Recommended Spring Rates for ITS Road Racing?

[kirkm27]

I just raced my 71 240Z in SCCA competition this weekend for the first time. I got KILLED! I probably have the wrong springs in the car because it pushes (understeer) like a dump truck. I followed the recommendations of my strut/spring supplier, but I won't mention any names. I think I had way too much spring in both front and rear. Any recommendations from the members who race their Z's in IT type road racing? I use coilovers on all four corners and have a 1 1/8" bar in front and will be adding a 22mm bar in the rear. New struts on all four corners, but not adjustable. I had the proper camber, caster, and toe for front and rear set also.


Thanks in advance for the help,

Kirk

[Tom Donnelly]

I'll have to check my documentation when I get home. Understeer has never been a problem with my car. And I don't run a rear bar and I don't know too many z-cars that run one. If you can get katman to speak up you'd get the benefit of a multitude of years of experience. He needs to write a book.

Tom
ITS #54 240z

[kthomas]

To expand on my zcar.com answer, your toe settings were about right, your camber setting were about right depending on the tires (might need more front if Hoosiers), whatcha running?

Understeer when, at turn in? After power application? Mid corner? Slow turns or fast turns? If you have enough bump and rebound then my earlier suggestion on the other forum should work (try 50# more rear spring or 50# less front, depending on how abrasive the ride is at your tracks, and back off to a 1 inch front bar). I usually want to see corner weights, tire temps, and ride heights before I correct a setup, but with 350/250 and that big front bar I think it's safe to say you got too much front bias for a 240Z. Also, as was mentioned on the other forum, a softer setup will get you up to speed sooner. I usually start a rookie out in the sub 300#/in spring neighborhood for a season, but since you have some racing experience already might not be necessary. Keep us posted.

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katman

[kirkm27]

Thanks Katman. I am going to decrease the front rates to 300 and try that. My push was on entry and in mid-corner. The exit was already ruined by then.

My car was set up 50.5 front weight, 49.5 rear, 48.6 right, and 51.4 left. I have the corner weights written down, but I don't have them with me.