The Transmission of Woe - Cont’d from “Sluggish Differential”

1959 - 1978, M151, M151A1, M151A2, Technical questions and discussions, regarding anything related to the M151.
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Crux444
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The Transmission of Woe - Cont’d from “Sluggish Differential”

Post by Crux444 » Sun Oct 30, 2022 2:54 pm

Starting a nee topic to continue from my earlier “Sluggish Differential” post earlier.

So Rickf suggested the transmission was dodgy in his last post on the subject. I thought it could be the main seal on the engine which was leaking oil into the flywheel housing and that it had gotten on the flywheel and soaked into the clutch disc. This could have caused the clutch to slip (in my addled mind, anyway).

Not so. Pulled the engine today and the flywheel was bone dry, so Rickf’s comment that it could be transmission fluid, certainly was correct as the gaskets were wet between the flywheel housing and transmission. But that’s not the real problem…. Recall in my last post, I commented that the transfer case wouldn’t engage 4WD, so today was planned to be transmission tear down day.

Expecting to see golden transmission fluid when I pulled the drain plug, I was sickened to see it looked like thick gunmetal coloured paint. 🤢 Removing the shift cover I could see silver-grey sludge in the bottom of the sump, and the drain plug magnet was stacked with chips in sludge. Now I know there is a real problem, so try to remove the transfer case so I can then get the gears and shafts out of the transmission.

But here’s the problem: The transfer case slides forward 1/2” and stops fast. It looks like the shaft to the forward flange is jammed fast into the rear flange gear and preventing the transfer case and transmission from separating. I can’t get any leverage to get it off.

Has anyone experienced something similar? I was thinking that worst case I could cut the shaft, but it’s probably case hardened and a hacksaw blade would only mar it. I’d rather replace a shaft or two vs. Buying a refurb transmission for $1,500.

Any insight is welcome.

Thanks,
Sean
Canadian Army (1988-2011)
Kandahar, Afghanistan 2006-2007

M151A2 CDN (1974)


Rickf
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Re: The Transmission of Woe - Cont’d from “Sluggish Differential”

Post by Rickf » Sun Oct 30, 2022 5:43 pm

Sean, this is where I am going to refer you to the manual. Trying to explain a complete tranny teardown can be complicated in person but on the internet with probably 4-5 other people all vying to have Their idea be the one that fixes it then it gets doubly complicated. So your best bet here is to go to the -20 and -34 manuals and read through the transmission sections. This will give you the info you need to get this apart without damage. Or further damage. If Horst reads this he may chime in since I believe he just had his apart a week or so ago but I would actually go into the manual myself before offering advice since I always want to be sure of what I am saying. That is why the manuals are there. Never be too proud to get the book (or computer) out!
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

Crux444
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Joined: Tue Mar 23, 2021 4:15 am
Location: Burlington, ON, Canada

Re: The Transmission of Woe - Cont’d from “Sluggish Differential”

Post by Crux444 » Mon Oct 31, 2022 10:46 am

Rickf, I have both manuals and have read the sections on tranny/xfer case extensively. The “soldier-proof” manuals are a Godsend, and I follow them to the letter any time I turn a screw.

When I was troubleshooting the 4WD shift problem, I noticed that the front output shaft was turning with and without the xfer case lever engaged. This leads me to believe that the forward and rear output shafts didn’t mesh properly and the spline is jammed into the other (like cross-threading a nut on a bolt).

TM 9-2320-218-34-1 (Aug. 1982 version) shows the transfer case removal on p.7-17, steps 13-14. What should be the case of removing 8 bolts and separating the teo components can’t occur because it feels like those two lower output shafts are jammed preventing the separation.

TM 9-2320-218-34-1 parts manual (Nov.. 1988) p.69-2 shows part #s 30, 31 and 37 which I think are the problem. I am thinking about using a gear puller to remove the retainer roller (part 28) on the rear output shaft to give me access to remove the retaining rings and bearing assembly (part 25) which should allow for separation of the xfer case from the tranny. That will allow me to get into the lower tranny to understand what the source of the 4WD issue and cause of the goopy transmission fluid. Process of elimination.

Please advise if you think the approach is sheet madness ir fraught with unseen perils.

☺️
Canadian Army (1988-2011)
Kandahar, Afghanistan 2006-2007

M151A2 CDN (1974)

Rickf
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Re: The Transmission of Woe - Cont’d from “Sluggish Differential”

Post by Rickf » Mon Oct 31, 2022 1:21 pm

Ok, I just came in from modifying an old engine hoist into a three point hitch hoist for the back of my tractor. Lots of cutting, welding and CAD ( cardboard assisted design ). My back is killing me so I need to sit and unwind for a bit and then I will look at the manual. When the transfer case went back together are you sure the transfer shift fork was engaged properly? Sounds like it was off the collar and jammed in front of the slider and holding it in 4 wheel drive. I will look through the book and get back to you, may not be tonight, may be tomorrow.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

Crux444
G-Staff Sergeant
G-Staff Sergeant
Posts: 51
Joined: Tue Mar 23, 2021 4:15 am
Location: Burlington, ON, Canada

Re: The Transmission of Woe - Cont’d from “Sluggish Differential”

Post by Crux444 » Mon Oct 31, 2022 2:52 pm

The last time I disassembled the transmission I did NOT remove the transfer case shift fork assembly, or remove the lower output shaft, so it likely isn’t that, but Ive been wrong before… 😉

Appreciate the help. Enjoy a frosty adult beverage. Look forward to hearing from you when you find some time.

Thanks!
Canadian Army (1988-2011)
Kandahar, Afghanistan 2006-2007

M151A2 CDN (1974)

Rickf
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Re: The Transmission of Woe - Cont’d from “Sluggish Differential”

Post by Rickf » Tue Nov 01, 2022 10:58 am

Check your PM's.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

Crux444
G-Staff Sergeant
G-Staff Sergeant
Posts: 51
Joined: Tue Mar 23, 2021 4:15 am
Location: Burlington, ON, Canada

Re: The Transmission of Woe - Cont’d from “Sluggish Differential”

Post by Crux444 » Sun Nov 06, 2022 8:24 am

Thanks to Rick for helping troubleshoot over a phone call. After a full disassembly of the transmission, two issues were discovered:

1) The rear roller bearing race in the intermediate gear of the transfer case had fractured, sending pieces into the transmission and chipping several teeth on the main gear cluster. This was the cause if the significant amount of metal ships and powder in the transmission fluid.

2) there was a ball bearing loose in the transmission that I couldn’t place. I removed all bearings to inspect for damage and if the ball was from any of them; all bearings were intact, but were crunchy with metal flakes from the race/gear issue. The transfer gear shifter kit comes with a ball bearing - while I can’t see that in the -34P manual, my thought is that it came loose and somehow impeded the clutch from engaging the forward output shaft. This would have been why I couldn’t engage into 4WD.

I am replacing all bearings throughout, as well as a new cluster gear, and transfer repair kit which should arrive this week. Will advise how things go.

Cheers, all!
Canadian Army (1988-2011)
Kandahar, Afghanistan 2006-2007

M151A2 CDN (1974)

Rickf
G-Lieutenant General
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Posts: 5911
Joined: Sun Mar 19, 2006 10:04 am
Location: Pemberton, New Jersey

Re: The Transmission of Woe - Cont’d from “Sluggish Differential”

Post by Rickf » Sun Nov 06, 2022 10:15 am

Great update, At least great as far as letting us know what you found. Do you think this was a case of loose parts left behind from previous rebuild? I have never seen a roller bearing race fracture from use, or even abuse.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

Crux444
G-Staff Sergeant
G-Staff Sergeant
Posts: 51
Joined: Tue Mar 23, 2021 4:15 am
Location: Burlington, ON, Canada

Re: The Transmission of Woe - Cont’d from “Sluggish Differential”

Post by Crux444 » Mon Nov 07, 2022 9:29 am

Rick, it definitely wasn’t a result of parts left loose from a previous rebuild. The last time I pulled the transmission it was to replace the 3-4 gear cluster; I didn’t touch the transfer case shift fork/clutch assembly, and it did shift to 4WD in the post-restoration shakedown drive.

Also, the bearing race was intact when the transfer case went back on. Some things in life are mysteries, like why do we drive on a parkway, but park in a driveway…?
Canadian Army (1988-2011)
Kandahar, Afghanistan 2006-2007

M151A2 CDN (1974)


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