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-   -   Multi-Purpose FB (https://www.rx7club.com/race-car-tech-103/multi-purpose-fb-499409/)

8-ball 01-14-06 07:58 AM

Multi-Purpose FB
 
May be impossible but, I would like to build an all around car (Auto-X, Drag, Track Day Car etc). The plans so for (none implemented) Ford 8.8 rear, FC Sub Frame (front) small block chevy (350/383???) and Turbo 350 tranny. My question is, What spring rate to use front/back and what shock/strut package to use?
I know that compromises will have to be made. Thanks for constructive advice, no flames.

mikey D 01-19-06 02:52 PM

why do you want to go with a v8 is my first question.

Do you realize how little power it takes to make an FB into a 12second car.

autopaul 01-19-06 03:16 PM

im having the same problems.. other than the fact that i will be using a rotary powerplant,, is what coilovers to use... i have looking in the suspension forum, and coilovers are definatlely the way to go, but it may require custom valving. and springrates.

i don't believe anyone here is running fc subframe with coilovers yet (fc coilovers that is). unless they are keeping quiet i would love to hear from them as to what has worked, and what is too stiff etc.. the problem is that if the springrates that are coming with the fc coilovers are meant for an fc, then it may be too tight for an fb, causeing a rough ride and unusual traction problems...

for your case i would suggest that with the fc coilovers in the front and the added wieght of a v8 you could get away with it,, as for the back being solid axle,, using adapted fc coilovers with custom mouts would probably also work, but as i say it would probably be very stiff. (especially since your using it on a solid axle with the coilover mounts located behind the axle.. ) having the springs located behind the rear axle will cause the actual wheel spring rates to be much higher than the coilover is rated.

throughout this year i should have my car on the road with some sort of coilover setup figured out.. but untill then its research and lots of work.. looks like youve got allot of work ahead of you,,

Paul

wrxracer55 01-19-06 03:34 PM

I'm currently building a car with a ford 302/T5 tranny. The 5.0 ford is lighter than the chevy, and that is why I chose it. I'll be running 400 lb front and 200 lb rear spring.

I chose the 302 because the whole engine was cheaper than one rotor housing for my 12a, and will easily run 11s with a road race suspension in it.

autopaul 01-19-06 04:55 PM

does anyone know what a 2200lb fb should be running for springrates.. (fc front subframe. 3rd link, and panhard bar,, i can get away witha bit higher in the rear with 3rd link right?

i just dont wanna slide all over the road with fc suspension thats oversprung for my application,, i was told that the lowest sprig rate i could with a revalve on the coilovers is, 391 on the front, and 279.5 on the rear... is that appropriot for my setup,., i want stiff bud i dont want crap.

thanks guys,, sorry if im stealing your thread. might help clear up some issues for people running fc front subframe though..

Paul

autopaul 01-19-06 05:07 PM

for the record im building an all round car too,, may even serve some daily driving, but we'll see how that goes,, anyway its gonna be drag, drift, autox, and maybe dd on occasion,,

im big into wieght reduction so i wont be doing a v8swap any time soon, (not to start a war here,) ha,

but as for suspension ive been doing allot of research on coilovers.. and it seems to be the best bet,,,

look at it this way, (for fc subframe guys)

tokicos or kyb or replacement other shocks run from 350-500 for a set,
now you have to get springs.. (unless you want stock springrates.) and thats about another 150-400 depending on what you do.. so now your at about 700 (est.) and then you want to slam it, and you need camber plates.. anywhere from 150-250,,

so by this time your like.. i like my setup but i kinda wish i could adjust it (ride hieght and dampening) and youve almost spent about 1000 anyways,, (which is about what cheaper coilovers go for..

it all depends though,, some people will be happy with the shock/lowering spring setup, and others go for the coilovers,,

once i get coilovers there will be a writeup available on "how to" put fc coilovers on the back of your fb live axle.. (although it will be specific to my setup... )



Paul

8-ball 01-20-06 12:21 PM

To answer the first question, I already have the V8. I got the idea of the fc subframe in an
FB from Omid (?) on BCRX7.com. He has a detailed write up on it. This car will not see the street. Thanks for your input.

autopaul 01-20-06 05:49 PM

if i were you,, i would use fc coilovers aswell,, if youve done a v8 swap you should have the fabrication skillls to make the coilovers work in the rear,, or find somewhere you can order just the fronts, and then order just the rears and some lowering springs for the rear,, i think just about any springrate meant for the front of an fc would work welll for an rx7 with a v8. just cause of the added wieght..

on the back i would do what everyone else is doing,, and run 200#,, and maybe a beefed up third link setup for your axle..

8-ball 01-20-06 07:13 PM

Good info, keep us posted on the coilover setup. Good to see someone else wanting to be
able to use his car for different events. Build it to have fun!!!!!!


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