I have a car with a 60 hp flathead, in first an second gear it is smooth. when backing up it vibrates an shakes bad. what could be wrong. Thanks for your help.
Mine used to do that also. Clutch chatter. I realized I was slipping the clutch more in reverse than first gear to control my speed while backing up. Now I just let it fully out like I do when going forward and all is OK. No more clutch chatter. It may work for you.