Sounds like something is off center. Have you ever replaced the throw out bearing arm and bushings? The chattering may be the throwout bearing not lining up on the same rotating axis of the pressure plate. This will chatter because of the "sliding" between the mating surfaces. What does the face of the throwout bearing look like?

We replaced the arm and bearing a few months ago, however, after we ran the engine without the flywheel seal, the throwout bearing wasn't spinning as freely as it should and grinding a little. Kostya got a new throwout bearing from Kermit yesterday and we plan to put it in sometime this week. Hopefully that will do the trick.

I hope that fixes it, I know it's been a real pain in the........

posterior.

When you replaced the arm did ya replace the bushings too?

We didn't replace the arm, but we replaced the throwout bearing with a German Sachs one. I bought a new bushing set, but it wouldn't work. I think it's a kit for the newer model transmissions. The shaft feels fine though, not much play at all.

Is the throw out bearing upside down?

I don't think the throw-out bearing can be upside down.

Well, we got the motor back in it and on the ground. So far so good , finally. Doesn't chatter at all and shifts smoothly. Hopefully it stays this way!

Hey man Im glad your up and running again..