Seefo wrote:
Good to hear. Btw, I think we talked once a long time ago on miata.net. I remember asking you for the models on those seat mounts.
Oh, cool. Yeah, I remember that.
Seefo wrote:
Did you guys do any estimates on the spring stiffness after the cutting? What tire size are you guys running? 225 on a 16" wheel?
IIRC, the springs had 5 coils originally front and rear. We cut one coil off the fronts and about 3/4 of a coil off the rears. The OEM spring rates are something like 350 lb/in front, 180 lb/in rear. So, after cutting they would be something like 440 lb/in front, 210 lb/in rear.
The soft rears, the fact that we removed more weight from the back of the car than the front, similar camber all-around, zero toe out, and natural tendency for the car to understeer from the factory all point to a car that would understeer a lot. However, we left the rear ride height a little high and put as much weight in the back of the car as possible (battery, fire system, etc). The result: the car is actually very well balanced in the corners. Just a little bit of oversteer. If the rear were lowered any more and everything else stayed the same, we'd need to change something to get the balance back to where it should be.
Honestly, when we were doing the springs, I didn't really consider this stuff too much. I figured we'd try it out and cut another set of springs if we needed to make adjustments. This happened to work quite well though.
Right now, the biggest limitation on cornering is the shocks. OEM dampers just aren't cut out for lower, stiffer springs. ChumpCar just changed the rules about shocks. (Frankly, it probably puts this chassis at a disadvantage.) We'll probably run Tokico Blues in the future. I'm not going to be buying them any time soon though, since I just shelled out for some OE-replacement KYBs.
Tires are 225's as you said. Mounted on 16x8 wheels, with something like 38mm offset (don't remember for sure). The wheels BARELY clear the LS400 brakes. On the lexus/supra forums they generally say you can't get 16's to clear, but it's possible with the right wheels/spacers. We actually had issues at the test day with the wheel weights hitting the caliper due to the close clearance and had to move around the weights.
As far as tires go, if you want to be competitive and don't mind breaking the bank, you can run WAY wider tires. Problem is, they get WAY more expensive too. 225's are the widest available Rivals for 16" wheels at the moment.