Loud Clunk/Bang

[Duffman]

I had my 4 speed tranny and R180 diff replaced last year with an 83 5 speed and R200 diff. Love the upgrade!! I have had seals/gaskets replaced on both recently, as well as all bushings, springs and struts underneath. Problem: was in a parking lot, went over a speed bump, foot accidently slipped off the clutch (popped the clutch), and, as the tires squealed slightly, I heard a loud clunk/bang in the tranny tunnel. It seemed to be right next to me. I know the ujoints are fine, the mounts for the tranny and diff are new and were just checked. Could it have anything to do with the replacement tranny and diff? Can't see anything visibly. I have duplicated this problem again, under similar circumstances of quick acceleration. It is the only time it makes the noise, never when I am already moving.

Any thoughts?

Thanks!

[five&dime]

Check out this thread.

http://www.classiczcars.com/forums/showthread.php?t=31777

I know you said you checked your mounts, but how thorough was the diagnostic? This part may be your problem. It's a quote from my dad regarding his clunk.

I also recall a retainer strap in the trans tunnel that holds the driveshaft or the diff in place. Could it be a failing strap or maybe it's just loose? I would imagine if so, it could cause some contact under extreme torque.

"Zedyone.......I think you may be going in the wrong direction with your diff replacement. Check out what Yellow Jedi said....It wasn't his u-joints or diff mount...he replaced those twice....when he finally replaced all rear bushings the clunk disappeared! My guess is his problem was the four rear control arm bushings...remember the u-joints, driveshaft and diff mount aren't the only areas under stress in the rear. The wheels and tires are trying to twist the control arms apart! If the four large bushings aren't installed correctly or have been worn from high torque runs over the years, you can have metal to metal contact or severe movement on either side of the bushings. However like previosly mentioned in this thread, they must be installed properly. Loosen the large bolts on the forward and rearward side of the bushings then take the caps off (2 small bolts on rearward cap, diff bracket capping forward bushings) When finishing the job, tighten the large 4 bolts only when rear wheels are under weight of the car. Clunk elimination is part of Z ownership.....good luck!"

Edited January 28, 2009 by five&dime