M38A1 Clutch discovery

Whiskey5 · Post by **Whiskey5** » Mon Dec 29, 2014 8:24 pm

In my tear down I think I've discovered the main reason for this A1 getting parked so many years ago. When I pulled the pressure plate off a handful of pieces fell out. I think I'll just need to replace the disk, and probably the 6 bolts that hold the fly wheel on. Does that sound about right?

G740 · Post by **G740** » Mon Dec 29, 2014 8:46 pm

Pull the flywheel off and have it reground. That one will chew up your new disc and most likely chatter too.
John

4x4M38 · Post by **4x4M38** » Mon Dec 29, 2014 10:42 pm

Mike,
To add what John said, if you are in there go ahead and replace
the whole clutch assembly, release(throwout) bearing as well
as pilot bearing.

That way there won't be any nasty surprises down the road
that will require another tear down.
Just my two cents.

Take care,
Brian

oilleaker1 · Post by **oilleaker1** » Tue Dec 30, 2014 7:04 am

If the flywheel has been resurfaced too many times, the crankshaft bolts will hit the new clutch springs and do it again. Check it before you run it or put it in the Jeep. You may need a flywheel. Looks like a great project you have. Have fun with it. John

Whiskey5 · Post by **Whiskey5** » Tue Dec 30, 2014 9:19 am

Thanks guys. I'll take a few caliper measurements of the flywheel thickness and report back. Any idea what it should be when it is stock?

Post by **wesk** » Tue Dec 30, 2014 9:42 am

If you have read the service criteria in TM 9-1804A and the civvy manual there is no published service limit on thickness of flywheel or pressure plate. The simple statement there is if there is excessive grooving or a step then replace. An experienced automotive machinist will know what he personally limits grinding to. Have both surfaces checked for machineability at the machine shop.

Also the more common reason for clutch disc hub damage is installing the disc backwards. The disc hub projects further out on one side. The side that projects further out goes AWAY from the flywheel (towards the pressure plate). Do you recall which way your hub was facing?

Whiskey5 · Post by **Whiskey5** » Tue Dec 30, 2014 9:51 am

Thanks Wes. I'll clean it up today and have a look. Also, I think the disk was installed properly. Here's a photo of it before I pulled it off.

Post by **wesk** » Tue Dec 30, 2014 11:03 am

That photo doesn't show which way the disc was facing. But your 1st photo indicates the tall side was rubbing against the flywheel bolts indicating it was installed backwards.

oilleaker1 · Post by **oilleaker1** » Tue Dec 30, 2014 6:05 pm

You should replace the crankshaft bolts and nuts/star washers. That can't be done without dropping the oil pan. Don't use junk bolts, get the right ones. You can also simply put the new disc up against the flywheel and check it before you install the pressure plate. You also need to notice the ring gear width and tooth count if you change flywheels. They also have two larger bolts that locate the flywheel to the crankshaft. Some had tapered pins while others were straight shanked. Your engine should time up front on the timing cover so the flywheel should be the one without marks on it for timing. Also install a new pilot bushing in the flywheel, and check the fit of it to the input shaft on the transmission. It might need rheeming. You sure don't want to go back and do this over again. Ask if you get confused or stopped. Advice is free, parts are not. Wes is full of it! (excellent information)

John