Clutch chatter in reverse only
 

I have clutch chatter only in reverse. Transmission is an M-20. Rear end is a stock 3.55 Safe-T-track. Engagement is smooth in the forward speeds. No chatter. Transmission was recently overhauled by a competent transmission shop. The clutch is new and is adjusted properly. I should also point out that I had chatter, in reverse only, before the transmission was overhauled, and, clutch replaced. Any ideas as to what could be causing the chatter only in reverse? Any help appreciated.
Thank You.

I have exactly the same problem with my '64 with M20, 3.23 rearend, 10.5" diaphragm clutch. One difference, however, is that mine only chatters when hot. When first started in the morning, there is no chatter.

Also looking for help.

Subscribed. What causes chatter, anyway? I get it intermittently. More even car is hot I think. My clutch is about 4 years and 3,000 miles old.

On my 66, 389, 3x2 m20 with 355 posi, it doesn't want to shift into reverse when hot but does it with the mild grinding of gears. (not clutch chatter). All works fine when cold or at operating temperatuer. I'm 99% certain that I need to make a turn or two on the clutch adjusting rod, but have been too lazy to go under there to do it.

For the car that has trouble going into reverse when hot, try this little test. Shut the engine off and try to shift it into reverse or with the engine still running, put it in 1st and then quickly into reverse. If it goes in without much issue in these conditions but not when running and going from neutral to reverse, the problem is a grabbing pilot bearing. Since reverse is not synchronized, the input shaft is still turning when you clutch it instead of stopping and this causes the grind or no shift to reverse.
For the chatter in reverse only, I will have to think about that one for a while.

just a thought. but when reversing. the engine is twisting the opposite way. this along with light clutching the linkage to clutch is mounted to the frame and engine block. could the action move the clutch rods in and out to cause eradicate engagement.

Check for worn/sagging engine/trans mounts. Also check for worn bushing in the rear axle assembly.