[Ron Sutton]

Originally Posted by FETorino

g. Any parts of steering geometry: KPI, Caster, Caster Gain, Camber, Camber gain, Ackerman, toe, etc.
Since I believe I have a low amount of scrub in seeking a KPI/Castor split to gain grip on those tiny 285s I have up front is it more advantageous to simply gain castor by changing my UCA or would a spindle with a lower KPI angle be a better route. I realize the smaller angle of the spindle would create more scrub but since I have a high inside offset I would still be in what you consider the "low" range.

Tiny 285's

In my experience, keeping the KPI you have to keep the scrub radius lower is by far the smarter route. It's a little like widening the track width ... in that you're affecting the handling at the source, versus "trying to deal with it" afterwards with suspension tuning.

Same with scrub radius. If the car has a larger scrub radius, you will do a lot of tuning "trying to deal with it" afterwards with suspension changes. So no, I wouldn't change spindles, I would change or modify your UCA and/or LCA to achieve more caster.

Once I know the actual scrub radius ... and the "for sure" KPI of your spindle ... I can give you two caster targets. One that would "ok" for most road course corners ... and one that would turn on a dime regardless of corner radius.

Since we have been given 3 KPI different numbers on the C6 spindle ... until we're "sure" of the KPI ... and scrub radius ... it's hard to say anything with certainty. I can teach you a "car guy" way of determining your scrub radius ... if you want to measure scrub radius yourself.


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