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After a tune-up this weekend, my clutch progressed from slipping some of the time to slipping almost all the time. I had the disc out when rebuilding the engine and it looked like it had lots of meat, almost like it was brand new.

Clutch pedal free play is good.

The local AAMCO transmission guy says everything looks fine as assembled and he wont know what the issue is until I remove the pressure plate and disc. His only suggestion was that the disc may need to be thick.

How thick is a new clutch disc?

Thanks

Hey TBone,
I just happen to have my brand new clutch pulled out, waiting for a new flywheel. I'll measure the thickness tonight and post the number in the morning.
Gary

Hi TBone,
As promised: 5/16 thickness for the brand-new disc (well it has 10 miles on it, I'd still call it "new" though).
Gary

Thanks Cal_Gary, I'll crawl underneath and measure mine tonight.

Every M37 slipping clutch I have ever had was the result of soft springs in the pressure plate or oil leaking from the rear main seal soaking the disk but usually it was just an old worn out pressure plate. Disk thickness didn't cause slipping as I've seen them worn down to the rivets and still holding and although noisy still working.

The last time I had a slipping clutch, I just took it in and had it rebuilt. Here's the repair ticket for replacing the clutch in my 1950 Plymouth. The pressure plate and the friction disc were for taxi cab use - the equivalent of "heavy duty" back then. It only cost $47.15.

Of course, you may have some trouble finding a DeSoto - Plymouth dealer these days.

Paul, the parts replaced list shows rebuilding of the pressure plate was done, but also lists new disk and pilot bushing, but what's the word before "brg". it looks like shows some ditto marks and then something "assy brg"? I know it's the clutch release bearing, but what does it say?

I suspect that some of those taxi cab parts used might have been the same as the 3/4 ton truck clutch parts.


Carter

Another possible condition would be a glazed clutch disk. This is a common issue with folks (like my wife) who tend to "ride" the clutch. Just the pressure of resting your foot on the clutch pedal can cause the clutch to slip enough to polish the disk. It can also be caused by improper adjustment of the clutch linkage. The only cure for this condition is a new clutch disk and remedial training of the driver/mechanic.

Ha, remedial training! Which reminds me that when I got this truck, along with many other issues like a thrown rod, hole in the block from said rod, hackjob electrics with all wires in yellow, the fording plug was in the clutch housing, stopping up about a quart of oil.

I didn't think much about it at the time as there were plenty of other things to do to get it running.

But now, like a smack in the head, oil contaminated clutch disc! That's at least part of the problem.

A quart of oil in there means more work-either your engine rear main seal and/or your transmission input seals are shot....
Gary