Clutch/Throw out Bearing/Pilot Bearing Noise???

[Racinfan83]

I had a bit of this noise last year, once in a great while. Yesterday after being in hibernation since late October, I got the car out and wife and I went out around the Metro for a cruise. This noise is WAAAAAY worse now. I THINK it is the Throw out Bearing - but I am far from a clutch fix it expert. The noise sounds like metal on metal squalling/grinding that varies in pitch, it is intermittent but is now happening a lot more. Happens sometimes for a split second when shifting gears, most prevalent when pressing in the clutch at a stop though. Happens anywhere from mid pedal to the floor, sometimes lasts for a few seconds sometimes just a split second. Clutch function seems good, releases about 2/3 of the way up. Car has 20900 miles on it.
SO - what do you guys think it is, how concerned do I need to be about it, is there a way to lube it or fix it, am I looking at a tranny drop and complete clutch replacement, etc? If so - then what one is the best for the buck? Funds are limited now so keep that in mind with your answers....

[Dynomite]

Originally Posted by Racinfan83

I THINK it is the Throw out Bearing Yes

how concerned do I need to be about it, Replace Thowout Bearing

is there a way to lube it or fix it, NO

am I looking at a tranny drop and complete clutch replacement, etc? Trans Drop only and Bell Housing/Pressure Plate if you want to replace Pilot Bearing....(I use Needle Pilot Bearings). Your Clutch Disk should be OK with only 20K miles but if you are replacing Pilot Bearing....then check and possibly replace Clutch Disk since you have Bell Housing and Pressure Plate removed. But you can solve your existing issues with only Trans Drop and Throwout Bearing replace.

If so - then what one is the best for the buck? Funds are limited now so keep that in mind with your answers....

You really need to lift the Z about 18 inches with Jack Stands under each corner. And.....you really need a Transmission Jack especially for the repositioning and alignment of the Transmission so you can properly engage the Pilot Bearing. Maybe someone can lend you a Trans Jack.

Remove Exhaust from Headers and Remove C-Beam (When doing all this you support the engine under the oil pan with hydraulic jack (with short 2x4 between jack pad and oil pan).

Drain Transmission Oil (Have on hand Fresh Transmission oil). Disconnect Drive Shaft universal joint at Differential (first mark drive shaft at the Differential so it gets installed the same) and pull driveshaft out of Transmission.

Good time to install ZFdoc C4 Beam Plates.

TRANSMISSION
Post 35 - Pilot Bearing
Post 36 - ZR-1 Transmission Install and Lift Tricks
Post 37 - Vibration Issues Diagnosis
Post 38 - Throwout Bearings and Clutch Forks
Post 39 - C4 Beam Plates and Installation

[Racinfan83]

Thanks Dyno!

[Paul Workman]

Yep! I agree w/ Cliff on all counts. However, far as the trans jack goes, Bill Boudreau told me he never uses one; prefers to balance it on the "cup" of the floor jack. Being a cheap SOB, that's the way I've always done it too, as result.

Those C-beam plates are worth every penny! Much better grip and less chance of wallowing out the bolt holes on either end of the C-beam and the issues that result from that. But, if for no other reason, it simplifies the removal and installation of the C-beam to the point of being no more difficult than removing spark plugs (once you have the car on jack stands).

[Dynomite]

Originally Posted by Racinfan83

Thanks Dyno!

Just Remember I DID mention the Pilot Bearing
Trans Drop only and Bell Housing/Pressure Plate if you want to replace Pilot Bearing....(I use Needle Pilot Bearings). Your Clutch Disk should be OK with only 20K miles but if you are replacing Pilot Bearing....then check and possibly replace Clutch Disk since you have Bell Housing and Pressure Plate removed. But you can solve your existing issues with only Trans Drop and Throwout Bearing replace.

By the way.....I Do use Needle Pilot Bearings Jerry's Needle Pilot Bearing

It is hard to imagine only 20K miles needing a Pilot Bearing but anything is possible. It is also hard to imagine only 20K miles needing a Throwout Bearing But I concluded that was most possible

[Racinfan83]

UPDATE: Here we go. Long post, but worth it for the info...

I emailed Marc Haibeck with the same info I posted above to see what he thought it was. He replied that the throwout bearing (TO in rest of post for brevity) rarely makes noise like that and most likely it was the Pilot Bearing (PB in rest of post). He suggested I change it out to the roller PB, GM #14061685, and that with only 20k miles the clutch/TO should be fine.
So then - having two differing opinions from two people who know WAAAY more then I - I decided to email Bill Boudreau the ZF Doc - kinda to "break the tie". He wrote me a detailed email and suggested I post the info so others can benefit from his knowledge. Here it is verbatim:

Hi Eric,

Please pass this information on to anyone else that may benefit from knowing this type information.

Marc Haibeck is correct, it is a faulty pilot bushing for sure judging by your description which was very good by the way. To fix this problem, the exhaust, driveshaft, driveline support beam, transmission, bell housing and clutch assembly will have to be removed in order to remove and reinstall a new pilot bushing. What causes a pilot bushing to fail? Grease applied to the inside diameter surface of an oil-lite (oil saturated) pilot bushing is the number one cause for pilot bushing failure. Grease applied in a pilot bushing eventually dries up and clogs the otherwise normally self-oiling pours of the bushing. When installed clean and dry, a pilot bushing should typically provide up to one million release cycles of service whereas when grease is applied, the bushing service life is drastically reduced down to approximately 5000 cycles or less. Typical time to failure with a grease contaminated pilot bushings is around 1.5 years from time of contamination.

The purpose of the pilot bushing is to provide centering support of the input shaft at the far end for maintaining optimal clutch disc to friction surface alignment. With loss of pilot support integrity at the far end of the input shaft comes accelerated wear of the clutch disc friction surface at the outermost region of the disc.

GM has a revised design of the pilot bushing called a fluted pilot bushing (GM P/N 10125896) which has six narrow grooves formed on the inside diameter surface of the bushing which act as scrubbers to prevent glaze from forming on the input shaft pilot tip leading to pilot failure. GM also makes a pilot needle roller bearing of which many people prefer over using an oil saturated brass bushing. The reason I prefer bushing over roller bearing type pilot is because when a bushing fails it usually does not compromise the input shaft pilot tip surface. In the rare event of a pilot roller bearing type failure, the input shaft pilot tip surface is typically compromised requiring disassembly of the transmission in order to replace the input shaft or to have a machine shop install a new pilot tip surface on the input shaft doubling or tripling the repair cost over just replacing a compromised pilot bushing.

For the sake of my ongoing pilot failure study, I have a few questions.
Are you the original owner of the vehicle? If not, do you know if the clutch was possibly serviced prior to your ownership of the vehicle?

It’s not that uncommon to come across some ZR-1s whose initial owners over-taxed the clutch and dual-mass flywheel while driving it at 10/10ths for many quarter miles at a time without allowing cool-down between runs, or inversely, not allowing the clutch to get up to temperature before whaling on it This type information is rarely passed on between vehicle owners with forensic evidence being limited to dealer service records during warranty of the vehicle only. More often than not, GM service technicians that I have spoken to where not aware that applying grease to a pilot bushing will compromise the bushing in a fraction of its normal life expectancy. The saddest part is finding out that thousands of NOS OEM high quality Valeo clutch kits have been consumed over recent years and needlessly compromised due to this technical/procedural misunderstanding/oversight.

What about replacement parts? Unless you contact someone like Jim Jandik of Power Torque Systems http://www.powertorquesystems.com/Contact.htm who somehow manages to find an occasional NOS OEM Valeo pressure plate to sell with one of his clutch kits, replacing your clutch will likely end in disappointment due to a replacement pressure plate made in China whose diaphragm spring performance quality is best described as hammered dog ****. Also good to know, Jim has a local machine shop that is capable of resurfacing C4 pressure plate and dual mass flywheel friction surfaces without compromising balance or seal integrity of the dual mass flywheel damper.

With the few amount of miles you have on your ZR-1, I would not be surprised if you only end up having to replace the pilot bushing and possibly the clutch disc after scuffing the friction surfaces enough to remove any surface glaze by hand only using a maroon scotch-brite pad. If you send me or Jim pictures of both sides of your clutch disc along with thickness measurement, we can review and advise on disc replacement. Jim also provides a clutch hydraulic cylinder rebuild service which is a better corrective action than replacing with inferior China made clutch hydraulic cylinders.

Installing C4 Beam Plates will help improve performance of the vehicle torque management system by reducing lateral deflection occurrence around the union joints at both ends of the driveline support beam.

Hope this helps.

Best regards,

Bill Boudreau

OK - sounds like PB went bad for some unknown reason according to two of the ZR-1 experts. But now I have one suggesting ROLLER PB, and one suggesting FLUTED PB. Once again, to "break the tie", I emailed another expert on the subject - Jim at Powertorque Systems. He confirmed that it is very rare for the factory TO to go bad - and that it is a HUGE chance it is PB. He also said the FLUTED PB is the way to go - and that it is one of the very few things he and Marc disagree on. With me not knowing if anyone has been in the clutch before - it is POSSIBLE that someone destroyed a clutch system in the car sometime before I got it, and the TO was replaced with one of the chinese ones that don't last. He told me that there will be an "INA 04" on the dust boot of the TO if it is the factory original - and if I find that there is very little chance of the TO being bad. He also thinks I may be OK on the clutch disc - I will measure thickness and take pics of it and the flywheel, and have him decide if it's worth putting back together with only a new PB.
SO - not real certain from any correspondence/conversations WHAT COULD CAUSE the PB to go out with so few miles. AND it still could be the TO, or both. I have decided to bite the bullet and put the car up on jackstands, and do this job myself. It's gonna take me awhile as I've never done this big a project before, and only have a few hours a week I will be able to work on it. I have read in the "solutions", printed, made notes, etc so I know most of the tricks and "Dont's". Working on getting everything together now, and I left a message on Bills VM, waiting on a call back so I can order the C Beam plates. Save labor $ = buy more parts..LOL Gonna install drain plug in differential as part of this deal too.
Will let Ya'All know what I find when I get it apart - and I'm sure I will be posting questions as I go along...

[Dynomite]

Great information and keep us posted on what you find when you disassemble your Clutch assembly

I linked your post above in -Solutions- under Transmission.

[Racinfan83]

Hoping to have it apart before the end of the month - have another big moving project that HAS to be done by the end of the month however - so we'll see what happens. Between being shorthanded at my work and lots of overtime, doing most all the housework (wife works 2 jobs), volunteering with two animal rescue organizations, etc - my playtime is limited. At least the guy I've been crewing on his Dirt Modified for 20 years, sold out and retired after last year so I don't have that....

[Racinfan83]

UPDATE: I have it apart.. (mostly)
Got the thing apart today. Trans came right off with no issues. Bellhousing was another story. Since I have never removed the trans/clutch/pilot bushing I printed up three different things on how to do it, and was trying to "follow to the letter" the instructions given by people who know much more then I. Well - after over an hour of tearing the heck out of my shoulder and who knows what else trying to wedge screwdrivers/prybars in between the BH and block to get it off - I discovered it helps a LOT if you take that half moon flywheel shield off FIRST... I guess that should have been somewhat self-explanatory but once again I am trying to do things by the book this time...
My next problem is that I cannot get the pilot bushing out. Got a puller, and broke 3 different setups on it - don't think the thing budged. Which A: makes me wonder if the bushing was the problem or is it the Throwout..
And B: now that I have scarred up the pilot bushing - I HAVE to get it out - any suggestions?
Gonna throw up some pics - might take two posts. Please let me know if anyone sees any issues in the pics. I have also sent them to Jim Jandik at Powertorque Systems for his expertise. He has been quite helpful on the phone..

[Racinfan83]

The INA04 on the seal means this is the oem throwout according to Jim..