mark S]:
Cost: worse
Ride quality: worse
Tramlining: worse
Handling quickness: better
Handling limits: better
Safety in standing water, mud, or snow: worse
Looks: better (imho)
Steering feel: probably worse
Braking: can't say for sure
Power application: probably worse
A lot of the above depend on tire choice, too. Note that
choice of tire will have a much much larger effect than
changing wheel size on handling. Alignment also has a
huge effect, as does tire pressure.
Q:What is a performance alignment?
A:A performance alignment means a little more toe out than
stock, for better turn in, and more negative camber than
stock, for obvious reasons. I wouldn't recommend it.
Unless you plan to devote you life to autocross (and
people do) you will not notice the difference.
This will however result in much quicker street tire wear
so you will have to balance this with your desire for
autocross. I would suggest getting everything else right
before you start worrying about alignment though.
However, call Eurotire for details about having a car
aligned to Andy King's specs. The mild neg. camber does
not show up much on the tire edges.
Note from Jan: this needs work. A performance set up can
be achieved w/o sacrificing tire wear by increasing
caster angle, which unfortunately is not adjustable on
most VWs.
See also the archives on alignment.
Q:What does toe-in, caster and camber mean and how do they
affect the car's handling?
A:This is borrowed from the "alignment" archive:
CAMBER:
The camber angle is the angle a tire makes with respect
to a vertical line.
Positive Camber = Tops of tires point outward. If you
look at the front of the car you'd see:
V
FRONTAL VIEW __ ( ) W ( ) __
Tire \ \ ---------- / / Tire
-- --
Too much positive camber ==> Tires wear on the OUTside
(away from the car) more than the inside.
Negative Camber = Tops of tires point inward.
Too much negative camber ==> Tires wear on the INside
more than the outside.
Camber affects directional stability and tire wear. A
difference between the front wheel camber settings will
cause your car to pull to one side. I also believe it
will cause torque steering to become more noticable. It
is therefore very important to keep camber for BOTH tires
as close as possible.
Your car will also perform differently with different
camber settings. For street use, follow manufacturer's
setting, for race use, use more negative camber
(basically so that the inboard tire will be flat on the
road in sharp curves). Naturally, more negative camber
will wear the insides of the tires quicker.
Note however that the terminology used is often very
confusing, here is a sample (for either a GTI or Scirocco
I think):
>--<
[Jan]
> Camber = -.17 to 0.83 Degrees; which seems to imply
that they want > positive camber (tops pointing AWAY).
That doesn't sound right.
> To make matter worse, in Greg Raven's book, when he
talks about
> 2.5 Degree Camber he means NEGATIVE camber = / \. Can
someone please help
> me out with this one?
[Mark]
Right. Negative camber helps cornering power and turn-
in. The reason that they recommend positive camber is to
ensure understeer for the "average" driver. At the end
of last season, I had settled on about 2.2 degrees
negative camber while I was autocrossing.
>--<
The rear camber is not normally adjustable on most FWD
VWs.
TOE:
Toe = distance between the front of the tires and their
rears.
Sometimes express by an angle instead.
(Negative Toe) = Toe OUT = distance between the front of
the tires > rears If you were to look from the TOP:
Front
================== Bumper
TOP VIEW __ __
Tire \ \ / / Tire
-- --
(Positive Toe) = Toe IN = distance between the front of
the tires < rears
Unlike the camber settings, the individual toe of each
front wheel is not as critical (because of the steering
mechanism), but the TOTAL toe is (Toe = distance rear -
distance front of tire). Usually only one side is
adjustable, which then results in the "crooked" steering
wheel problem.
For the rear wheels the individual toes are however
important. If that's off, your car will be driving "side
ways". But you do not have to worry about it because the
rear toe is not adjustable on most watercooled FWD VWs
(w/o special equipment).
Too much toe in or toe out will also wear your tires
prematurely. The wear pattern is called "feathering" and
it will show up as a slanted wear or zig-zag accross the
tread of your tires. If you were to take a cross section,
you'd see something like (a bit exagerated due to the
limitations of this format):
_ _ _ _ _
TIRE CROSS SECTION / |_/ |_/ |_/ |_/ |
| |
Also here things get a bit confusing:
>--<
[Jan]
> The specs for Toe are even more confusing: -15'+10' = -
.25 + .17 Degrees.
> I assume the "+" is used instead of a "+/-" which
results in:
> -.25 to -.08 degrees, a slight toe in, which is more
what I'd
> expect. (Greg Raven however recommends 1/8 inch [yes,
inch] of toe OUT).
[Mark]
Right. So negative is toe-in. The only car on the
market today that comes from the factory with toe-out is
the Acura NSX. Toe-out also helps turn-in, but does
increase tire wear and gives the car a little bump steer.
It may also wander a bit on the highway. I was running
1/8" (yes, inch) of toe-out during the autocross season,
but now I'm running zero toe.
The reason that toe is often given in inches is because
it's much easier to measure that way.
>--<
CASTER:
Caster = The angle your wheels pivot about wrt to the
vertical when you steer (= the angle of front
struts/shocks wrt to the vertical?).
__
/ \ SHOCK TOWER
SIDE VIEW //|
// | angle
STRUT //
O Wheel axle
Affects of caster: It keeps the wheels running in a
straight line and causes them to straighten when coming
out of a turn. Increasing caster also provides better
handling w/o the tire wear.
Too much caster causes hard steering, too little causes
your car to wander. Caster settings do not affect tire
wear.
If you look at a car from the side, caster is the angle
the front strut makes with a vertical line, similar to
the fork on a bicycle. When you turn, the axis of
rotation of the wheels is not perpendicular to the road,
but rather at an angle:
V
FRONTAL VIEW __ ( ) W ( ) __
TURNING LEFT Tire / / ---------- / / Tire
-- --
The result is that the tires "brace" themselves against
the cars sideways movement ==> better cornering! I
believe this is one of the reasons why a Corrado SLC
(with > 3 degrees of caster) feels more stable in a
straight line, and corners better than a G60 (with ~1
degree of caster) if you ignore the softer springs and
shocks of the SLC.
Caster angles are not easily adjustable on most A1-A3
VWs. So if some shop tells you they did, question their
abilities... Note: Still under investigation! By changing
the subframe to that used on an SLC, a greater caster
angle can be achieved. More drastic changes involves
moving the shock towers.
Q:My stock shocks are shot? What should I use to replace
them with?
A:VW shocks don't last very long (30-50k miles). The OEM
shocks are from Sachs or Boge (note: they merged in 1994)
and similar to the Boge ProGas shocks. Stiffer shocks
reduce roll, improve handling but also make the ride
harsher. Most competition & longer lasting shocks are
called "gas shocks" because they contain a gas filled
chamber that keeps the shock oil under pressure. This
pressurization prevents cavitation and foaming which
increase wear and reduces the shock's effectiveness.
A compromise to using stuff shocks is to use adjustable
shocks. Most popular competition oriented shock brands
are: Koni & Bilstein (debatable which is better), then
Tokico.
From M.SirotA: For non-competition, I'd rank them
Bilstein, Sachs, Boge, Koni, KYB (initial quality
problems), Tokico (harsh).
A note from ND's BBS: We have had many problems with
Tokico and do not sell them anymore except for some of
the jap cars. They use to have the worst warranty claim
problems. They had a plating problem on the shafts and
would turn down warranties saying customers were using
vise grips on the shafts. Now I have seen what vice grip
marks look like as we do get idiots who do that but these
were a manufacturer defect. So we decided not to sell
them anymore. Koni, Bilstein, Sachs and Boge have very
good warranty procedures and we will continue to offer
them to our customers.
[Note: Tokico Illuminas have reliability problems and a
particularly painful failure mode, but the non-
adjustables are probably fine.]
From M.SirotA: Koni makes three types of shocks: Red,
Sport Yellow, and Sport/SS. The Reds are the softest,
Yellow are next, and Sport/SS is the stiffest. The "SS"
stands for "Showroom Stock", as in the racing category.
The Sport/SS shocks are usually also yellow. Bilstein
makes at least two: The HD (Heavy Duty), the Sport and
the Race. The Sport is the stiffer one. To complicate
matters further, not all versions are available for all
applications, at least not off the shelf. And old shocks
can be revalved, or new custom ones can be made.
As with engine modifications that can be measured on a
dyno, suspension is very subjective as what may give you
the best lap time at the race track may make you VW
slower on a bumpy mountain road. That is why each persons
driving habits and location of most of their driving is
so important to a proper selection. Many VW owners
autocross in addition to regular street use and they may
sacrafice comfort to have a better handling car on the
track.
From the AutoTech Catalog:
Shock valving comparison chart
OE Soft Race
Stiff
------------------------------------------------------------
-
[<Sach Super/Bilst HD >]
[< Tokico HP >]
[< Tokico Illumina Adj >]
[< Bilstein Sport >]
[Bilstein Ralley/Race]
[< Bilstein Race
>]
See also the archives on Suspension_Mods
Sway bars: (Anti-roll bars)
Reduce side to side roll. Essentially they increase the
spring rate when you turn, but leave the bilateral
compression rates unchanged. This also means that ride
comfort is hardly affected, in general a win-win situation.
Most newer VW have sway bars, but aftermarket ones are
stiffer (thicker) and are attached better. I personally
prefer sway bars that mount in almost stock positions (e.g.,
VW, Neuspeed, AutoTech) because they are easy to install and
do not require major modifications. There are other bars
made by H&H and Suspension techniques that have gained some
following. The general recommendation is to change the rear
sway bar first to reduce oversteer, or to replace them both
simultaneously. More recent sentiment has shown that for
certain cars (Corrados) the front camber changes are
significant and a front roll bar is the first to change
rather then the rear. Always keep in mind the racing
regulations in this regards.
From M. Sirota:
Conventional wisdom says that changing the rear swaybar
is a good thing. A bigger rear sway bar will move the
handling more towards oversteer, and will also help in
putting the power down on the way out of corners because
it will help to keep the inside front tire planted.
However, empirical evidence for A1 & A2 VWs shows that a
big front sway bar helps quite a bit, probably because it
pays big dividends in limiting camber change. A big rear
bar might do the same, but I've never tried it since I
only raced my VW in Stock category, and it wasn't legal
to change the rear bar. In short, on an A1 or A2 VW in
Stock-category autocrossing (where you are not allowed to
change the rear bar), run as big a front bar as you can
find.
[At a later date he adds]: Talk with any SCCA Solo II
autocrosser who runs a VW successfully in the Stock
category. In Stock, you can play with the front bar but
not with the rear -- and the secret is to run as much
front bar as you can. Makes the car MUCH MUCH MUCH
faster, *and* easier to drive. It's a big win. This is
a well-known fact. If you're not racing, or you're racing
someplace where it's also okay to change the rear bar,
then I can't offer any particular advice -- except that
you need more roll stiffness than VW provides, for sure.
In an ideal world, we'd only have one sway bar, and it
would be in the rear for a FWD car. However, in reality,
we almost always use two. If you could change everything
else (suspension type, pickup points, spring rates,
damper rates, geometry, corner weights, ackerman, roll
centers, CG positions, and a host of other things) you
might be able to design a perfect system where a rear bar
only would be a good thing. However, this is generally
impossible on production cars, and so we end up using two
bars just so that we can reduce roll without completely
screwing up the handling balance. As a side note, I use
both bars on my Formula Ford, too. I find that even
though I can tune it to be neutral with just one bar, it
feels much better in transients with two, probably
because the roll *rate* is more similar at both ends that
way. And I think they use bars at both ends even on
Formula One cars.
Stress bars:
------------
Stress bars reduce body flex by connecting either the top of
the free standing shock towers, or by connecting the
mounting points of the "A" arms. A1 VWs are in most need of
a lower front stress bar, while all A1 & A2 VWs could
benefit from an upper strut tower stress bar. (A2 cars have
a lower subframe and therefore do not need a lower stress
bar).
The advantage in installation of Neuspeed stress bars over
the Autotech bars is that you are not required to work on
the inside of the wheel well. The Neuspeed bar comes with
these "nutserts" that essentially create a thread in the
shock tower to bolt the bar to. The Autotech bars, as I
recall, require you to put nuts on the bolts from the inside
of the wheel well (they do claim to be a more positive
structural connection, which may be so). The Neuspeed bars
have also been superb quality and finish-wise.
Sporttuning tip from AutoTech: One warning sign of excessive
chassis flex is stress cracking of paint around the upper
front strut towers. This may eventually lead to the shock
towers breaking through. Stressbars can eliviate this
problem while also reducing chassis movement.
The rear upper shock tower stress bar is mostly for
*extreme* race purposes. Robert Collins (see archives)
argues that the rear stress bar is pure hype.
The effect of a stress bar is somewhat subtle, and does not
always translate in a significant performance gains. Both
the lower and upper front sway bar have subtle effects. The
cars feels "calmer" there seem to be fewer vibration
transmitted, and the car feels more confident in turns.
Springs:
--------
Springs don't normally wear out. However, there are
competition oriented springs that usually also lower the car
or progressive rate springs that offer a soft ride for
normal cruizing but non-linearly stiffen up as they are
compressed.
One of the things to keep in mind is that springs and shocks
need to be matched to some degree or ride may suffer. Most
engineers are probably familiar with the equations of a
spring and damper combination. Depending on the selected
spring and damping constant (and mass) the combination will
either be underdamped, overdamped, or oscilatory. Using
sport shocks with stock springs may not always be the best
combination, nor may sport springs with soft shocks.
Sporttuning Tip from AutoTech: Do not cut or heat sag
springs to reduce ride height because it does not increase
spring rate increasing the chance of bottoming out and the
chance to damage the chassis. The problems associated with
these modifications include broken strut housings,
misalignments, and broken windshield due to body twist. Heat
sagging also causes the spring material to become brittle
reducing the life of the spring. Stayaway from bargain
springs that use substandard wires.
**WARNING**: Suspension changes will affect the way your
car handles, especially under emergency maneuvers. Therefore
it is highly advised that you familiarize yourself with your
car before you use it in normal traffic conditions. Taking a
performance oriented driving class sponsored by one of the
car clubs is therefore highly advised.
>>>THIS NEEDS TO BE IMPROVED/REWRITTEN A BIT. SUGGESTIONS?
KEEP it short....
BODY/INTERIOR
=============
Q:How can I make my car quieter? What kind of sound
insulation is available?
A:There are a variety of products available on the market
that you either glue on the car's inner body panells or
spray into cavities. These products are available from
either car audio stores, or electronic stores. Do shop
around because price varies alot.
The effects of this insulation varies with the type of
material used and how and where it was installed.
Generally, the more you cover up, sometimes even doubling
up in certain areas, the greater reduction in noise. It
will also improve the sound quality of your car due to
the fact you have lowered the resonance frequency.
VWs generally produce most of their noise in the engine
compartment, followed by the entire exhaust system, the
wheel wells (rear), and after that it's probably a toss
up whether your doors or your roof makes the most noise.
For the more recent models, VW actually did a fairly good
job at insulating the car, however, there is always room
for improvement.
Start with the easily accessible areas that have bare
sheet metal, and that sound "tinny" when struck. Most
people start by insulating the trunk floor, rear wheel
wells, the spare wheel well, and underneath the rear
seat. Those areas are right above the muffler or the
wheels with little or no insulation. In my Corrado G60, I
noticed a reduction in buzzing coming from the rear. The
car is now noticeably quieter in the rear versus the
front, while previously it was about the same. Some have
reported results up to 10 dBa reduction, which is rather
significant (a 3dB reduction = 1/2 the noise).
If you are more ambitious, go underneath the carpets as
well. However, depending on the model of the car, VW
probably beat you to it already and it's unclear whether
it'll make much of a difference.
The next areas to treat are harder. If your car does not
have foam underneath the hood, add it. Next try
insulating the fire wall, but be aware that that area
gets very hot and you need suitable materials for that
area.
The top is like a bloody drum, in some respects, and
anything done here to deaden it or change the harmonic
frequency helps. Note that the foam insulation that vw
uses deteriorates after a period of time, especially the
headliner.
Cut the mats to size, than pull of the adhesive cover and
stick it to the body panel. Some products require a heat
gun (hair dryer works too) to establish a firm bond, or
to get the material sufficiently pliable. Some apply
additional glue, such as 3M "Spray 99 adhesive" to get a
good bond.
Probably the most popular product in the USA is that made
by Dynamat. Another brand name with a similar product is
AccuMat by Scoshe Industries. Both Dynamat and AccuMat
sell a variety of types, the thin sheets are generally
for covering body panels, the thicker for under carpets,
and a high temp mat/foam sheet that can be used in the
engine compartment. Other brand names are: Kentamat,
Sonex, a foam padding, designed much like the walls of
an anechoic chamber, available in various thicknesses and
densities, and used to deaden or absorb sound in rooms,
chambers, or instrument areas.
Dynamat is some kind of asphalt sheet with glue on one
side, while AccuMat is made out of latex and the thicker
ones out of foam. Some speculate that Dynamat is nothing
more than Bitumen roofing paper, and therefore any dense
material would work. Some have had limited success with
using asphalt roofing material such as "Elastophene Flam"
which is an SBF membrane roofing material (it's black,
heavy, fireproof, 1/8" thick and relatively cheap) or
simple vinyl floor tyles which the AccuMat thin product
resembles.
I have used the thin sheets from both Dynamat and
Accumat, and they both have pros and cons. Accumat costs
more, adheres better but does not dampen as well. Dynamat
does not adhere well at all (unless you use a heat gun or
spray on adhesive), dampen better than Accumat
(subjective opinion) but out of the box, Dynamat STINKS
majorly. Applying this fresh dynamat over a surface that
get hot (i.e., above the exhaust system) will noticeable
smell up your car. The problem goes away over time, but
it's better if you leave the sheets to bake and air out
in the sun for a couple of weeks. Dynamat does sell a low
oder version, but that's even more expensive and smaller
than their regular sheets.
ADVOTECH (CA) sells a product called RattleTrap which is
a rubbery goo (it reminded me a bit of Plummers' Putty
actually) you squeeze into cavities that buzz.
Q: Is moving my battery to the trunk a good idea? What
effect will it have?
A:[From Jeff Mayzurk]: Yeah, it's a great idea. I did it in
my Scirocco and was very pleased with the results. Before
you do it, though, take your car to a local truck stop
(or any other certified scale) and get the weight for
both axles, and then compare afterwards so you can figure
out how much of a difference it made.
In Greg Raven's "Water-Cooled, Front-Drive Performance
Handbook," he discusses the effects of moving the
battery on weight distribution. In his example, moving
the forty pound battery (mine weighs 38 lbs.) to the rear
moves the center of gravity back only 1.9 inches, but has
a much larger effect on weight distribution.
In my car, I bought a $10 plastic battery box, about 20
feet of 2-ga wire, and a few battery terminals. It's
mounted right behind the rear seat on the passenger side,
and is grounded at the right-rear seatbelt mount
(underneath the cushion). I ran the positive cable along
the doorsill, underneath the carpet, through a grommet in
the firewall, and to the alternator. After adding
additional engine-chassis ground cables, I've had
absolutely no problems with charging.
Holes can be drilled through the floor of the trunk
inside of the battery box between the battery box wall
and the battery. Make sure nothing is in the way below
the floor of the trunk when you drill the holes.
If you know your car extremely well, you will notice the
difference right away -- I did. You have the be really
sensitive to your car's behavior in transitions, but the
difference is there. My car rides better and dives less
under braking. Handling feels just slightly more neutral
overall, but traction under full throttle in low gears is
more of a problem now. (This is the only drawback I can
think of, and is definitely something to consider if you
have a very light car with a strong motor.)
By the way, make sure you have some provision for holding
the battery down in the event of a rollover. If your car
ever gets upside down (god forbid), you don't want that
forty-pound weight flying around in the cockpit.
NOTE: Relocating the battery may put you in a different
auto-x category!
MISCELLANEA
>>>> SUGGESTIONS/COMMENTS/CORRECTIONS? send e-mail to above
address
Contributors (not exhaustive):
------------------------------
Note: Quoted contributions imply possible conflicting pieces
of advise with other contributors.
See the lists in the other FAQs.
mgm@royko.Chicago.COM (Marty Masters)
Blake Sobiloff <sobiloff@lap.umd.edu>
jay.mitchell@the-matrix.com (Jay Mitchell)
Jonathan Dove <jdove@gsvms2.cc.gasou.edu>
jstulen@eis.dofasco.ca (James Stulen)
Jeffrey M. Mayzurk <ELJEFE@utxvms.cc.utexas.edu>
drbob27@aol.com (Bob April)
welty@balltown.cma.com (richard welty)
e0ewqbwu@tuzo.erin.utoronto.ca (Roy Kao)
<drbob27@aol.com> (Bob April)
Michael R. Kim <mrkim@uci.edu>
priest@flame.engr.sgi.com (Ed Priest)
rchambers@aol.com (RChambers)
ptong12@ursa.calvin.edu (Peter Tong) '82 2.0 8v cabby --
highly modified
TURBOTIM at ND's BBS (Tim Hildebrand)
lindi@monk.bose.com (Matt Lindi)
cmhewitt@mtu.edu (Chad Hewitt)
harry@alsys.com (Harry Kimura @ignite)
donald@sq.sq.com (Donald Teed)
mbernier@aol.com (MBernier)
Bryan D. Boyle bdboyle@erenj.com
whong@ida.org (William Hong)
Michael R. Kim mrkim@uci.edu
a-mikem@ac.tandem.com (Michael McKay)
soo@bmerh989.bnr.ca (Wei Soo)
chrub@CAM.ORG (Chuck Rubin)
cocw@hk.super.net (Mr Chun Wong)
monster16v@aol.com (MONSTER16V)
MICHAEL H. CHIN" <MHC@ussu.Ciba.Com>
h2only@aol.com (H2ONLY)
------------------------------------------------------------
--------
Disclaimer: My employer has nothing to do with this. Use any
info in this posting at your OWN risk. This is public
information and should not be dissiminated for profit.
--
o ___|___ [\\] | Jan Vandenbrande jan@lipari.usc.edu
__0 /\0/ /-------\ _ | http://alicudi.usc.edu:80/~jan/
\<,_ O \\ (_________) .#/_\_. | If you are still in control, you are
(_)/ (_) // [_] [_] |_(_)_| | not going fast enough.
User Contributions:
[ Usenet FAQs | Web FAQs | Documents | RFC Index ]
Send corrections/additions to the FAQ Maintainer: jan@ug.eds.com (Jan Vandenbrande)
Last Update March 27 2014 @ 02:11 PM
|
rec.autos.vw [W] PERFORMANCE, FREQUENTLY ASKED QUESTION (FAQ)
Search the FAQ Archives
N - O - P - Q - R - S - T - U - V - W - X - Y - Z
rec.autos.vw [W] PERFORMANCE, FREQUENTLY ASKED QUESTION (FAQ)
[ Usenet FAQs | Web FAQs | Documents | RFC Index | Cities ]
Comment about this article, ask questions, or add new information about this topic: