Sitting at the stop light, especially on a slight incline, the transmission will often jump out off gear when I try to take off. What causes this. 1974 Side-Shifter.

The synchro ring is worn and/or the 1st/Rev slider is worn. One rides on the other. When the components wear out... they wont "stick together" when you put it into gear. Typically you see this on 4th or 5th gears..

I'm betting it jumps out of gear any time you unload the torque (off and on the gas while in gear)



B

On das Ghia, I had a similar problem, with 3rd gear.

The suspected cause:
I installed an aftermarket Shift Lock - which interfered with the geometry of the shift lever just enough, that I guess it wasn't fully engaging in third, and started to slip out every now and then.

If it's a worn synchro - I think it'll happen under load more often than just driving around.