M20 poping out of gear?

[wtexz10]

I have a question about my M20 transmission in my 69.  While cruising on the highway at 70, and I rapidly let of the gas, the trans pops out of 4th and into neutral.  No problem at all shifting throught the gears up or down.

If I keep my hand on the shifter it won't pop out.

Could this be a linkage adjustment proplem?

Thanks,

Kris

[Stingr69]

You can try adjusting the shifter but I would be looking for a worn 3-4 slider (part of the synchronizer assembly). The tiny clutch teeth on the perimeter of the gear fit inside the slider grooves and will get worn open after many miles. This can cause the tranny to pop out of gear when you get on and off the gas. It might be something else in the front bearing or input gear/mainshaft rollers but either way it is time to overhaul the tranny and replace the worn parts.

-Mark.