Ok, y’all, here is what I have learned about e30 suspension over the past 20 or so years.
EVERY CAR IS DIFFERENT....ONE SIZE DOES NOT FIT ALL!!!!!!
For cars to be equal, they must all be unwrecked (pinch welds in tact) with the same cage geometry, the same ride height same shocks and bars, and all the other requirments from SpecE30. Notice I left out springs. Even if the original test car had these specs, probably no other car in the series will since some will be pristeen, some wrecked, and almost all have a different cage. Therefore, spec springs do not work for every car! With the cage you have and the lack of stiffness of the chassis, you are basically tuning the chassis. What springs work with which chassis is, at best, trial and error. I found that a good base setup was 400 front and 600 rear springs. Of the cars I have built, some wanted 550 rears, and some wanted 650 rears given the same bars (BOTH OF WHICH NEED TO BE ADJUSTABLE). This allows the chassis to be tuned for most driver comfort and fun…and that is why we are here.
Some have complained the new setup to be too loose. If you could drop 50 pounds on rear springs and tighten the front bar you could (most likely) tune the looseness out and have a comfortable car.
One other thing: e30 ride height. There is one ride height that has the roll centers where the chassis wants them…period. The front, measured next to the pinch weld at the jack point at 5 1/2". The rear, measured next to the pinch weld at the jack point at 6". After the ride height is set, corner weighting can be done.