You can get a pretty good approximation of the effective rate of the factory bars using the diameter and arm length.
A 1.25" front bar is overkill if you're running springs of a more "modern" spring rate and will probably lead to poor turn-in and understeer.
With 550# front springs I'd probably start with around a 1.125" bar and go from there, my guess is that turn in will be best with a 1" to 1.125" front bar with those 550# front springs, but it depends on tire & driving preference too.
I'm running a 15/16" front bar with my 750# springs. Started with my old 1.25" front bar and the turn in was slow and had lots of understeer, 1.125" was better, and 15/16" was the best.
I do want one of Mark's adjustable A-body frame-link rear bars when they come out so I can fine-tune things...
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1969 Chevelle
Old setup: Procharged/intercooled/EFI 353 SBC, TKO, ATS/SPC/Global West suspension, C6 brakes & hydroboost.
In progress: LS2, 3.0 Whipple, T56 Magnum, torque arm & watts link, Wilwood Aero6/4 brakes, Mk60 ABS, Vaporworx, floater 9" rear, etc.
Last edited by Blown353; 11-03-2008 at 09:51 PM.
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