Suspension vs. Tires vs. Balance

[Mitch <mitchman@owt.com>]

Bob Tillman touched on this but I'm not sure he really explained it.  No
matter what type of tire you have on your car you can tune the suspension
to make the cars handling neutral.  Neutral handling is a very interesting
thing.  I owned an '84 RX-7 before my GLX.  I installed a fully adjustable
coil-over setup with adjustable swaybars front and rear.  The problem was,
how to adjust the suspension for neutral handling.  What was "neutral
handling"?  After chasing setup on the autocross course for a year, I found
enlightenment.  I drove my fathers '92 Miata in an autocross, suddenly it
was very obvious what neutral handling was.  I could finally "late brake"
or "left foot brake" the car and really see a difference in how the car
handled.  Let me see if I can explain balance even better.

In my experience "balance" changes with the speed of the car.  That's why
setting a car up for a road course is much different than setting it up for
an autocross.  Most autocross setups will cause the car to be too loose
(oversteer)for use on a road course.  In fact, most autocross setups (not
stock autocross but SP, P or modified) are ususally to agressive (too much
oversteer) to work well on the street.  The car is too loose in 50mph+
corners. Our stock VW's have a low speed push (understeer) but handle great
at high speeds.  I'd love to try my stock GLX on a fast road course.  I bet
it'd work great, with maybe a touch of understeer in the tighter corners.

Again, in my experience, once you decide what you are going to set the car
up for (what speed you are going to corner at) than you can change the
balance.  I think the ideal setup should let you control the car like this:


1. Enter the corner by doing all your braking while the car is going
straight (right foot braking) This should cause the car to slightly
oversteer caused by letting off the brakes before you turn-in.  The car is
still slightly nose heavy from braking.

2. Enter the corner by letting off the brake after you have started to
turn-in. This should cause a fair amount of oversteer because "late
braking" has all the weight transfered to the front tires when you turn-in.
This is good for tight corners at the end of a fast section.

3. Enter the corner by left foot braking and letting off the brake as you
turn-in.  This should let you brake deeper into the corner than condition
#1.  The backend shouldn't come out.  This is good for fast corners to keep
the rear end in check.  You are still on the gas as you start braking.
Slowly let off the gas as you apply more brake.  This keeps weight transfer
to a minimum.

This has been my experience.  I haven't mastered it by any means!  :)  It's
difficult to judge the speed of a corner if you only get to walk the course
(autocross).  I think this is where experience comes into play.  I
encourage anyone that is trying to "tune" their car to go drive a stock
Miata or a other "good handling" car.  It will help you understand what
your trying to acheive with your own cars suspension.

***In answer to the Suspension vs Tires.  I'd go with the suspension.  A
balanced car will always improve your times and improve your driving
skills.  New tires will just improve the grip, the balance will stay the
same and you will still be used to driving a balanced car.  If you are
racing stock in autocross, you will be buying "R" compound tires anyway so
bringing autocrossers into the discussion is a moot point.

Just my two cents.  (WOW, I wrote a novel!!)

Mitch Lewis
'97 GLX






>Hi Andy -
>
>I'm replying to the list, since I _can't_ let you have the
>last public word on this!  ;)  However I agree that this
>isn't going to be decicided on the list.  I just want to
>promote the "what are you trying to get out of this" point
>of view.
>
>I agree with the person who asked: what do you want?  A
>faster car?  Or do you want a more fun-to-drive car?  I
>can't argue that good tires on the stock suspension may be
>faster than the GAs with an aftermarket suspension.
>
>However I _can_ argue that a better-balanced suspension,
>even with crummy tires, can be more fun to drive than good
>tires with the stock suspension.
>
>I guess we're getting back to the most basic issue: not
>everybody wants the same thing out of their cars.  _I_
>haven't autocrossed yet (but I may hit a road course next
>summer); but I want more enjoyable driving on my daily
>100-mile commute.  A few extra tenths of a G won't make much
>of a difference to me on that exit ramp; however a
>better-balanced car will put a bigger smile on my face.
>
>The autocrossers, though, will (quite rightly) argue that
>those precious fractions of a second are worth a lot!
>Especially if you can get them without putting your car into
>a different class.  I totally agree that for them the tires
>are definitely the first priority.
>
>>   We all agree on that point.  The question is:  can the same car
>>   with aftermarket suspension & stock GAs do better than with
>>   stock suspension & hi perf tires?
>
>Here's where (what I assume to be) your Autocross preference
>deviates from my "fun-to-drive" preference.
>
>>   Unfortunately, with an aftermarket suspension and the GAs, I'm
>>   not sure if it's any safer, since the GAs is rated at about
>>   130mph.  I'm not sure if I want to go that fast knowing that
>>   the GAs may not be to handle the braking chores.
>
>Since we're debating ;)  I think that I've only had my car
>above 130 once; I rarely go above 120.  I'll go above 100 a
>couple times a week, but only for about 15 seconds at a
>time.  I'd argue that for that style of driving the "H"
>rating is fine.
>
>> > 4) The big reason: new tires with stock suspension won't cure the
>> > pushing; it'll just raise the threshold higher.  A new suspension will
>> > give you a better balanced, more tossable car which is
>> > *more*fun*to*drive* than an understeering, pushing, plowing, floaty
>> > car.
>>
>>   You mean as opposed to a car with a firmly sprung and nicely
>>   damped suspension that *still* understeer and push and plow
>>   because it's on Eagle GAs?  |-)  At least when you're
>>   understeering and pushing and plowing, the suspension would be
>>   nicely controlled.  |-)
>
>Yes, let's warm up those armchairs! ;)  I still claim that
>the GAs won't push and plow with a properly balanced
>suspension.  They'll just have lower cornering limits all
>around.  I know this because I had aftermarket sway bars
>with the stock GAs, and enjoyed much improved balance.
>
>>   On the flip side of the coin, a GTI VR6 with firmer suspension
>>   and more roll stiffness will exert more cornering forces
>>   (lateral & downward), making the GAs roll onto their sidewall
>>   even more.  Ask the people that I had given my old GAs to what
>>   those tires' shoulders look like.
>
>Granted, but I argue that my swaybar experience still
>yielded a better balanced car.  And since the GAs wear so
>slowly, is it _truly_ a bad thing when you can find
>something that wears them out faster?  :) :)
>
>>   [ I think we should stop now, since I think the person who asked
>>   the question is now very sorry that he asked.  He is currently
>>   more confused than when he started out.  |-) ]
>
>Oh come on!  You're going to claim the last public word?  :)
>
>Cheers,
>- Bob T.
>  '96 GTI VR6 118k miles Shine, Yoko AVS, Schrick 268
>--
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