jcmbird

just wondering , for track times, if I increased frt weight when lowering c5 with big sway bars [t1, pfadt], would it help under steer with stock wheels instead of smaller rears and larger fronts tires [square] set up. What is best wheel and tire [size] combo for track ? thanks.

Bill Dearborn

Not sure how you intend to increase front weight by adding sway bars? If you are adding weight (lead bars, etc) to the front that will increase the understeer. Cars with a lot of front weight plow like mad.

Try this driving technique first. Do all your braking in a straight line and just as you are letting off the brake start to turn the steering wheel. The way to tell if you are doing this is to notice the front end lift when you take your foot off the brake. If the steering wheel has started roatating when the front end lifts you are on the money. Now complete your turn in and as you approach the apex you should be squeezing on the throttle and going to full throttle as you pass the apex. If you cannot get enough steering input into the car (pushing) and run out of room on the exit that means you cheated on the turn in and turned in too soon so the next time through that turn go a little deeper before your turn in. As you get a little more experience you can try more advanced techniques (trail braking, throttle blips, slightly rocking the steering while turning, etc) to enter faster with an early apex while using a late apex track out.

On stock tires the C5 can be a little tail happy under trailing throttle conditions so you need to keep some power to the rear wheels after you make your turn in just to keep the *** end from passing the front.

Bill

AU N EGL

How old are your tires?

When I ran a square tire set up the car understeered like crazy, Had to learn how to take corners differently. Almost had to feather the throttle so the rear would come around mid corners.

The best tires are what you get use too.

emf

Yes, Lowering the front end / jacking the rear end will help with understeer, but so will a bunch of other things. What's "best" comes down to driver preference, and the track -- some people look at a square tire setup, others adjust by adjusting the car's weight.
Obligatory over/understeer correction sheet here:

**Understeer Corrections
Push, plowing, front tires slide out first.
Usually slight understeer is safer.
Raise front tire pressure.
Lower rear tire pressure.
Soften front shocks. Stiffen Bump.
Stiffen rear shocks.
Lower front end.
Raise rear end.
Widen front track.
Install shorter front tires.
Install taller rear tires.
Install wider front tires.
Install narrower rear tires.
Soften front sway bar.
Stiffen rear sway bar.
More front toe out.
Reduce rear toe in slightly.
Increase front negative camber.
Increase positive caster.
Soften front springs.
Stiffen rear springs.
May need more front suspension travel.
Install wider front wheels.
Use softer front compound if possible.
Use harder rear compound if possible.
Remove weight from front of vehicle.
Add weight to rear of vehicle.
Drive a different line.
Use weight transfer to your advantage.
High Speed. Increase front wing downforce.
Too much front brake.
Vehicle is TWITCHY at limit and hard to keep
ahead of in the steering department.
Lower front and rear tire pressures slightly.
Suspension may be too stiff.
Shocks may be set too firm.
Tires may be old or hard.
Vehicle may not have enough suspension travel.
Vehicle may have a toe problem front or rear.
Increase negative camber front and rear if possible.

**Oversteer Corrections.
Loose, rear tires slide out first.
Oversteer can be dangerous, especially at high speeds.
Lower front tire pressure.
Raise rear tire pressure.
Stiffen front shocks.
Soften rear shocks.
Raise front end.
Lower rear end.
Reduce rear track.
Install taller front tires.
Install shorter rear tires.
Install narrower front tires.
Install wider rear tires.
Stiffen front sway bar.
Soften rear sway bar.
More front toe in.
Increase rear toe in.
Reduce front negative camber.
Reduce positive caster.
Stiffen front springs.
Soften rear springs.
May need more rear suspension travel.
Install wider rear wheels.
Use harder front compound if possible.
Use softer rear compound if possible.
Add weight to front of vehicle.
Remove weight from rear of vehicle.
Driver may be going in too deep.
Driver may be getting on the throttle to early.
High Speed. Increase rear wing downforce.
Too much rear brake.
Vehicle slides and is easy to drive at limit but
does not corner to full potential.
Raise front and rear tire pressures slightly.
Suspension may be too soft.
Shocks may be too soft.
Roll centers may be too high.
Lower vehicle.
Tires may be too hard.
Widen track front & rear.



A properly set up vehicle will usually push slightly on corner entry, be fairly neutral at the apex (STEADY STATE) and exhibit slight power oversteer on corner exit. Tight courses may require more oversteer, fast tracks understeer.**