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.

Please post up the shaft OD and bushing ID so the tranny gurus here can comment on the bushing play. I think it should be pretty tight.

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

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.

Done and back on the road!
 

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.

Don't know why you'd have to oil the bushing. Aren't the made as an "oilite" or something like that? Self lubricating. I went with a roller bearing.

Thats what I was thinking to, they are oilite, should last a very very long time "dry". Sounds like a band-aid putting grease in there, which will, in time, go away. Might you get through the warranty period though... :)

It is common to pack the cavity behind the pilot bearing with grease, shove a shaft in, and hydraulically press the old bearing out. The grease may have been left over in the cavity from previous work long ago.

Isn't this the standard/only way to do this ???? I used Mobil 1 synthetic grease. Is there another way ???


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We used a pilot bushing puller.

No grease was used for either installation or removal of the first two pilot bushings.

I was confused, . . . I meant respond to Excaliber. I was refering to how to lube the bearing. :rolleyes:


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Now I might use what ever grease I have on hand just to aid the input shaft into position upon initial installation. But a pilot bushing is, or should be, oil impregnated metal, "oilite", a material that is self lubricating and generally does not require the addition of grease or oil to perform it's task for the life of the bushing.

To remove one you could use a puller, or pack the opening with grease and then ram an input shaft in the hole to "hydraulic action" force the bushing out. You could also use toilet paper and water, instead of grease, to hydraulic the bushing out.

Just seems odd that someone would recommened grease on a pilot shaft bearing as a long term solution.

Well, the fix lasted about 60 miles.

Shifted beautifully for one day. Then the grinding in reverse and the hard to put into first gear at a stop returned.

I give up! Going to drive it till something either seizes or breaks.

Disconnected the neutral safety switch and will start it in reverse from now on.

Well, as you know, something is hanging up on the clutch or input shaft that keeps the tranny rotating with the clutch "disengaged".

If you have an external slave cylinder, adjust the throw-out rod off the slave cylinder to where it just begins to apply pressure on the throw-out bearing, and then back it off maybe 1/2 - 1 revolution, to get maximum clutch disengagement.

Place 4 equal thickness washers/spacers between the tranny and bell housing, to pull the tranny out a little, to determine if there is any pressure on the end of the input shaft. If this fixes it, then you will need to pull the tranny and grind down the input snout a little.

Interesting problem. Could be worse.

Don't recall if anyone mentioned the clutch disc may be hanging/binding on the transmission spline?
I always spray the spline with a dry graphite liberally then work the disc by hand back & forth over the spline before installation to check for drag, then respray the spline before installing.
I would think with all the miles you have on the clutch this would not be a problem, but you never know.

Craig

Just as an aside to this, it isn't necessary to use grease to hydo the bushing out. Now this is a no **** moment but I tried it and it does work without the grease mess. Use wet tissue or toilet paper. Yeah that stuff can go all over to but it's a hell of a lot easier to clean up than grease!

Steve

Anthony, you are reading my mind.

I have ordered a custom 1/8 inch aluminum spacer from Mike Forte to install between the bellhousing and the tranny. It has an opening in the side so you don't have to remove the tranny to install it. Just remove the four bolts and the rear mount and slide the tranny back an inch or so. Then slide the spacer in and turn it to line up with the bolt holes. Thought about going the washer routine, but was afraid that with only four points supporting the trans, I might bend or break something.

So, I have to wait two weeks for the spacer to be made and then will slide it in and report back. I also think that the bushing should have been put in absolutely dry. The high temp bearing grease that was used probably coked in the first hundred miles and is now causing the drag.

Well, I didn't mean to go drag racing, just maybe drive it gingerly around a bit.

I actually grounded down the snout on my toploader with the tranny assembled, taping around the input spline to prevent shavings from entering the tranny. First cut it off with a die grinder cut off wheel, then ground tapered the edges to slide in the pilot bushing/bearing

I don't know. With the clutch engaged, the spline of the tranny is rotating the same speed as the flywheel, so there is no speed differential. It only occurs when you have the clutch disengaged, i.e. clutch pedal pushed in. There would be no friction when just cruising around in gear. Now, revving the engine while in gear, at a stop, will cause speed differential.

maybe you have done this, but if you haven't check your crank thrust bearing and see how much play you have.And see if it is in spec.

I give up. Now, the trans shifts just fine in all forward gears, but can either grind like heck or be smooth as pie when engaging reverse. Same crap shoot whether hot or cold.

So, I'm going to live with it. I just disconnected the neutral switch and strart the car in reverse in order to avoid any grinding.