TKO 600 Grinding.

[jhv48]

Ed, the clutch was our first thought.

Insulated the clutch lines from heat.
Replaced slave cylinder just in case.
Changed fluid to high temp fluid.
Measured and checked over and over. Not dragging at all when hot or cold. Disengages completely about 1 1/2 inches from the floor.

Elmariachi, I hope they miked both the end of the input shaft and the inside of the bearing. Not sure, as the trans is already back in the car. Neither the bearing or the shaft show any signs of abnormal wear, yet, when the bearing is replaced, the trans shifts like new for about 1500 miles. Then the old problems return. Something is not lining up properly and causing the input shaft to drag slightly after a period of time.

We're all stumped! All parts, from the crank to the trans have been measured and dialed in and all are within manufacturers specs. We replaced the bell housing just for insurance. Don't want to do this a fourth time.

[jhv48]

So far, no problems. Shifts like it did when new.

We didn't find a smoking gun, so if it happens again, we're lost.

Like I said before, there was some dried grease on the pilot bushing when we pulled it out. It was lubricated on installation by a thin film of motor oil. This dried grease could be just enough to cause the input shaft to drag just enough to keep it spinning when the clutch was disengaged.

This time, we used a light application of high temp wheel bearing grease (Tremec told us to use it) on the inside of the pilot bushing. So, if the problem doesn't reappear, then that was the culprit, though I can't figure out why engine oil would dry out like that. Is the end of the crank and the spinning input shaft any hotter than a moving piston? But then, that oil is circulating isn't it? The new bell housing was .001 better than the one we originally had (.0025 versus .0035) but both are in spec.

Will let you know in about 1500 miles. If it happens again, I'm going to drive it till something seizes or disintegrates.