I'm still trying to chase down my
suspension bug (why the right rear sits higher than the left rear). Here is Maximum Motorsports' advise to me:
I would jack the car up, loosen both locknuts at the end of the PHB rod. Remember, the one with notches machined on the OD is a left hand thread nut. Back both nuts off several turns. Put the car on level ground. Spin the PHB rod by hand CW then CCW, until you find the place where it turns the easiest. This is the point at which the rod’s length is correctly set to match the geometry of the rear
suspension. Jack the car up and torque the locknuts. These will eliminate any possibility of the PHB jacking one side of the car up. It can do this, but only if there is a lot of preload on it.
For any of the
control arms which have rubber bushings installed in them, you do need to make sure that the bolts were tightened when the
suspension was at ride height. You can do this in the rear by putting jack stands under the rear axle. The FCA bolts need to be down with the car on a drive on lift. If you tighten these bolts with the
suspension not at ride height, the rubber bushings will either raise or lower the ride height at that corner of the car as they are torsional springs.
For the rear springs, the end of the coils should point to the left. This is the same things as saying that the end of the coils should be located in the 6 o’clock position when viewed from the top.
To reduce the ride height, you could try clocking the rear springs to the 9 o’clock position. Do not try to cut the rear springs. If you do this, they will no longer fit properly. You can clock the springs differently from side to side.
When you pull the springs out to compare them, remove all isolators, put the springs with the ground end (top) down and set them side by side so that the open end (bottom) of the springs are nearest to each other. That will make it easy to very accurately compare their free lengths.
When you put the springs back in the car, I would swap them from side to side.
On one car, I have seen the box which is above the rear upper spring perch was collapsed. This caused the ride height on one side to be reduced. If this is happening on your car, it would be the LR upper spring perch.