Clutch Question

1941 - 1945, MB, GPW Technical questions and discussions, regarding anything related to the WWII jeep.
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twinflyer17
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Clutch Question

Post by twinflyer17 » Mon Mar 19, 2018 6:48 am

Quick clutch question:

The clutch on a friends MB doesn't fully disengage. We were initially unsuccessful with the few things we tried, then he had a reputible jeep mechanic take a look. The ultimate conclusion was that there was no grease at the end of the input shaft, where it rests in the flywheel bushing. The mechanic supposdely added a bit of oil to the shaft and was able to fix the problem...at least until now. Seems the same problem is happening again. I've posted this before, but here's the link to a video of the clutch, showing it not fully disengagin: https://www.youtube.com/watch?v=qug3PDaUYOg

Does anybody have any ideas as to where, how, and what kind of oil can be added? I'm thinking it needs to be added to the transmission input shaft, but I'm concerned that adding too much will cause it to drip onto the clutch disk, thus creating even an even larger problem. I'm also thinking if this doesn't work, it probably makes sense to pull the engine and add grease to the end of the input shaft, instead of using oil.
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Re: Clutch Question

Post by Joe Gopan » Mon Mar 19, 2018 7:46 am

Why prolong the obvious, there is a mechanical issue that keeps returning to haunt. Best to repair it and enjoy some worry free miles.
That Pilot Bushing is graphite impregnated and is self lubricating.
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Re: Clutch Question

Post by twinflyer17 » Mon Mar 19, 2018 7:58 am

Thanks, Joel. Never realized that. Any thoughts as to what the actual problem may be then?
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Re: Clutch Question

Post by Joe Gopan » Mon Mar 19, 2018 8:38 am

My guess is wear.
The Jeep service schools of yesteryear to put a dab of light grease in the pilot bushing, the suggested grease back then was Lubriplate 630 AA (I still use it), the same stuff the Army greased the M-1 Garand Bolt Lugs.
I also put a very light smear of 630AA on the input shaft splines, do not butter it on. Some choose to wipe a little kerosene on the splines, and some choose to just leave the splines dry.
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Re: Clutch Question

Post by artificer » Mon Mar 19, 2018 8:44 am

Joel wrote: That Pilot Bushing is graphite impregnated and is self lubricating.
Some pilot bushes may be, but all are not, in my practical experience. The TM indicates that one should grease the spigot bush when assembling the clutch for good reason.
Biting the bullet, I agree with.
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Re: Clutch Question

Post by Joe Gopan » Mon Mar 19, 2018 8:54 am

I have never seen any parts books OEM or aftermarket with reference to a Jeep pilot bearing that is not Bronze Graphite.
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Re: Clutch Question

Post by twinflyer17 » Mon Mar 19, 2018 9:00 am

artificer wrote:
Mon Mar 19, 2018 8:44 am
The TM indicates that one should grease the spigot bush when assembling the clutch for good reason.
Unfortunately, this MB wasn't greased when reassembled. My biggest question, could this actually be the cause of the problem? Based on what Joel said, seems like some will overload the input shaft with grease, while others leave them dry. If it's not a grease problem, could it be related to other clutch components?
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Re: Clutch Question

Post by Chuck Lutz » Mon Mar 19, 2018 9:06 am

I too believe that the bushing and main shaft are binding. I also agree you are probably looking at replacing it. However, let's ask a couple questions beforehand to try to avoid the problem from re-occurring. Did the assembly of the flywheel-to-block include the special bolts indicated below? was the bushing soaked in oil overnight prior to installation? Did the owner try to fit the T-84 into the bushing after the bushing was put into the Flywheel? I ask because it happens that installing it can deform it slightly which may also cause binding after heat dissipates the lubricant.

In addition, if the T-84 is aligned a little off of center, which can be done by the way, when it is bolted to the bellhousing because the bellhousing is not be aligned properly....the problem may re-occur. Check to see he has those two special bolts and if not, report back as I know so many guys go through these posts when they have a similar issue and often the OP never responds with what the solution to the suggestions posted turned out to be.

So...I believe the owner needs to replace the bushing in the flywheel, check the fit of the main gear into it, then put a dab of grease in the bushing prior to attaching the bellhousing, and THEN using those special bolts to insure alignment is correct....tighten up the other bellhousing bolts. A quick wipe of grease on the tip of the main gear as the T-84 is bolted up should insure the problem does not come back again.
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Re: Clutch Question

Post by twinflyer17 » Mon Mar 19, 2018 9:22 am

Thanks, Chuck. I helped to install the engine, so I have the answers to your questions:
Chuck Lutz wrote:
Mon Mar 19, 2018 9:06 am
I too believe that the bushing and main shaft are binding. I also agree you are probably looking at replacing it. However, let's ask a couple questions beforehand to try to avoid the problem from re-occurring. Did the assembly of the flywheel-to-block include the special bolts indicated below?By special bolts, do you me the flywheel dowels? Yes, those were included. was the bushing soaked in oil overnight prior to installation? The flywheel was actually NOS and had the bushing already installed.Did the owner try to fit the T-84 into the bushing after the bushing was put into the Flywheel? Yes,
we test fit the flywheel, with bushing, over the input shaft to ensure it properly fit, which it did
I ask because it happens that installing it can deform it slightly which may also cause binding after heat dissipates the lubricant.

In addition, if the T-84 is aligned a little off of center, which can be done by the way, when it is bolted to the bellhousing because the bellhousing is not be aligned properly....the problem may re-occur. If all bolts were tight against the bellhousing,
block, and transmission, how could it not be aligned?
Check to see he has those two special bolts and if not, report back as I know so many guys go through these posts when they have a similar issue and often the OP never responds with what the solution to the suggestions posted turned out to be.

So...I believe the owner needs to replace the bushing in the flywheel, check the fit of the main gear into it, then put a dab of grease in the bushing prior to attaching the bellhousing, and THEN using those special bolts to insure alignment is correct I think I'm confused as to what bolts you're referring to here.....tighten up the other bellhousing bolts. A quick wipe of grease on the tip of the main gear as the T-84 is bolted up should insure the problem does not come back again.
I'll definitely post the solution here when we find it. Thanks everyone!
Sean

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Re: Clutch Question

Post by Joe Gopan » Mon Mar 19, 2018 9:26 am

And you have looked to see if the disk is not installed backward? Is the Pivot Ball (Fulcrum) original? Is the Pivot Ball worn thru the dimple on the fork?
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Re: Clutch Question

Post by twinflyer17 » Mon Mar 19, 2018 9:36 am

Ben Dover wrote:
Mon Mar 19, 2018 9:26 am
And you have looked to see if the disk is not installed backward? Is the Pivot Ball (Fulcrum) original? Is the Pivot Ball worn thru the dimple on the fork?
Not sure about the pivot ball, but we replaced the fork when he started having these issues. And disk was correctly installed. He had actually driven the jeep 500+ miles with zero issues before this started to happen...
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Re: Clutch Question

Post by Chuck Lutz » Mon Mar 19, 2018 9:44 am

The diagram below shows the two special bolts that will align the bellhousing to the block correctly which in turn will align the T-84 main gear nose to the bushing in the block. You had the flywheel/crank dowel bolts which align the flywheel to the crank....you need the bellhousing dowel bolts to align the bellhousing to the block...
Bell Housing Bolting Instructions Iowa.jpg
Bell Housing Bolting Instructions Iowa.jpg (45.96 KiB) Viewed 980 times
Bellhousing Dowel Bolt 2 and one eighth long.jpg
Bellhousing Dowel Bolt 2 and one eighth long.jpg (51.35 KiB) Viewed 980 times
Bellhousing Dowel Bolt.jpg
Bellhousing Dowel Bolt.jpg (35.76 KiB) Viewed 980 times
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Re: Clutch Question

Post by twinflyer17 » Mon Mar 19, 2018 9:55 am

I wasn't aware of the bellhousing dowels. If these are added now to properly align the bellhousing, could it potentially help solve the current problem? Or is the bushing now too far worn, if alignment is part of the problem, and thus will need to be replaced regardless?
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Re: Clutch Question

Post by Joe Gopan » Mon Mar 19, 2018 11:40 am

Those two 630101 Clutch Housing Dowel Bolts get way too much credit. If one were to "mike" the 630101 Dowel Bolts and compare the diameter of the shoulder of a standard 3/8" NF X 2-1/2" Bolt of similar length to that of the 630101, it would be evident that the difference in diameter is too insignificant to affect the alignment of the housing.
Those two dowel bolts have probably been left out more than they have been reinstalled by unsuspecting Jeep "mechanics" for 75 years and all is still well. These dowels usually get their threads damaged by "mechanics" that are too eager with a hammer and get discarded with never knowing what they were. :wink:
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Re: Clutch Question

Post by twinflyer17 » Mon Mar 19, 2018 1:07 pm

Okay, thanks for the clarification on the benefits of the dowel bolts. I’ll consider the potential lack of those to not be the issue. Before suggesting, or helping, to tear thing apart, I’m still trying to better understand what the main issue here is. Seems like the general consensus is that the input shaft is potentially binding to the pilot bushing? Since this bushing doesn’t seem to be self lubricating, is there a way to apply grease or oil without pulling the tranny/engine?
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