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Old 01-05-2014, 06:17 PM   #1
AdmiralSenn
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Default M46 new clutch and pressure plate, how bad is this?

Hi everyone. 1991 740 turbo w/B234 head, M46 with hydraulic clutch, ~170,000 miles. I typically drive it at 10-12 psi, never more than that.

I just recently (one month ago) replaced the clutch with a complete Sachs kit (friction disc, pressure plate, pilot and throwout bearings).

Unfortunately, I got sloppy and forgot to degrease the friction disc, and I believe that either I or the person helping me may have dripped oil on it at one point. The flywheel had some surface cracks but engagement is still pretty smooth, so I don't believe it is in serious need of resurfacing.

Until recently, my car's turbo had a missing bolt in the compressor housing that was causing such a massive boost leak that it was effectively a naturally aspirated B234f as far as power output.

After installation, I had one instance where the clutch produced a significant amount of smoke under normal (out of boost) operation, and one time on an on-ramp where it smoked the entire way up, stopping at around 60mph.

So obviously the clutch now slips under any boost or even moderate acceleration. Typically it only does it in 2nd and 3rd gear, even if I step on it in 4th on the highway it doesn't slip at that point.

I am assuming the clutch disc is now completely glazed or otherwise ruined. Is there any way to fix this, even temporarily? I've tried spraying heavy duty degreaser through the engine speed sensor hole and around the back of the flywheel. It seemed to help but only for a day or so.

Also, is there any possibility that this is the overdrive slipping? The transmission leaked about a cupful of brown fluid out when it was out of the car, and I am waiting for the rain to stop so I can drain and refill the OD. I gather from reading that if it's the overdrive then it's probably not long for this world.

My plan is to eventually acquire an M90 or T5, but I'd like to know if anyone has any suggestions in the meantime to band-aid this until I can drop the transmission again (I rely on it for work and can't really have it down for whole days without some planning).

Thanks.

Last edited by AdmiralSenn; 01-05-2014 at 06:25 PM..
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Old 01-05-2014, 07:16 PM   #2
TrickMick
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massive wash down w/a few cans of CHEAP BRAKE CLEANER...
(drill a hole if you must....keep it OFF the release bearing and pilot bush
as much as possible...) the friction surface is DONE - this will buy you
a few days at most....
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Old 01-05-2014, 11:37 PM   #3
AdmiralSenn
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That's what I thought. I'll try to get that in tomorrow and dial the boost down all the way. Luckily I have a new friend/victim willing to sacrifice his body to help change my clutch.

Thanks.
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Old 01-06-2014, 04:24 AM   #4
munday
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The motorsport way when stuck in a tight situation like this is to buy, agitate and release the full fury of a 2L bottle of full fat coke through the best available hole. This has been done at the Le Mans 24h race to help a team finish when they sprung an oil leak on the rear main seal.
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Old 01-08-2014, 08:29 PM   #5
AdmiralSenn
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I think I might stick with the degreaser since I already have two cans. Right now it does hold enough to drive around, it just doesn't hold any power.

I'm going to call FCP and find out how quickly I can get a new disc. I think I'm going to buy a flywheel and have it resurfaced too, just because.

Do you guys think I need to replace the pressure plate? I did the full kit (clutch disk, pressure plate, pilot and throwout bearings) a month ago, but I don't know if this glazing/slipping problem would affect the PP enough to warrant replacing it again.
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Old 01-08-2014, 11:13 PM   #6
TrickMick
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[QUOTE=AdmiralSenn;4793605]I think I might stick with the degreaser since I already have two cans. Right now it does hold enough to drive around, it just doesn't hold any power.

I'm going to call FCP and find out how quickly I can get a new disc. I think I'm going to buy a flywheel and have it resurfaced too, just because.

Do you guys think I need to replace the pressure plate? I did the full kit (clutch disk, pressure plate, pilot and throwout bearings) a month ago, but I don't know if this glazing/slipping problem would affect the PP enough to warrant replacing it again.[/QUOTE]

INSPECT IT WHEN YOU PULL IT....
heat "checks" and BLUED SPOTS are the end of the surface....
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Old 01-08-2014, 11:33 PM   #7
AdmiralSenn
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Thanks, especially for the picture! I feel like I never know what to look for when people tell me to look for things on a car, so that helps a lot. I will check it carefully. I don't expect that I've damaged the PP in so short a time, I haven't been dumping the clutch or riding it hard, but at least I know what to look for.
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