ok, so i have the Fc front subframe swap done, and im looking into buying aftermarket coilovers (kyb suspension and edelbrock adj. coilover springs, so now that im buying these parts i was wondering wouldnt it just be easier to buy the complete fc set for front and back of both,
and i know what your going to say about the rear coilovers, its for a irs car, and this is solid axle yes im aware, but i know i can fabricate a different mounting point for it if need be, my question is more about spring rates and whether the fc springs would be too stiff for a fb,
i have a welded in roll cage aswell that runs right beside the top of the suspension mounts so i dont have to worry about a strong upper mounting point

any tips or comments welcome,
i am seriosely considereing this
if its any consellation im planning on doing a tri link, and panhard bar setup at the same time as the rear suspension... if that makes a difference

 

Go for it!

As I recall, FC's mount the spring/shock close to the hub area so their spring rate is very close to actual wheel rate (no wonky leverage issues).

FWIW I'm running 200lb springs on the rear of my car, still with the Watts. Handles just fine, a little pushy on corner entrance if you're not diving in. But then my ride height's a bit different, and I've got no swaybars either...

 

So, I'm trying to understand exactly what you are trying to accomplish. You think it would be easier to buy a full FC (pre-determined by some dude over at "XYZ" company for the FC) spring set so that the spring rates match front to rear? You will then have to modify the rear end to accept these springs that really give you no benefit other than they are supposedly matched to the front?

You can get any spring rate you need that will fit with no modifcation on the rear. As an example www.gforceengineering.net sells "Red Dot" rear springs available in just about any rate you could want.

To determine the proper spring rates you would need to do a lot of mearuring and math...or you could just guess. On a modified car that borrows parts from other cars it really isn't valid to just use what someone else suggests for one car or the other. It may just work out that the spring rate for either are very close but it is really just a coincidence.

From my knowledge the front FC suspension isn't whole lot different than the SA/FB geometry wise, correct me if I'm wrong. With that in mind I would just treat the car as an regular FB to determine spring rates.

What is the the car going to be used for?

I do not reccomend buying the FC springs under the impression that it would be easier. If it requires modification (quite extensive actually), it can't be easier if you can get the exact same thing (or at least the same spring rate) that will work with no modification.

just my $.02