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I did some work on an 84 which included installing a new pressure plate, disc and throwout bearing. The master and slave cylinders are probably original were not removed during the work. After a few hundred miles the throwout bearing started making squeaking noises. I discovered that the system is always pushing on the fork and continuously engaging the bearing against the pressure plate. There doesn't appear to be any pedal free play so pulling up on the pedal has no effect. If I push on the pedal the noise stops. If I get underneath and pull the fork back the throwout bearing pulls away from the pressure plate, the bearing stops turning and the noise stops.
Any thoughts on what could be causing this?
I see that the slave and master cylinders are available separately but I think getting a genuine GM replacement that includes the entire system would be best.
In the hyd system in these cars, there's always a TINY amount of tension from the hyd system, against the throwout. What you describe is as it should be. Sounds to me like you just got a crappy throwout.
Replace it, it's fornicated.
If you REALLY want to replace the hydraulics, get the complete assembled, pre-filled, pre-bled setup for a 93-97 Camaro/Firebird V8. Altogether better parts. Not sure whether any of the various 84-92 assys are still available from GM but if they are, those would be OK too if not quite as good. There used to be about 3 or 4 part #s, all will fit and work in AFAIK all installations, they differ only in details like the curvature of the plastic line between the reservoir and the master or between the master & the slave.
But replace the throwout no matter what, that's the thing that's currently "defective" in your situation.
In the hyd system in these cars, there's always a TINY amount of tension from the hyd system, against the throwout. What you describe is as it should be. Sounds to me like you just got a crappy throwout.
My experience with this type of clutch release system, hydraulic or mechanical, was that the throwout bearing should never be constantly turning. Isn't that the case here? That's why I figured what I am experiencing is not correct. I thought that there should be some freeplay. The service manual doesn't help other than it does mention that there is no adjustment. I can't remember if it mentioned freeplay...
Been doing some more research on this issue. It sure is hard to get reliable info on the theory of this type of system. Sofa, you're right on the money about the preload of the bearing against the clutch fingers. Schaeffler Clutches gave me the best answer IMO:
"Hydraulic release systems have a 20 lb spring built into the slave cylinder that puts pre-load pressure on the release bearing and diaphragm spring. As the disc wears, the clutch diaphragm fingers rise and the slave cylinder piston sits further back in the bore, this is what makes them self-adjusting. The noise you're describing sounds like the spring in the slave cylinder is worn out and is not applying enough pre-load on the bearing."
After looking around I was able to get my head around the concept of the self-adjusting mechanism, (and the corresponding preload), except that in years past there always had to be free play to keep the bearing from turning continuously. From 1983's mechanical clutch linkage to 1984's hydraulic system, all of a sudden it was OK to have the bearing preloaded against the clutch fingers. (Maybe they weren't all that susceptible to wear all along).
A rep from McLeod suggested the bearing face might be slipping against the fingers, but his reasoning was that when the bearing is new the grease viscosity is thick enough not to allow it to turn as easily. It should get better as it thins out a bit. When I told him later that the bearing wasn't making any noises until it got about 500 miles on it he didn't have anything to say about that.
I'm still hoping that the bearing isn't going bad from not turning easily enough to keep it from slipping on the fingers. Since the hydraulics are original it would be a good idea to replace it with a new 93-97 assembly anyway.
Another thing to check which is a common problem on the T5s is the squeaking could be coming from the fork itself. In my case I wrestled with it for a while and all that was needed was a dollop of grease on the slave cylinder to fork engagement point and the fork to bell housing ball stud point. Some of them chirp, some don't. Worth checking before you pull the trans again. Easy test is to have it running/squeaking and then hold the fork with your hand. Should go away if it's a vibration issue at either of those points.
I've heard about that too. All associated points were lubed when I installed the clutch/trans.
If the new master/slave cylinder/reservoir assembly does the trick by applying a little more pressure on the bearing I'm hoping that will stop the squeaking. It doesn't take much pressure on the fork to get the bearing to rotate the same RPM as the clutch. The bearing still feels very smooth as it ever did when I press on the pedal. So I'm hoping that's not trashed.
I'll let you know what I find when I install the new parts.
I had the exact same problem. However, the squeaking would only come on after everything was warmed-up (20min + driving). Same symptoms. Just a tad push on fork and squeaking would go away. I was driving with my toe touching the clutch pedal and it was enough pressure to make noise go away. I could also recreate the squeaking just by jiggling the fork around when engine was off and drive train was warm.
Problem was, the bearing was old in age but not in miles. The clutch is not stock but a Centre Force. The Master/Slave were 1 year old. So I changed the throw out bearing and called it a day. The kicker is, I haven't had a chance to really test drive it for a while, so I might get surprised. I just went with the most probable cause. The bearing had some play and the fork was vibrating a lot. Everything was well lubricated. The preload was identical to the old master/slave. However, It did cross my mind that maybe the pre load was different from the OEM set-up vs after market. I used LUK LMC118/LSC110.
Once I get it on the road, I'll repost to confirm that was the problem.
I had the exact same problem. However, the squeaking would only come on after everything was warmed-up (20min + driving). Same symptoms. Just a tad push on fork and squeaking would go away. I was driving with my toe touching the clutch pedal and it was enough pressure to make noise go away. I could also recreate the squeaking just by jiggling the fork around when engine was off and drive train was warm.
Problem was, the bearing was old in age but not in miles. The clutch is not stock but a Centre Force. The Master/Slave were 1 year old. So I changed the throw out bearing and called it a day. The kicker is, I haven't had a chance to really test drive it for a while, so I might get surprised. I just went with the most probable cause. The bearing had some play and the fork was vibrating a lot. Everything was well lubricated. The preload was identical to the old master/slave. However, It did cross my mind that maybe the pre load was different from the OEM set-up vs after market. I used LUK LMC118/LSC110.
Once I get it on the road, I'll repost to confirm that was the problem.
Problem fixed. It was indeed the throwout bearing squeaking.
Problem fixed. It was indeed the throwout bearing squeaking.
300 miles later and the new Delco OEM style throwout bearing has failed!!!!! Started with squeaking again and turned into a grinding noise. Squeaking would come on after hard acceleration with 6000rpm shift and would go away after a few minutes of easy driving.
I did drag race a lot with higher rev than stock (6K rpm). Wondering if the 383 with high rev shift is not destroying the OEM style throwout bearing? Delco is also made in China.
Will try a Hays high performance style 70-101. That's all I could find.
"383" has nothing to do with it. The throwout can't see that and does not care.
"High rev shift", now that might be another matter.
It's true that good parts like that are harder to come by nowadays. Pay less attention to romantic and warm/fuzzy names on boxes like "Delco" and LOOK AT THE PARTS THEMSELVES before you lay out your long green and walk out of the store with them.
"383" has nothing to do with it. The throwout can't see that and does not care.
"High rev shift", now that might be another matter.
It's true that good parts like that are harder to come by nowadays. Pay less attention to romantic and warm/fuzzy names on boxes like "Delco" and LOOK AT THE PARTS THEMSELVES before you lay out your long green and walk out of the store with them.
I kindda figured the engine torque had nothing to do with it but needed confirmation. Thanks!
Part looked pretty good actually! However, it would be hard to see, with a naked eye, mistakes in tolerances and bad quality material (contamination).
I don't have to walk, it just gets shipped, but I get the point
I'll let you know on the Hays performs.
Well! Looks like the AC Delco failed. All the grease slung out of it and coated the bell housing and pressure plate. Nice mess. Grease came out of where the arrow points. The back red seal was loose also.
Installed the Hays 70-101. Looks less likely to fail as the entire front face is sealed. Only time will tell.
Well, well, well... 100 miles and the Hays TOB is already squeaking!!!!!! No hard driving this time.
Now I am starting to think the Centre Force (CF) pressure plate (PP) with its weight system might have something to do with it. I peaked through the clutch fork hole and saw the TOB's side had marks + some metal shavings were flung around the bellhousing. Not good! I can see the weights are off center and contacting the TOB's side. Not good either. I also noticed the last time I change the TOB the weights were shifted completely to one side and the ring was stuck between the fingers and the cover (see picture). Had to bang on them to loosen them up and recenter. Not good at all.
So.... will take the tranny out again and investigate. I will remove the weights. At this point I don't care.
I had a DF clutch in my car up until recently. IIRC they're pretty adamant to using a Centerforce tob with it. I used that clutch for close to 20 years without a squeak.
I had a DF clutch in my car up until recently. IIRC they're pretty adamant to using a Centerforce tob with it. I used that clutch for close to 20 years without a squeak.
Had no problems with DF for 13 years with oem style tbo, until this.
My hays just started to chirp again time to go to another brand. What did you end up trying next?
Got a complete kit from McLeod #75225 which includes throw out bearing.
I think the CF pressure plate was the problem. The ring was off centre again squeezed between fingers and cover. I could see the whole thing vibrating through the clutch fork hole. The Hays bearing was completely loose from the vibration.
I believe as the clutch wore out, the gap between the fingers and cover got smaller getting the ring caught in it. But, I also noticed the weight marks were uneven as if the ring was never centred properly.
one thing for sure, I’m done with this type of pressure plate. Weights = one more thing to go wrong.
Just a theory for now. I’ll have everything on the road soon and we’ll see
Heres some pictures:
Ring stuck Pry bar to unstuck Weight marks show an off centre wear pattern
Honestly the best quality one I've seen is the Centerforce one I have. The one that came with the Mcleod has kinda sloppy tollerances compared to it. I debated on putting in the centerforce tob instead.
All put back together, road tested and inspected. It seems like the clutch fork vibration is way way better. I started braking in the new clutch, so I take it easy and cycle through the gears, stop and go.
The bearing can't really "wobble". It's constrained by the clutch gear bearing retainer, aka the thing that sticks out of the front of the transmission around the clutch gear ("input shaft" to non-manual-trans people). The TOB fits fairly tight to that.
Now, if the CGBR is worn where the TOB slides along it, then the bearing COULD wobble; which is why that part should always be inspected carefully and replaced if it has wear that can be felt. In this photo for example you can see the shiny spot of wear on the 2nd design (bottom) one, although this one isn't bad enough to need replacement. They can get ALOT worse.
Also, when you bolt up the clutch to the flywheel with a disc in between, those fingers move. ALOT. After all, they are the opposite end of the spring that grabs the disc, which is basically a giant Belleville washer with its inner diameter split up into those "fingers". Without being installed, they may or may not be level, even, or anything else, all of which might change when the spring (fingers) is compressed.
The bearing can't really "wobble". It's constrained by the clutch gear bearing retainer, aka the thing that sticks out of the front of the transmission around the clutch gear ("input shaft" to non-manual-trans people). The TOB fits fairly tight to that.
Now, if the CGBR is worn where the TOB slides along it, then the bearing COULD wobble; which is why that part should always be inspected carefully and replaced if it has wear that can be felt. In this photo for example you can see the shiny spot of wear on the 2nd design (bottom) one, although this one isn't bad enough to need replacement. They can get ALOT worse.
Also, when you bolt up the clutch to the flywheel with a disc in between, those fingers move. ALOT. After all, they are the opposite end of the spring that grabs the disc, which is basically a giant Belleville washer with its inner diameter split up into those "fingers". Without being installed, they may or may not be level, even, or anything else, all of which might change when the spring (fingers) is compressed.
All good info thanks.
The CGBR is fine in my case. The outer part of the TOB will wobble (observed with my peepers through the clutch fork hole). The inner part stays quite stable but the outer part follows the clutch fingers. That is what destroys the TOB, it gets a lot of play. I should have checked the fingers when it was installed. But from what I observed, there is no doubt that's what was causing the problem. The McLeod's fingers were quite level. The TOB and clutch fork don't vibrate (wobble) anymore.
03-12-2023, 04:54 PM
