Quote:
Originally Posted by mickmate
(28-25.6)/2=1.2" drop at stock control arm positions. That's pretty close to the 1-1/2" you're looking for. 28" is a big tire to start with, most of the 15's are around 26.5" dia. I haven't measured the SPF arms and put the data into CAD but they look good eyeballing them with the lower arms being pretty level at ride height and minimal camber change on an alignment machine. The rear uprights are fabricated parts and could be duplicated (or modified) with different height upper and lower brackets but you would want all your measurements off the car and a known good roll center height to draw and then build them to. That article tells why you shouldn't measure fender heights and then lists all the setting by fender height............??
|
My point with the tire diameter is that with the larger tires the car is higher in relation to the center of the wheel to get the required clearance. If you take a 28" tire off and put on a 25.6" tire the rear geometry does not change (control arm angles), but if you then start lowering the car because you do now have the tire clearance the geometry gets bad. Also measuring from the fender to the lower wheel lip works very well, but measuring from the fender to the ground does not.
The ride height chart is showing an optimum of 23.94" from the fender to the lower lip of an 18" wheel. I am trying to get to at least 22.5". The choice is raising the control arm attachment points on the car or modifying the IRS upright. My hope was that the upright may have been from a Mustang or another vehicle that someone had been making aftermarket parts for. For my fronts I was able to order Wilwood front spindles with a 2" drop.