RECENTLY I REBUILT MY M-21 TRANS. AND REPLACED THE CLUTCH, I ALSO REPLACED THE PILOT BUSHING AND THE THROW OUT BEARING. MY PROBLEM IS THAT I GET AN INTERMITTENT GROWL FROM THE TRANS. AREA, I HAVE NOT MOVED THE CAR HARDLY AT ALL SINCE THIS IS HAPPENING. I HAVE BEEN TOLD THAT I COULD HAVE A BAD THROW-OUT BEARING OR THAT THE IMPUT SHAFT IS NOT PROPERLY SHIMMED. IT DOES SEEM TO QUIET DOWN WHEN I ENGAGE AND DISENGAGE THE CLUTCH PEDAL AND IT IS NOT CONSISTENT WITH HAVING THE CLUTCH FULLY ENGAGED OR DISENGAGED. ANY IDEAS WOULD BE VERY HELPFULL. THANKS SHELDON
Did you put a brass type pilot bushing in? If so, this could be the problem. Best solution would be to remove it, and install a roller bearing type replacement bushing. These are 100 times better than the bushing.
Can't say for sure, but it's not unusual for the Muncies to have some end play in the cluster and main shaft gears. This will give you some noise when idling under no load. Trans is full of 90 wt oil, right? Worn bearings will cause noise also, especially in reverse, but the rebuild should have taken care of that. I'd say drive the car and see how it works. tom