I recently installed a new Tremec 5 speed in my 67 Camaro. In the process I had the flywheel resurfaced. I also installed a new Borg Warner pressure plate/disc, new throwout bearing, pilot bushing, both engine mounts and transmission mount. The bearing retainer on the tranny is brand new of course, I inspected the clutch fork and lubed the clutch fork ball. I have adjusted the free play a couple times. I have gone back and checked the crossmember and mounts for tightness. It chatters pretty bad while engaging the clutch in 1st gear. Reverse is even worse. Did I miss something?
By the way, the engine and trans mounts were not of the highest quality. I bought them at a local chain store. They were only 5 bucks apiece.
Hmmm, I put a Muncie in mine last winter, and initially had problems both with chattering and the clutch not disengaging all the way. Per DavidPozzi's advice, I put some miles on it, and sure 'nough, after about 500 miles it loosened right up. Now, after 2500 miles, it's as perfect as could be.