Front differential problems

1959 - 1978, M151, M151A1, M151A2, Technical questions and discussions, regarding anything related to the M151.
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Gary Turman
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Front differential problems

Post by Gary Turman » Sun Aug 06, 2017 8:43 am

When I go to put my A1 in four wheel drive it's very difficult to get back out. While in four wheel drive it knocks and is jerky. Any suggestions before I tear it apart?
1941 Dodge WC-7 Command Car
1942 Ford GPW
1954 Willys M38-A1
1968 M151-A1
1952 Strick M100
1967 M416
1945 Gemco 1/4 ton trailer

Fil Bonica
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Re: Front differential problems

Post by Fil Bonica » Sun Aug 06, 2017 11:16 am

Never engage, disengage or drive on hard surfaces with jeep in four wheel drive.
What you describe is typical of what happens.

Fil Bonica

Gary Turman
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Re: Front differential problems

Post by Gary Turman » Sun Aug 06, 2017 12:52 pm

I was climbing a dirt hill and lost traction so I put in four wheel drive that's when I experienced the problem. It worked but made a lot of noise then was very difficult to disengage. I have experienced this since I got it several years ago but now and determined to fix it. I don't use 4x4 on hard surfaces, maybe the previous owner did I don't know.
1941 Dodge WC-7 Command Car
1942 Ford GPW
1954 Willys M38-A1
1968 M151-A1
1952 Strick M100
1967 M416
1945 Gemco 1/4 ton trailer

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muttguru
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Re: Front differential problems

Post by muttguru » Sun Aug 06, 2017 1:30 pm

Gary....what Fil just said. Using 4wd on hard-surfaces can cause "torsional wind-up". If one of the wheels can't "slip" a little to compensate for slight turns, the whole driveline winds up. The quick cure is to either reverse a little or to jack up one wheel to allow the windup to ease.

If you already are aware of all that......then it could be that your front drive is excessively worn. The most likely culprits are any one (or more) of the six u-joints on the front end. If they haven't been lubed as often as they should, or have worn, then you will get clicking and chirping noises.

Here's what I would do to make a preliminary check.
1. Put the vehicle into 4wd with the gearshift in first gear.
2. Turn the engine off.
3. Chock the rear wheels so it can't roll back OR forward.
4. Release the parking brake.
5. Securely raise the front end of the vehicle so that the front wheels are off the ground.
6. Get a friend to turn one front wheel while you inspect each of the two u-joints on that front wheel shaft.
7. Look closely at the u-joint using a flashlight as your colleague rotates the wheel back and forth. Check for play, clicking, rattling etc.
8. Now repeat that exercise on the other front wheel.
9. Now check the two u-joints on the front propellor shaft.
10. If there's any sign of play in any one of those six joints, start thinking about replacing them with new.
Ken
Kind Regards, Ken muttguru@aol.com
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Never mind..."I think it's ok"...Check it again !

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muttguru
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Re: Front differential problems

Post by muttguru » Sun Aug 06, 2017 1:37 pm

ps.... I presume the oil level in the front differential (and your transmission) is correct and that the oil is reasonably good? The front diff on the M151-series usually has a fairly comfortable life compared to the rear one. The rear is always under load but the front diff normally only coasts along.....so front diffs are generally in better condition than the rears. However, it's always possible that a previous owner has swapped the diffs front-to-rear because the rear diff was giving problems. You could have inherited a vehicle that has had the diffs switched around.
Ken
Kind Regards, Ken muttguru@aol.com
Resolutions for 2013...
Never mind..."I think it's ok"...Check it again !


Gary Turman
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Re: Front differential problems

Post by Gary Turman » Sun Aug 06, 2017 9:39 pm

Thanks Ken, I have all day tomorrow and will look into what you told me...thanks again. I will post the results
1941 Dodge WC-7 Command Car
1942 Ford GPW
1954 Willys M38-A1
1968 M151-A1
1952 Strick M100
1967 M416
1945 Gemco 1/4 ton trailer

Rickf
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Re: Front differential problems

Post by Rickf » Mon Aug 07, 2017 6:48 am

If the u-joints look good then drain the oil from the differential into a clean container and see if there is any metal in it. Check the magnet on the drain plug for metal. If there is any metal the issue is probably inside the differential, possibly as broken spider gear. If all looks good there I would do the same with the transmission/transfer case.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

Walter
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Re: Front differential problems

Post by Walter » Tue Aug 08, 2017 7:51 pm

Good Evening Everyone:
I am not sure what the collective experiences with the differentials on the M-151A1 have been, but a long time ago I spent a good bit of time under those criters replacing the differentials. I was assigned to two units in the Air Force in the 1970's that between the two had either the straight M-151A1, the MRC 107/108 FAC radio versions of that jeep or the M718 field ambulance. We had considerable problems with the differentials. We always kept a couple of them hidden as it seemed that we were always changing them. Mutt Guru could be right about someone swapping them front to back. They are relatively simple to change. My suggestion would be to keep an extra one around, to keep the rig "Mission/Parade ready" and on the road.

Hope that helps.

Regards,

Walter

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