I just replaced the clutch on a 72 SB with a Muncie. After about 500 miles I started getting a noise from the pilot bearing. Pulled the tranny back out and replaced the pilot thinking that was the problem. I was checking the input and lubing it for the re-install, when I noticed that the shaft had a lot of vertical/horizontal play in it. Could this be the part of the problem, causing the noise in the pilot?
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Re: C3..Pilot bearing problem.....
Sounds normal. -
Re: C3..Pilot bearing problem.....
have you went through the trans?Comment
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Re: C3..Pilot bearing problem.....
Tranny was overhauled 2-3 years ago, 3-4000 miles, evrything new, synchros, seals, bearings etc. I think the clucth was not adjusted properly, and it wore out prematurely. when I put this new one in, I had to resurface the flywheel too. With the old clutch, I didn't have this problem. The pilot bearing problem has just surfaced since the new clutch. New clutch works nice and smooth , no chatter, just smooth except for the noise periodicallyComment
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Re: C3..Pilot bearing problem.....
You lost me on the "sounds normal". It's NOT normal for the noise.....Comment
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Re: C3..Pilot bearing problem.....
Bruce:
It would be helpful if you could give a better more specifc description of "noise", and when it happens. Clutch in/out? In gear/out.
I think what Wayne was referring to as normal was the apparent sloppiness of the input shaft. This may be normal or it may not. Depends on how much.
I honestly don't think I've ever heard a pilot bearing make noise.Comment
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Re: C3..Pilot bearing problem.....
I agree with Mike. A pilot brng is only acting as a bearing when the clutch is depressed and the transmission is in gear. Even at that, there's no load on the pilot brng so it's not likely that you would ever hear a noise, even if the bearing was bad.
The most common noise would be a squeal or moan as the clutch is being released and that usually occurs with the pedal about half way up. Often times, the inner sleeve of the T/O bearing spins for a second or two on the transmission front bearing retainer.
Try to more accurately describe the exact conditions when you hear the noise. (clutch depressed/clutch engaged/in gear/in neutral etc.Comment
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you may have been hearing
transmission "rear rattle" if the noise was in neutral with the clutch depressed caused by the tighter pilot bushing causing the input shaft to turnComment
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Re: C3..Pilot bearing problem.....
Mike and Michael......Thought it would be a "no brainer". I thought I had covered it..... 1st gear, dead stop/barely rolling in traffic, clutch half way up, squealing sound, clutch all the way out, 2nd gear shift, no noise. It ONLY happens when you are starting off, nothing in neutral with the clutch depressed. ONLY when you are in 1st, haven't noticed it in reverse. The complete clutch (LUK 10.5") comes with throwout bearing and its got less then ,5-600 miles on it. I've heard of the pilot going dry, cars that have sat for a long time, only get driven 2-3 months of the year, but this is brand new. I soaked the pilot in oil and then "forced " oil into it for a period of time.....I've had 4 speeds for years, and only seen one other ( just in the last month coincidentally) that the car is stored for the winter and the clutch has been in it for yearsComment
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Re: C3..Pilot bearing problem.....
Bruce,
This was actually a very common problem and it goes all the way back to the 60's and 70's when these cars were new. The noise seems to occur only when the clutch is being engaged in 1st gear, and only at the friction point, just as you described. We could never seem to duplicate the problem in any other mode. It doesn't occur when pushing the clutch in or if the car is in neutral but only on release in 1st gear. GM engineering claimed it was the inner sleeve of the throw out bearing rotating on the transmission front bearing retainer. It wasn't rotating smoothly however. It was rotating elliptically around the retainer which causes the weird noise. The fix, at that time, was to replace the T/O bearing AND the transmission front bearing retainer. That cured the problem most of the time.
I see there is a new design bearing available today that has some interlocking feature that keys the bearing to the retainer which would positively prevent the inner race from spinning. I don't remember who makes it but there was some discussion of it right here on this board within the last week.
MichaelComment
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Re: C3..Pilot bearing problem.....
Michael:
Whoever posted it said the part of the throwout bearing that fits in the fork was now egg shaped or oval. This, of course would prevent the rotation you are talking about.
I've not seen one.Comment
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Re: C3..Pilot bearing problem.....
Yes, I now remember it being keyed to the lever. Not sure why I thought it was the retainer but I remembered it was keyed to something.
I should have mentioned in my previous post to Bruce, there's no need to prelube a pilot bushing. They're self lubricating, by design, and require no further lube for life. They're bronze instead of brass, with roughly 10% tin added and perma lubed. Even at that, I know we all still add a bit of some lube when assembling and it can't hurt but it's not necessary. (I still do it)
I now remember some of the GM tech sheets on this problem. It was basically caused by a slightly off center pressure plate diaphragm. If the tips of all the diaphragm levers don't rotate off of the exact same C/L as the input shaft, it will cause the T/O bearing to try to rotate eccentrically instead of following the true C/L/, and that caused the inner sleeve to rotate at some certain pressure. (during release)
The other problem that was discussed was uneven diaphragm finger height which would most likely be caused by an uneven clutch disk thickness.
In any event, the new front bearing retainer or the new locking style bearing will prevent this problem, I hope. I remember several cases where the bearing and retainer were replaced but the unit returned to the dealer within a month or two with the same problem. I vividly remember one red/red 67 435 that returned four times. (I still remember the VIN)
MichaelComment
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some trans came with a aluminum
front bearing retainer that the TO bearing slides on and the aluminum would get rought and not allow the TO bearing to move smoothly. replace it with a steel one. this has nothing to do with this problem BUT i thought you would like to knowComment
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Re: C3..Pilot bearing problem.....
Michael:
You seem to have a pretty good grasp of this problem. Let me ask you this: would you care to speculate what would happen with this situation if left unaddressed? Better, worse, go away completely?Comment
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Re: C3..Pilot bearing problem.....
Mike Hanson....Can you give me a brand name or some specifics on the TO bearing? What I did notice when I put the new TO bearing in was that it had 2"keyways", flat spots on the fork side. The one I took out didn't have this, and I can't remember seeing this before. ( I don't do a lot of clutches, they just don't wear out)
As to not needing to lube the pilot. When I pulled the tranny to look at it, the pilot was dry to the touch, the input was marked from the pilot, and I was taught that it had to be lubed.
Now I didn't have the problem before I changed the clutch, so I'm thinking its NOT the bearing retainer.
I'd like to know about that new design bearing retainer.......ThanksComment
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