John Stimson wrote:How is that functionally different from an adjustable-length control arm?
John, a typical A-arm operates as a plane defined by the typical three points - the two inner/chassis-side pivot points, and the center of the ball joint.
The knuckle sits some vertical distance "above" the ball joint's axis of rotation. The SPAC's clarification shows how it is legal, in the case where you've replaced your control arm through the camber kit allowance, to have a ball joint where the vertical distance the spindle sits above the ball joint's point of rotation, is nonstandard. This is analogous to a change in spindle/knuckle height, as opposed to an arm length change.
Here's an illustration of the parts and what they can do to a camber curve:
http://www.pozziracing.com/power_perfor ... torspo.htm" onclick="window.open(this.href);return false;
While I wasn't on the SPAC, my hunch is their interpretation of the allowance was that a person was supposed to be able to buy an off-the-shelf aftermarket control arm, and have it be legal (assuming it met the bushing restrictions). How would you know for sure if your aftermarket high-performance control arm had the same height as Stock? The answer is, that the allowance doesn't make any sense unless you allow for this variation.
I think the STAC, in their Fisher-Price approach (can't talk too much crap since I'm on it again), got scared that people would feel obligated to engineer stuff to get the most out the allowance, which they want to avoid. The problem is, you can't be sure any complete aftermarket control arm out there will be legal on your car unless you can somehow adapt your stock ball joint to it. Fortunately with the Camaro I was able to do exactly that, others may not be so lucky.
Pros and cons to each approach, I can see why each committee went the way it did.
