FD3S Spring Rates for Autox

Mazda RX7 and RX8 Suspension, Intakes, Headers, Exhaust, Shocks, Springs, Sway Bars, Brake Kits, Autocross and track mods.

FD3S Spring Rates for Autox

Postby cosmo105 » Thu Jan 21, 2010 6:30 pm

Hi Brian,

I'm kinda new to Autoxing (drag racing background) but I'd like to know what is your experience with spring rates for a "kinda" DD FD Autox car.

Just a little background:

I have a 93 FD that has been modified with a single turbo T04e with all the applicable mods (injectors, PowerFC, FMIC, 3" all the way back, HKS ignition, all the reliability mods) to put down 400rwhp at 15lbs. Suspension mods currently are RB front sway, Tanabe rear sway, Eibach springs and Tokico Illuminas. I borrowed a set of old Victos (245/45/16) and could hold her own in the SM2 group if the track was configured to "let her legs stretch".

This year I'm planning to put coilovers on with a set of Enkei rpf1's with Kumho V710 285/30/18's all around. But with limited resources, I have a budget of less than 2k to purchase coilovers. In that range, several coilover manufactures have a standard 10k/8kg spring rate but some have a 12k/12k rate.

My question is what do you recommend for an FD that sees about 3k miles per year that can be competitive at Autox at the local level?

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Postby Brian » Thu Jan 21, 2010 9:13 pm

Sounds like a beautiful FD. For track I like that 12/12 combo but not for autocross. That 10/8 is okay but my preference would be something like 12/10...or even better 12/9 for autocross. You have a LOT of power and most autocross courses are tighter than your car likes and this greater spread in rates would help you get the power down just a little earlier out of the corners and should give you a faster overall result. I know that is not one of the choices you listed but you might talk to one of the 12/12 coilover makers you are considering...usually a minor fee to change spring rates before they ship. I don't think 12k front is too stiff for daily on a car doing just 3k per year.
Brian Goodwin
Good-Win Racing
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Postby cosmo105 » Fri Jan 22, 2010 9:53 am

Thanks for the quick response Brian. I'll be calling you before April to purchase a set of the Enkei's!
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