Hi Guys,

What are the average spring rates you guys are using front and rear. How about spring lengths? We purchased a set of AD shocks from a guy the quit on his Prod project. Emailed Ground Control with the numbers to get an idea of valving.
Where should we start?

Thanks Eric

 

front rate is usually 350-450lbs in 6-7" spring

rear is 225-250-275lbs in 6-8" spring

length depends on how low you want to be. with YOUR camber plate/spring perch/coil over combo, they vary a bit.

for example one of our cars is at a 25" ride height (top of wheel arch to ground) with a 6" front and 7" rear springs that's about as high as it goes. which is fine cause its mostly a street car. with 7" springs 24ish would mean its all the way down...

if AD = advanced design, you should at least make sure they actually work before you put them in

 

I saw your other post on another forum and a 400/250 starting point, also I believe about what Mazda comp did/used to recommend. While the reply came from a very respected and good driver, those aren't going to be his spring rates nor would he disclose what he's dialed in. Call Flatout http://www.flatout-motorsports.com/index.php who has campaigned many winning ITS cars, they were recommending a 550/400 last I heard.

 

Thanks! From my digging it sounds like 7" and 10" springs. Any opinions there?

 

I was running a 7" 400/300 setup on GCs and Konis. With the collars nearly all the way up it was just a tiny bit low (the front just tucks and the rear rubs occasionally), but doable on the street and with my r comps for auto-x. I just installed a set of 6" 650/500 springs, and which sit at nearly the same ride height as the above setup. These things are pretty damn rough on the street, and I can post a auto-x report after Sunday. Also, helper springs in the back could be useful, I have to check to make sure they seat right every time I change tires. Again, your setup may vary, but I'd probably err on the taller side.

 

FYI- This for an ITS/ PT car. It won't see the street except for loading on the trailer. Thanks for the info guys

 

this is an article from grassroots motorsports magazine about Sylvain Tremblay's ITS FC RX-7 that won the SCCA national championship 2 years in a row, and it lists the spring rates and other details on how he set up the car to win.

http://grassrootsmotorsports.com/articles/lucky-7/