I have A'pex N1 coilovers and they come w/ F/R 9kg/5kg. It feels great for the street and aggressive driving, but I plan on swapping them over to a hatch that will be mostly for track use. So, I'm thinking about keeping one of the springs and changing the other. Which of these would be a better combo:

Front/Rear:
5kg/7kg (keep 5kg rear spring and move it to front & buy 7kg rear spring)
7kg/9kg (keep 9kg front spring and move it to rear & buy 7kg front spring)
9kg/11kg (keep 9kg front spring in front & buy 11kg rear spring)

Would the 9/11 setup be too ruf as the car will still see some occasional street use? For reference, here's what the rates equal in lbs/in:

5kg/mm = 280lbs/in
7 = 392
9 = 504
11 = 616

Oh, and the front and rear springs are the same length, 225mm (~9").
Thanks.

 

anyone?...any suggestions? does anyone track their car?...if so, you're help is greatly appreciated!

 

Search for some of Prospecs treads.....(Roger Foo) he says in one of those what spring rates he uses....