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Author Topic:   Wheel Scrub
poboy2
Dirt Freak

Total posts: 219
posted October 10, 2001 10:55 PM
Okay, last year a guy told me that putting 68-72 chevelle rotors on our metric car would widen the front by 2.5 inches. I did this and also used 2 in offset wheels in the front as well. This got the frontend very wide,but it also gave the frontend alot of wheel scrub (distance that a wheel travels front to back, while turning). All year, we were fighting a push condition with the car. We tried alot of differant thing to fix it. Out spring and shock set up was identical to the majority of the faster cars at the track. Just wondering if the extreme wheel scrub could cause that condition.

c21
Dirt Freak

Total posts: 346
posted October 11, 2001 10:09 AM
Not exactly clear on how much of a change you made, but be aware that moving your wheel farther away from the spring effectivly makes it a lighter spring (ie. reduces wheel-spring-rate).... and .... multiplys the effect your castor has on jacking or unjacking that corner of your car. You may want to consider calculating what your wheel-spring-rate was (before the change) and then increasing your front spring rates to make your current wheel-spring-rate the same as it was and then sort out your push from there.
Good Luck

r19v
Dirt Roller

Total posts: 19
posted October 12, 2001 01:08 AM
Poboy2,

I have raced on dirt and asphalt both. I built a car similar to yours and had the same problem on dirt. (Worked great on asphalt.) I don't think your problem has anything to do with scrub radius. We had a push on entry, worse on wet, better on tacky, and better yet on dry, and best when a lot of rubber layed down on track. What we found out was the front was too wide. I think you are not getting enough roll and hence no side bite. Side bite is critical to a dirt car. Try putting 4 offs on front and see if it gets better. If it does then go back to your original rotors. I'd bet it would get better yet. Lower and wider is better on asphalt, but not on dirt.

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