400 or 450 rear springs?
 

I have some 700lb springs on the way for the front of my car. I wanted to get some insight on the differences of 400/450 in the rear. The XIDA recommended rates are 700/400 and 800/500 with aero. My local track is fairly bump and I do drive the car a bit on the street so I figured a 700/450lb set up would be a good medium? No aero yet but I'm currently working on a splitter and when I get some cash together I will be picking up an APR 200.

This is on shocks revalved by Bernie for 700/400 but you can go up/down 50lbs either way so a 450lb spring is still fine for the rear valving.

700/400 here and loving it. PM johnwag or tehjeffman and see what they say about 700/450.

will do, thanks..

are you running any aero parts?

Uh 700/450 _with_ a splitter but _no_ wing will make the car more tail happy. I run 500/300 right now and will probably bump to 700/400 with no aero yet.

If you run only a splitter, you would go softer in the rear to gain grip there.

I think you misunderstood or I wasn't clear. I don't plan to run just a splitter. I would run it in conjunction with a rear wing.

Stick with the known 700/400 unless you've got a good reason to change that.

I think I might have gone to 700/450 from my 700/400 just to run with a little less rear bar but I made the swap to 800/500 instead.

If you plug the numbers into FatCats spread sheet 700/450 is closer to 800/500 in terms of role stiffness balance.

Bob