Chrisman1969

Hi,

I am looking for some help picking the suspension for 306 Ford conversion GSL-SE, it will be used mostly for the track. My weight is 2600lbs w/o driver - 1440 Front, 1160 Rear, 350hp.

www.jickedoutbastards.com/rx7.html

I am thinking:

Ground Control Coilovers w/ Tokico Illuminas
G.C. Caster/Camer plates
1 1/8" Front sway
Eibach Springs

What spring rates should I use?
Any other constructive suggestions?

Thanks
Chris

OC_

This is going to be pretty hard to figure out. I can take a look through some of my books and see if i can get you a rate to start at. Then you will have to tweek the rate from there. I hear JC whitney has pretty good coil springs for dirt cheap, so if you need some springs for cheap, try them. I have a friend with a Fiat X1/9 that got some springs for his coilovers and the springs where very close in rate when he dynoed them.

I have 2 idea on how to solve this.

Plan A: would be to do it the right way, and find the linkage raitos on the springs. I have the formulas for many differnt types of suspensions in a book. You have a first gen, so im guessing strut front and solid rear. The solid rear should be ez.

Plan B would be to guesstimate: find how much the stock car weighed and stock rates and go from there...
example: if the front end is 2x heaver, get 2x heaver springs!......... this could work...

let me know if you still need help with this. If you do, ill consult my books on what to do, as im to lazy to get them right now, and i dont know if you got this solved or not.

Chrisman1969

Thanks for the reply.

I called Ground Control and bought coilovers and asked for their suggestions about spring rates. They gave me 375-400lbs springs for the front and stock stuff for the rear. I am pretty close to stock weight as I sit. I will get all of my stuff within the next week or two and will go from there.

I am really excited about this car. i hav autox'd it and I think with a little work I can get around the track quick.

Thanks for the reply.

Chris

OC_

well, if you cant get it 'right' let me know, ill try to help you out the best i can.

i did go fliping though a book, and it said that there is no leverage on a macpherson strut. But they do become less efficent when mounted at an angle (all strut cars have them mounted at an angle, and you make this angle greater when you put more camber in with a camber plate)
If i remember correctly, at a 45° angle, sping efficiency is down 50%
hope this helps out for spring calculations.