I have me an '84 M491 coupe with a 3.6. It was a race car when I bought it. The roads I drive on can be awful. Sometimes I find myself
avoiding driving the car unless the roads will be smooth. That's no good. I'd like to adapt the car to the drive, but I'm not sure where else I can go. I have an '87 coupe that is bone stock. The ride is far superior in the comfort department, and it's serving as my baseline. If I could get my '84 to behave like my '87 (possibly even smoother), I would be happy.
The car is ~2500 pounds and rides on 17" wheels with tire pressure around 28-32psi. I don't want to go to 16" wheels, because tire selection is slim for wheels this wide (9/11), though I might could go smaller in width for the sake of tires...meh. I've gone from 17" to 16" on another car and the change was not dramatic in changing the ride quality compared to a change in springs/shocks. If my E46 M3 could ride smooth on 19s, I suspect this car can with 17s.
I got the car with (I think) 23mm torsion bars in the front and 33mm torsion bars in the rear, with a set of shocks to match. It currently wears a set of stock 930 shocks and bars (18.4/26) that I bought from a Pelicaner. This change was significant, but it didn't go far enough. Thing is...I don't think there are softer springs for these cars, so I don't know if I could go softer here even if I wanted to. I plan to add maybe 100 pounds to the car (front bumper, sound deadening), but I don't expect that to have a tremendous effect on the suspension.
It wears Smart Racing sway bars front and rear, and they are quite thick. I would suspect that these are the culprit, but train tracks and ruts that affect both wheels equally are just as jarring as single-wheel impacts, so I believe the situation would still exist if I had
no sway bars.
The car is lower than stock, but I don't believe ride height effects ride quality until something hits a bump stop. Here is how it currently sits:
I plan to replace my rear spring plate bushings this winter, and while I didn't plan on changing anything else while I was in there...well, now I'm wondering if maybe I should...So...This thread. Would softer bushings up front have a profound effect or is it marginal? My guess is that the ones that are there are as hard as they come.
Is there a more scientific way I can go about determining what is the primary contributor to my harsh ride?