I own a 2005 STi with coilovers, and I'm thinking about getting the whiteline front roll center kit for it. The common thought on optimal ride height is 14" front, 13.5" rear (center of hub to fender), which is what I'm currently at. The control arms are pretty much parallel to the ground at this height, and my ohlins DFVs have room to work. I can't really find much in the way of a rear roll center adjuster kit, so if I put on said kit, I have a few options, and I don't really know which is optimal. First, I could just lower the front enough to bring the bars back to parallel, and leave the rear alone. This would give me a bit of rake, but the front/rear roll center ratio would stay the same. The other option is to lower the rear as much as I lowered the front, keeping the car level. This would lower the rear roll center lower than the front, which as far as I can tell will make the back roll more which would have a similar effect as a smaller sway bar back there? Any input? Experience and height recommendations from whiteline would be very helpful.

My advice would be to add the adjusters and leave your ride height the same. The reasons being are that the STi front suspension is already travel challenged, and you'll want to be more in the meat of the negative camber curve rather than right on the edge. I would add caster through GC camber plates or an ALK if you haven't already. That made the biggest difference in front grip for my WRX on the track.

Well I should have a bit more travel on my Ohlins coilovers than stock (I seem to recall 5" total travel in front and 8" rear, with the front being about right in the middle of the travel at static ride height), but it's still not great. Right now I have the matching camber plates for my coilovers, which only allow camber adjustment. I was contemplating swapping the plates side to side and rotating them so that they point toward the transmission rather than each other. I would sacrifice a little bit of camber, but I would get a bit more caster out of them.

G’day everyone,

Iron giant, the roll axis (front to rear inclination of roll centres) is adversely affected on the STi by lowering as the front moves lower disproportionately to the rear and actually goes subterranean after around 1 ½”(?) down (roughly 340-350mm CWTG or centre of wheel to guard from memory). The 14” number seems comfortably within that but we used to run our tarmac rally STi ’05 at 330-335mm using Group 4’s.

That is, we designed the KCA313 ROCK kit to deliberately fix a perceived problem or issue with the front when lowering all round as we wanted to help restore the roll axis while digging out the front roll centre. The perception of parallel or level arms is a difficult one to quantify as the differences need to affect the roll centre calculation are minor and we also have the inclination of the strut (or virtual KPI) to factor in to this so it’s very difficult to estimate an RC outcome from perceived lower arm angle alone.

Can I suggest that anyone looking at this issue and wanting to learn more on the theory behind the tech take a look at this post  http://www.racedotcom.com/showthread.php?t=27475 . So in simple answer, our advice would be to change the ride height proportionately front and rear as a baseline and use the ROCK kit to fix the RC issue in the front.

Hope that helps

Cheers

Whiteline Jim

www.whiteline.com.au