Heres the deal. I just had a set of FK coilovers installed on my e36. A few days after driving I took it back to the shop that did the install because of rear clunking going on. They searched for 3 days looking, replacing bushings to rear brake pads to find the noise. They called me and saying it was the actual coil spring alone making the noise. My first thought was to have them take out the rear spring perch, as ive heard that the movement of the spring in the perch can clunk. The other thing I heard was "coil silencers" that wrap around the coils to prevent coil bind. Any help is much appreciated!