Roll Center design theory

[Salt Racer]

...It also picked up an odd twitchyness at times on rougher surfaces...Our G-5 package test car feels a little bit better at +5.5*....

I'm almost certain that difference in scrub radius has a lot to do with it as well. GM did a fantastic job designing C5 knuckles and hubs.

I'm currently running +6.0* on my Riviera. Feels better on street compared to stock +4.0* Never ran it at track with stock alignment so I have no comparable result. Scrub radius is currently 2.38", which isn't terrible for a '60s car. I might try +7.0* at Buttonwillow just to aid camber angle a little.


Dennis,
The spindles you currently have must be a lot taller than what we thought. But I'm pretty sure you'll be getting the new ones made anyway, so just be sure to take accurate measurements on chassis pickup points. Those are what determines new UBJ/LBJ locations. You can still re-measure your existing spindles for academic purpose.



If you still have access to Perf Trend, try backing out a little on KPI. 14* is very steep. Its drawbacks may not be worth the small gain in scrub radius.

I don't know what your long term plan is with your car, but scrub radius can be reduced later when you can afford new rims and longer A-arms. If you have the slightest intention of doing this somewhere in your head, plan ahead and redesign spindles accordingly so you wouldn't have to have two sets of custom spindles made.

[kmracer]

wow. you guys rock.

[David Pozzi]

I think I'll move this thread to the Tech section. Thanks for finding this one!

[kmracer]

yea, there was actually a link to it on lat-g. great stuff. this is the reason i love this site.