I have a drag race car and we have bump steer problems that may be different from track cars. When we pull the front wheels off the ground they hang down some before motion limiters stop them from falling anymore. If the tie rods are not perfectly horizontal to the suspension at neutral, then the car will have more problems. For instance, if the front end sits real low and the steering is mounted low, then the tire rod has to angle up to the tire. When the front end comes up, the wheels drop and the tie rods push the tires out. So you have a toe out condition as soon as the tires touch the ground. Then the suspension is compressed beyond neutral forcing the tires into a toe in condition. Thats better than toe out. But usually the car will lift again and bounce some, going back and fourth between toe out and toe in.
This takes place in fractions of a second. And as you adjust for one, the other occurs and the handling completely changes. Many race cars have been destroyed by this condition.
If you want to see if your car has bump steer, its an easy check. put a jack under the front of the car as you jack it up, watch and see if the tires start to toe in or out. You can put a straight edge against the tire and wheel and mark the location on the ground. Then let the jack down and get a friend or two to push down on the front of the car. Check the toe out / in at that position.
If your front end has good geometry, then the changes will be very little either way from neutral. I can see where hard accelerating and then hard breaking would make for a very hairy ride.
I have restraining straps on my race car to keep the tires from moving more than a couple of inches. The front end hits a little harder, but doesn't get as squarely as others.
Good luck and have fun.

 

That's been my experience with my RSX-S. After I installed the Mugen sport suspension, the rear bump steer diminished greatly. The stiffer strut and spring did the job.

 

Do the C6R vettes run a coilover type suspension or do they also use a form of the leaf springs? Another concern, I've heard that even the Z06 vette uses the run flat tires, I've heard those things are terrible on road courses as they don't heat right, are hard to keep consistent temps., and overall just don't act as predictiable and add the same amount of grip as a regular tire. Is this true, or just an inflation of a small problem.

Ryan B.

 

The C6R uses coilovers for the very reasons that have been discussed here. It is hard to find many different spring rates in leaf springs. As fars the run-flats go I don't know about heating and cooling properties, but they are quite heavy and have less feel from their extremely hard sidewalls. Is the actual tread compound different then a corresponding non-runflat?

 

For the sake of adjustability and off the shelf parts (as race parts go), the C6R uses coil overs. However, if the parts were available I suspect they would retain the leaves.

 

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