The HREs have plenty of extra room, the stock calipers are actually huge and I still a have plenty of room. That was one of my concerns as when Spires told me to go the Alcon direction

 

Max

Was looking for your 1/4 results here. Guess, you did not have a chance to take it out to test it?

Monday, I'm finally hoping to get my XKR on the jackstands to install wheel spacers, paint the calipers etc. That will be a good time to check on the suspension, calculate some suspension values after measuring the components (roll bars, springs) and their locations. Will post the results.

 

Looking forward to hearing how this works out for you. If we can correct rear camber then lowering becomes a whole lot more justifiable.

 

I think I can speak for Max but, the recommended shimming of the sway bar has nothing to do with correcting the camber.

SoCalBabe had some custom shims made to correct the camber and it was not a cheap or easy process, according to her post.

Running 2+ cambers should definitely increase the wear on the inside tire edges. Roughly figure with a 10" wide tire thread (285/30 tire), every degree of camber will make the tire's outer edge tilt about 0.175" higher. So, if you have 2.2 degree camber, like Max's car the outer tire edge is 0.35" higher and, in the case of SoCalBabe's 3 degree camber the tilt is 0.525". Such differences may not effect cornering performance as much as it will effect tire wear. If a symmetrical tire was used they could be switched between the sides to even out wear. Many performance tires, however, are uni-dircectional.

I should have some calculated numbers by Tuesday on spring and sway bar rates as well as wheel rates for both springs and swaybars.

 

The shimming has to do with getting some preload on the sway bar to help with turn in.

Albert - thank you for working out some spring rates, as I'm eager to try them out if they are within range of the dampers.

After my last track day I'd actually like -2 degrees of camber in the rears and around -1.8 in the front. I may also go for a little toe out on the front as the low speed turn in still exhibited a bit of push. Of course I could go into the corner slower, but the slow corner entry is where the XKR suffers. Long fast sweepers, mid corner transition and corner exit are spot on. I was keeping up with a modded GTR all over the course except the slow corners. He killed me there and I probably ended up over driving the car in those turns. A few full race Corvettes were having issues in these corners as well, and I remember my Corvette did not like slow sharp corners either. Its probably the fact of the weight over the front wheels causing the low speed push.

 

Yes, I can see why you would like 2 degrees camber on the track. The trick is to come up with a compromise that is good for both applications.

It was always an elusive attempt to set up a car to handle both slow and high speed corners. Basically in racing, we tended to setup the car for the high speed corners and suffered with, at times, pig-like understeer in lower speed corners. Even in F1 they have serious issues with understeer in tight corners. My formula car understeered something terrible in slow corners.

Not sure if it is a "weight" issue as an F1 or my old mid-engined Lambo had the weight back over the rear wheels, yet, they still had slow corner understeer. It is just seem to be nearly impossible to have your cake and eat it too. I remember setting my autocross champ Mustang GT to super neutral to for those ultra-tight turns in autocross. Right after the competition I would quickly reset the suspension before heading home. One day I forgot to do that and it scared the pants off me taking some medium speed corners on the way home.

The nice thing about having so much torque as in the SC XKR that you can use that torque as a second-steering wheel, effectively reducing or cancelling understeer.

 

I haven't forgotten about this, just waiting on HRE to refinish my wheel.