TKO 600 Grinding.

[Excaliber]

Jim, do you know if your running a bronze pilot bushing? That and/or the clutch plate not fully releasing is what this boils down to. Something is causing drag on the input shaft of the trans. I suspect a bearing would tolerate misalignment of the bell housing more than a bushing would.

What other causes might come into play when the clutch disc does not always fully disengage? Warped disc? Insuffcient tavel with the master cylinder? Possible air bubble in the master/slave cylinders not allowing for enough travel of the throw out bearing? Not getting a full stroke on the master cylinder because of occasional internal leakage of the hydraulic pressure from the master or slave at times? I wonder if slowly vs fast engagement of the clutch pedal may be a factor in regards to internal leaking of hydraulic pressure? Pumping the clutch pedal is a good diagnostic procedure, assuming enough "time" is given to allow the gears to stop following said pumping action. Slight misalignment of the bell housing causing the pilot bushing to "rub" sideways on the input shaft? I would rule out the pressure plate (cover plate) itself, mostly because I can't think of a way the levers and springs would fail to release consistently. How about the throw out bearing release arm "pivoting" or moving at an angle at certain times and thus not giving full travel to the throw out bearing?

As has been noted, correct clutch adjustment, which allows for a FULL stroke of the slave cylinder is step #1. If full stroke only allows for a minimum of pressure plate disengagement that would certainly be a problem. "Almost releasing" would account for sometimes it grinds and sometimes it doesn't. A full stroke must be verified.

Looking for repairs to the trans itself is a red herring (related, but misleading, not the real cause), I do believe. The simple fact is this could (and has) happened to top loaders, T5's, GM trans, any manual trans on the market. In that regard there is nothing special about a TKO.