TKO 600 Grinding.

[eschaider]

Originally Posted by jhv48

Update:

All parts are out and the bellhousing was checked and found to be within specs, .0035. The input shaft shows no abnormal wear. Some dried grease was apparent on the pilot bushing. Not sure where that came from. No seal leaks. Mechanic coated the inside of the bushing with some motor oil when he installed the second one. The dried grease could be what was causing the input shaft to drag.

Mechanic is checking the end of the crank for tolerance and then putting the thing back together with a new pilot bushing and new Quiktime bellhousing.

Will test and then report.

Jim,

The last item that could do this is incomplete clutch release where the clearance when the clutch is fully released is insufficient to fully release the disc. Usually the problem is nothing more than a little drag on the disc and can be fixed by depressing the clutch fingers or diaphragm a little more.

I think Ekrupa2 was on to this version of the problem fix when he was talking about the difference in clutch release when the car is driven in stop and go traffic. If your hydraulic line is close to the exhaust system it would be to your advantage to relocate it to a cooler position/location.

Additionally if the clutch is barely disengaging when the car is cold after everything in the can warms up you could loose just enough clearance from heat expansion to drag on the disc. Easy fix is to adjust your mechanical linkage under the dash to provide slightly more stroke on the clutch master cylinder for a little more release in the can. If you are using a push type slave cylinder make sure you have sufficient travel left to do this without pushing the piston out of the slave cylinder bore.

If you are at the limits of your slave cylinder piston travel then position its attachment point on the throwout arm closer to the pivot ball so it requires less arm movement for the same throwout bearing movement. You may have to do a little experimentation before you get it the way you want/need it.

When you position the slave cylinder push point closer to the pivot ball you will decrease its leverage and this will give you a slightly zestier clutch "pedal feel". A diaphragm clutch will have slightly better street manners from a "pedal feel" perspective than a long style pressure plate.

Ed

[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.