What happened to my clutch? (long)
10-02-2007, 12:24 AM
#1
Rennlist Member
Thread Starter
What happened to my clutch? (long)
On Saturday, the day of Frenzy 11, my GT was clean as a whistle and ready to go visit with 30 or 40 other sharks.
Or so I thought.
I hopped in, started it up and couldn't get it into any gear for the life of me. It was really weird. The pedal felt completely normal (no squishiness, no unusual travel). The shift movement felt normal as well. Best way to describe the behavior of the shifter is as if I was trying to get into gear without pushing the pedal/engaging the clutch the least bit. The inability to get into gear was as though I wasn't engaging the clutch - regardless of whether the engine was running or not.
The point of engagement of the clutch, the hydraulics and shifting seemed perfect just days before. It seemed really weird to go from a great feeling clutch & hydraulics to no clutch at all.
What popped into my mind was that I'd cleaned the engine and rinsed it with a moderate stream of water the day before. Immediately afterward, I started and warmed up the engine, and parked it in the garage without driving it.
I imagined that the flywheel had gotten wet, and 'rusted' to the clutch disc...as if when depressing the pedal, the disc wasn't lifting away from the flywheel. That was my guess.
I messed around with it for a while, trying to pump the pedal (thinking master or slave blowby), without getting it into gear - not even close. I got the car to a neutral spot (level ground w/no load on the drivetrain). At that point, engine off, since there was no load on the drivetrain, I could coax into gear as any manual with no load on the drivetrain. I tried cranking it from 1st gear with the pedal depressed fully, and it lurched forward as if I wasn't depressing the pedal the least bit.
I checked fluid level - fine; and for fluid leaks at the floor by the pedal & underneath - dry as a bone w/no sign of leakage.
I gave up and took my bike to the Frenzy. Beautiful day, no regrets, had a great time, even without my Shark. Like DR says "it's not just about the cars."
After talking to some of the guys who know these cars inside out, (thanks for the time to troubleshoot John V., Dave R., Dave C.) I was putting my money on air in the slave - or leakage at the slave. Some kind of hydraulic problem. In any case, I was totally expecting to see no or minimal movement of the rod between the slave and the clutch arm as visible thru the bellhousing peephole.
This evening, I got the car up on jackstands and took a look at the movement of the 'plunge' rod (my wife working the clutch). It moved the equivalent distance of the hole, which is maybe 3/4"+. Much more movement than I had expected.
I decided to bleed the slave anyway.
After bleeding, no additional movement. Still seemed adequate, 3/4" or a bit more.
While on the jackstands, I decided to mess with my clutch/shifting again.
I started it up, and couldn't get it into gear at all.
I shut off the engine, and with some gentle coaxing, was able to shift into 1st. I set the parking brake, fully depressed the clutch and cranked the engine.
and BAM! A similar sound to 4 sets of rusted-to-the-rotor brake pads breaking loose a day after putting it away wet after a thorough wash, but louder.
I'm not saying that it was the clutch breaking free from the flywheel, but it sure as hell sounded like something like that.
Anyway, after the BAM!, I have totally normal clutch action, perfect shifting, and complete engagement when the pedal is depressed.
Just like normal.
Was the disc 'rusted' to the flywheel - is this even possible (wouldn't the disc have to be semi-metallic) or was it something else?
Any ideas?
Or so I thought.
I hopped in, started it up and couldn't get it into any gear for the life of me. It was really weird. The pedal felt completely normal (no squishiness, no unusual travel). The shift movement felt normal as well. Best way to describe the behavior of the shifter is as if I was trying to get into gear without pushing the pedal/engaging the clutch the least bit. The inability to get into gear was as though I wasn't engaging the clutch - regardless of whether the engine was running or not.
The point of engagement of the clutch, the hydraulics and shifting seemed perfect just days before. It seemed really weird to go from a great feeling clutch & hydraulics to no clutch at all.
What popped into my mind was that I'd cleaned the engine and rinsed it with a moderate stream of water the day before. Immediately afterward, I started and warmed up the engine, and parked it in the garage without driving it.
I imagined that the flywheel had gotten wet, and 'rusted' to the clutch disc...as if when depressing the pedal, the disc wasn't lifting away from the flywheel. That was my guess.
I messed around with it for a while, trying to pump the pedal (thinking master or slave blowby), without getting it into gear - not even close. I got the car to a neutral spot (level ground w/no load on the drivetrain). At that point, engine off, since there was no load on the drivetrain, I could coax into gear as any manual with no load on the drivetrain. I tried cranking it from 1st gear with the pedal depressed fully, and it lurched forward as if I wasn't depressing the pedal the least bit.
I checked fluid level - fine; and for fluid leaks at the floor by the pedal & underneath - dry as a bone w/no sign of leakage.
I gave up and took my bike to the Frenzy. Beautiful day, no regrets, had a great time, even without my Shark. Like DR says "it's not just about the cars."
After talking to some of the guys who know these cars inside out, (thanks for the time to troubleshoot John V., Dave R., Dave C.) I was putting my money on air in the slave - or leakage at the slave. Some kind of hydraulic problem. In any case, I was totally expecting to see no or minimal movement of the rod between the slave and the clutch arm as visible thru the bellhousing peephole.
This evening, I got the car up on jackstands and took a look at the movement of the 'plunge' rod (my wife working the clutch). It moved the equivalent distance of the hole, which is maybe 3/4"+. Much more movement than I had expected.
I decided to bleed the slave anyway.
After bleeding, no additional movement. Still seemed adequate, 3/4" or a bit more.
While on the jackstands, I decided to mess with my clutch/shifting again.
I started it up, and couldn't get it into gear at all.
I shut off the engine, and with some gentle coaxing, was able to shift into 1st. I set the parking brake, fully depressed the clutch and cranked the engine.
and BAM! A similar sound to 4 sets of rusted-to-the-rotor brake pads breaking loose a day after putting it away wet after a thorough wash, but louder.
I'm not saying that it was the clutch breaking free from the flywheel, but it sure as hell sounded like something like that.
Anyway, after the BAM!, I have totally normal clutch action, perfect shifting, and complete engagement when the pedal is depressed.
Just like normal.
Was the disc 'rusted' to the flywheel - is this even possible (wouldn't the disc have to be semi-metallic) or was it something else?
Any ideas?
Last edited by JPTL; 10-02-2007 at 10:02 AM.
10-02-2007, 12:42 AM
#2
Drifting
I have heard of this happening, but never that quickly. Usually it's a car that been sitting on dirt for quite a while. The moisture from the ground rusts the disk to the flywheel. Another good trick for freeing a stuck clutch is to pour a coke into the bellhousing.
10-02-2007, 03:23 AM
#5
Former Sponsor
I've seen this many times. Had lots of cars towed in for this problem. They can get so stuck that you have to get them rolling in gear and get some vehicle speed to work against the clutch to break them loose. The clutch disc did indeed stick to the flywheel or the pressure plate. Make a practice out of driving your car after washing and this will not happen. The whole car will be happier if it doesn't sit there wet from cleaning.
10-02-2007, 05:42 AM
#6
Addict
Rennlist Member
Rennlist Member
My Landrover used to do it regularly but after a longer time standing. Look upon it favourably at least it probably proves the RMS isn't leaking as the oil on the clutch plate would prevent the rust if it was.
10-02-2007, 09:27 AM
#7
Rennlist Member
Thread Starter
Thanks for reading my long-winded description, and the feedback on this.
Greg, your experiences with this tell me that I'm not crazy.
Focusing solely on the intake and all of the electrical components, I'd always thought that warming the engine to dry it off would be adequate. Your advice to drive the car (any manual for that matter) to eliminate the chance of this happening is spot-on.
I have to assume that when I rinsed around the back of the engine (area under the airbox), albeit lightly, water funneled into the bellhousing through where the clutch arm goes in??? I'd always imagined that the area would be sealed from water, but then again, why should it be?
And Colin, my wallet and I are pleased to hear that this was likely the culprit.
I'm starting to think that a little bit of dust and grunge in the engine bay may be better than some of the outcomes of a not-so-careful cleaning.
No clutch...what a helpless predicament.
Greg, your experiences with this tell me that I'm not crazy.
Focusing solely on the intake and all of the electrical components, I'd always thought that warming the engine to dry it off would be adequate. Your advice to drive the car (any manual for that matter) to eliminate the chance of this happening is spot-on.
I have to assume that when I rinsed around the back of the engine (area under the airbox), albeit lightly, water funneled into the bellhousing through where the clutch arm goes in??? I'd always imagined that the area would be sealed from water, but then again, why should it be?
And Colin, my wallet and I are pleased to hear that this was likely the culprit.
I'm starting to think that a little bit of dust and grunge in the engine bay may be better than some of the outcomes of a not-so-careful cleaning.
No clutch...what a helpless predicament.
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10-02-2007, 09:42 AM
#8
Craic Head
Lifetime Rennlist
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Wow, great post and great feedback. I've never heard of this happening, but now I'm forewarned. Thanks for the detailed description and to everyone who chimed in.
10-02-2007, 11:22 AM
#11
Chronic Tool Dropper
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I have had a similar problem on a few different cars. The problem was not that the disk somehow 'rusted' to the flywheel or the clutch cover, since we are talking about a non-metallic friction material against the flywheel. Nothing for the 'rust' to grab on to. Turned out the metal hub in the disk was sticking on the splined center shaft. The problem can be worse in cars where that splined shaft is worn a bit, since it only takes a tiny bit of corrosion to cause the disk to **** slightly on the worn shaft so it won't move. In cars like the 928, the pilot bearing may also be suspect but typicall that's only after a longer period of soaking in water.
The design of the 928 clutch makes it perhaps the second-easiest clutch to R&R (Saab 99 & 900 get first place in that contest). Pull the stub shaft out and test the fit in the clutch hub. Clean the crud and corrosion off and out of the two pieces, and be sure to lubricate the splines lightly on reassembly. Replace the stub shaft if necessary. There are several common recommendations for splined-shaft lubricants, including spray graphite, Moly-Kote, plain old #2 chassis grease, and anti-sieze. For this service I like that really thick brake caliper slide grease that comes in a small tube. It's thick enough that a thin film won't fly off into the friction faces, and it's waterproof.
My two cents on this, based on over four year of experience.
The design of the 928 clutch makes it perhaps the second-easiest clutch to R&R (Saab 99 & 900 get first place in that contest). Pull the stub shaft out and test the fit in the clutch hub. Clean the crud and corrosion off and out of the two pieces, and be sure to lubricate the splines lightly on reassembly. Replace the stub shaft if necessary. There are several common recommendations for splined-shaft lubricants, including spray graphite, Moly-Kote, plain old #2 chassis grease, and anti-sieze. For this service I like that really thick brake caliper slide grease that comes in a small tube. It's thick enough that a thin film won't fly off into the friction faces, and it's waterproof.
My two cents on this, based on over four year of experience.
10-02-2007, 09:18 PM
#13
Team Owner
Well I would add that if anyone is WASHING their engine they should at a minimum plug the top of the bell housing where the clutch rod attach point is , the reason why this happened for you is that the water rinsed down this hole and soaked the clutch and as a few others have pointed out caused it to rust together, the rusted together isnt the worst part . What usually happens to 5 speed cars is the engine gets washed and water rinses down the hole and ruins the throw out bearing, and the pilot bearing, they soon have a very short service life, if you must clean the engine try using compressed air unless things are oily
10-02-2007, 11:30 PM
#14
Nordschleife Master
So it sounds like I should give my engine a thorough wash before I do my full clutch job (including pressure plate, release bearing, pilot bearing, cup/ball etc.)?
Good to know - I have all the parts to do clutch. I'll plan on getting the engine bay and block pressure washed and degreased right before I do my clutch replacement, and then follow it up with an intake refurb as the cherry on top
Good to know - I have all the parts to do clutch. I'll plan on getting the engine bay and block pressure washed and degreased right before I do my clutch replacement, and then follow it up with an intake refurb as the cherry on top
Well I would add that if anyone is WASHING their engine they should at a minimum plug the top of the bell housing where the clutch rod attach point is , the reason why this happened for you is that the water rinsed down this hole and soaked the clutch and as a few others have pointed out caused it to rust together, the rusted together isnt the worst part . What usually happens to 5 speed cars is the engine gets washed and water rinses down the hole and ruins the throw out bearing, and the pilot bearing, they soon have a very short service life, if you must clean the engine try using compressed air unless things are oily
10-03-2007, 08:10 PM
#15
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Could this be a cause for a ringing like sound after you shut the car off ? Also would that mean the throwout bearing is shot and needs to be replaced?