1990 c-4 convertable w/ zf s6-40 tranny and 55K miles. Owned since new and I only beat on it very rarely.
When there is no load on the drive train and I feather the throttle, I get a single clunk as if I had a bad u-joint. When the car is at full opertrating temp, parked in nuetral, clutch in or out, I get continous non linear clunking. The sound appears to originate from the tranny but is diffucult to tell for sure. Most novices say I may have a bad throw out bearing. I removed the tranny and inspected all u-joints w no discrepencies noted. The clutch assembly (disk, press plate, TO bearing) appears fine less normal wear. The shop manual tells me to inspect the dual mass fly wheel but does not say what to look for to determine if it's good or bad. I can get a couple of degrees of rotation of the outer fly wheel which seems like normal dampening to me. When I grasp the tranny main drive gear (shaft) and quickly rotate back and fourth, I get a similar clunking in the tranny and it is obviousley not as loud as when operating, and seems as if it's normal gear lash noise. I purhased a new clutch kit, but I'd hate to put the whole thing back together only to find the same syptoms and I'd hate to have the tranny overhauled if it's not the problem. Any thoughts, comments or advice would be greatly appreciated. Thanks