Clutch No Longer Releasing

[ianepperson]

Hi everyone! I created an account to see if I can get some advice on an issue I'm having.

The truck is a 1970 Chevy C/20, originally with an HD clutch (among other factory upgrades - my dad (RIP) had ordered it from the factory with a bunch of additions). 1st gear is a granny gear. The engine has been replaced and my mom tells me that she had someone "replace the clutch" just a few years ago.

I borrowed the truck for a desert camping trip, and it ran like a top for a few hundred miles up and back, then 5 miles from home it won't go into gear. It's as if pushing in the clutch pedal does nothing - 1st gear grinds (non-syncro) and no other gear will slide in. I managed to hot-shift for the last few miles and started looking at it. There was no pop or breaking sound, and there's no additional noise coming from the housing.

I read that the linkage sometimes gets badly worn. I had about 1/2 of thread to tighten it up and noticed that the arm protruding from the bell housing has two positions to land the linkage, and it was on the outer (easier pedal, less travel?). I moved it to the inner (slightly harder pedal, more travel) and tightened up the push-rod to snug it up, but it didn't seem to make any difference.

I pulled the lower inspection plate to look at the pressure plate today. Everything looks OK, but I'm not familiar with this setup. I did notice that when I had my son press the clutch the flywheel moved forward about 1/16" - is that normal? I was able to pull it back by hand. I reached up and felt the throwout bearing - it seemed correct and I was able to spin it with my fingertips. It did feel as if there was more space than I imagined - perhaps the pressure plate is missing a finger? I didn't want to miss my own fingers so didn't feel it as my son pressed the pedal. I did see the pressure plate slightly move off the clutch plate, but perhaps not enough?

Any advice would be greatly appreciated. Thanks!