Do I just have to learn how to drive or is there some setup I can do to make my wicked under steer go away?

Background, (1988 stock coupe)

I come into a hard corner (right or left does not matter)
Apply breaks at last second (trying to force more pressure on front tires for traction)
Run most of corner fine
Coming out of last half of apex with gas floored and the damn thing goes straight (over steer)

Sooooo, am I doing something wrong? If so, what? Could it be my tires (Firestone Firehawks 275/40/17 (?))

What kind of tires do you autocross guys/gals use?

Please help, the noise it makes as it pushes through the corner is really scary, not for me, but for the pedestrians on the street.

Thanks
:cry

 

What are your tire pressures?

Are you experiencing body lean?

How many miles on your car? Things could be wearing out like bushings, shocks, springs.

I've got Firehawks as well and don't have an oversteer problem. For auto-x (and I'm no expert, check on the racing forum for the guys that really know what's up) I run 36 Front 34 Rear.

 

First of all, that doesnt sound like something you should be doing on Public Streets, not safe, and if you hurt someone it will give us Vette owners a bad name, not to mention, you can really hurt your car doing this. Enough lecturing.

There are many reasons for the dynamics of understeer\oversteer. THe only way to diagnose it is one a course where the conditions are consistent, and can be repeated. (Auto-X, Road course, skidpad).

A public street corner can have dirt, debris, water, oil, and inconsistent surfaces. All which can contribute to understeer.

Next is your driving ability, even a race tuned C5R can be made to push if not driven right. You need to practice your skills. Its not just speed and mechanical grip from tires, its weight transfer, roll physics, hitting the apex, and rolling on the throttle while the car is at the apex. Mashing the throttle full open in any car (except for a computer controlled F1) will cause the weight to transfer to the rear wheels, lightening the fronts, and causing understeer. There are ways to tune the chassis to somewhat compensate for this and allow heavier throttle application, but thats probably not within your scope for this application.

I would suggest finding an Auto-X and taking a ride with an instructor and he will drive your same car through the corner correctly, efficiently, and more quickly than you.

Its all technique, and finding the limit of your car and not surpassing it, just flirting with it!

Make sure the car is mechanically sound of course- properly working shocks, straight rollbars (not tweaked), good tires with proper inflation, and fresh brakes.

Drive into the corners, use enough braking force to slow the car down to cornering speed, without upsetting the weight balance (rake), basically you want the weight to transfer, but not with whellspin or excessive nosedive. Go through the apex under neutral balance and make sure to transition from braking to throttle with as neutral balance as possible, you really dont want to upset the car here, just roll the throttle on smoothly and point the car towards the outside of the next straight. Once its all lined up, you can be very aggressive on the throttle. Practice it at a safe speed a few times, then slowly increase the speed\exit throttle until you find the limit of adhesion (understeer\oversteer begins) once you have mastered it, you can compensate for understeer with, believe it or not, more throttle applied at the right time or perhaps an earlier apex or later apex.

The common misconception about driving fast for the layman racers is that they do not understand the racers addage of "slower is faster"! Once you accept, and understand that phrase, it will all make sense, and you will be on your way.

Buy yourself a good computer with a steering wheel and a good racesim to really understand the dynamics. You can also by a book by Carroll Shelby called Drive to Win or Engineer to Win.


[Modified by GusBustamanteJr, 11:48 AM 7/23/2002]


[Modified by GusBustamanteJr, 11:50 AM 7/23/2002]

 

Lecture is noted, and put away for future referance. I never thought of the consequences(sp) of my actions in the sence of (other) personal injury.

I just like the feeling of a well traveled corner. You said a mouth full and I will be looking for an Auto-Cross club around here to tone my skills with and get some more advice.

Thanks.

PS. Any clubs in the Ottawa, Ontario, Canada region.

 

I may have some insight. First try driving smoother, trail break a little into the turn. Don't slam the breaks on. Auto-x will help to teach good methods. There are a few mods you can do to make the car handle better. However, these are best applied after you improve your driving skills. I still push the front a little during Auto-x's, but I am improving.

DO NOT PRACTICE SKILLS ON THE STREET! :nono:

Not a lecture, but be safe. I am here for any insight you may need. Try looking up the SCCA on line to find a club near you. It's a blast and dosen't cost much.

:cheers:

 

ok.

1. Drive smother (check)
2. Don't do this on the street (check)
3. Look up SCCA on the net (ch--- damn SCCA = sports car club of "America")

Ok I live in Canada, any clubs with the SCCA appeal up north??

 

Being that your in Canada is it possible that there is snow on the street?
(LOL).
Basically you need to stiffen the rear. Shocks worn?, what size sway bars?.

 

NASA - National Auto Sport Association
NCCC - NATIONAL COUNCIL OF CORVETTE CLUBS

That sucks! I never thought about it before, but all of these organizations stop at the border don't they.

I would think that you guys in the 'Great North' would have some type of organization(s) for amateur enthusiasts (racers)

As for the understeer, it has been pretty well been covered. smooth is the word. Imagine a cup of very hot tea in your lap that you don't want to spill. :D

 

Well, if you make the mistake of getting Sumatomo tires the way I did, you're lucky to be able to keep any end of the car hooked up. However, to make this a constructive post, I found on my Camaro that adjustable sway bars was a good way to balance understeer and oversteer.

Corvette's usually have an oversteer problem because of the more 50-50 weight bias verses F-bodies.

FWIW,

BIG JIM

 

:lol:

Try checking your air pressure on all four tires. On almost all vettes you should run about 2-4 pounds less in the rear.
For example:

Front: 40
Rear: 36

You will be surprised how a few pounds makes a difference.
You'll need to play with it to see what works best on your road conditions, driving style, and suspension configuration.

Autocross is best place to experiment with it.
:yesnod:

 

Wax on, Wax off. :lol:
Mike, any luck finding that O2 sensor info?