Help with rear axle/ differential rebuild

1941 - 1945, MB, GPW Technical questions and discussions, regarding anything related to the WWII jeep.
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ghiltgen
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Help with rear axle/ differential rebuild

Post by ghiltgen » Tue Jan 09, 2018 8:49 pm

I recently have been working on rebuilding my rear axle differential. I got to the point where I installed a new old stock ring and pinion and have sat a Pinion depth correctly and backlash correctly. I sacrificed a aftermarket Yoke by milling out the splines so I could slip it on and off to set the preload. Now that I’m trying to re-assemble everything the original Yoke does not fit on the Pinion. It won’t slide on enough to start the nut. I’ll try to upload a picture. Comparing the two it is not look like they are machined the same. For example the grooves on the original go down further compared to the new old stock. The new old stock is F scripted so it looks like it’s from World War II as advertised when I bought it . Should I Just purchase another aftermarket yoke and see if that fits?
A874E0D1-47FC-4EDA-BA53-FF46EB745EF5.jpeg
A874E0D1-47FC-4EDA-BA53-FF46EB745EF5.jpeg (104.14 KiB) Viewed 563 times
ghiltgen
1943 MB SN 226406
Veteran Award, Motorpool Class 2021
GPW 127386
1948 CJ2A
MVPA member 36543


Wolfman
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Re: Help with rear axle/ differential rebuild

Post by Wolfman » Wed Jan 10, 2018 6:02 am

Since you are making the final assembly, I have to assume ( there's that word ) that the front seal is already in place.
From the picture, it looks like the original pinion shaft spline goes almost all the way to the front bearing race position, where as the NOS spline stops well short of the front bearing position.
Can you see the front bearing position on the assembled NOS pinion shaft and is the spline well short of the front bearing inner race ??
If the spline on the pinion shaft does come up short of the race and the spline in the yoke goes all the way to the inner edge of the yoke, where the yoke meets the bearing race, you have a problem.
Don't hold me to this one. Visions of a lot of different yokes passing through the grey matter. But I am thinking, some yokes have the spline counter sunk on the inner end. ????
If the yoke spline is counter sunk, it would be a matter of measuring the distance from the front of the front bearing inner race to the spline on the pinion shaft and then comparing that distance to how deep the yoke is counter sunk.
If not counter sunk, go back to what I said before I came up with the counter sunk idea.
Could be what Luc said. Yoke is tight on the pinion spline.
Keep us updated.
Mike Wolford
CJ-2A
VEP GPW
Comm./Inst. SEL
AOPA ( 50 yrs)
EAA ( 49 yrs)
4th Inf. Div. - 5th Inf. Div. - 2nd Armor Div. - CIB

pittsjock
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Re: Help with rear axle/ differential rebuild

Post by pittsjock » Thu Jan 11, 2018 4:11 am

I think Mike might be right about the splines being "recessed" in some yolks.

That being said, it looks like the difference in groove depth between original and NOS is less than 3/8 of an inch. It may be enough to prevent you from fully seating the yolk, but it doesn't look like it is enough to stop you from starting the nut. I am betting you don't have the front bearing fully seated. I had to abuse a large socket to drive the outer bearing on enough for the nut to start.

Patrick
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ghiltgen
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Re: Help with rear axle/ differential rebuild

Post by ghiltgen » Thu Jan 11, 2018 8:04 am

I ended up looking closer at the yoke. It was clean and degreased but there were a few nicks and raised areas that I gently dressed down with a file. Then I looked closer athe areas in between the spline and saw traces of cosmolene which I then cleaned out. Then I polished the spine and inter spline areas with 400 grit sand paper then washed all the dust off; and finally success! I was so excited to get it put together that I missed some of the basic stuff. It was helpful knowing that it should work and no one is reporting trouble with NOS parts. I had a T84 aftermarket input shaft that was machine incorrectly so when I saw the difference in machining on these pin ions I panicked.
The biggest problem I had was that used set up bearings for the carrier which had the ID enlarged slightly so I could easily get them on and off to get the shims right, but when I pressed on the new bearing using a large socket the bearings didn't seat all the way down so the carrier would got in! So I pulled the bearings and placed new shims then I figured out the problem and ended up using a 1 1/2 plumbing pipe cap to get the bearing down all the way. Now all is well and I finished my first rear differential.
Thank to all!
ghiltgen
1943 MB SN 226406
Veteran Award, Motorpool Class 2021
GPW 127386
1948 CJ2A
MVPA member 36543

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ghiltgen
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Re: Help with rear axle/ differential rebuild

Post by ghiltgen » Thu Jan 11, 2018 8:10 am

Final result
Attachments
2041CCD1-4E88-4533-A194-BE28D21C3E04.jpeg
2041CCD1-4E88-4533-A194-BE28D21C3E04.jpeg (128.5 KiB) Viewed 490 times
ghiltgen
1943 MB SN 226406
Veteran Award, Motorpool Class 2021
GPW 127386
1948 CJ2A
MVPA member 36543

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Boyso
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Re: Help with rear axle/ differential rebuild

Post by Boyso » Thu Jan 11, 2018 9:00 am

Looking sharp!
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Wolfman
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Re: Help with rear axle/ differential rebuild

Post by Wolfman » Fri Jan 12, 2018 5:02 am

Outstanding !
I love a happy ending !!
Mike Wolford
CJ-2A
VEP GPW
Comm./Inst. SEL
AOPA ( 50 yrs)
EAA ( 49 yrs)
4th Inf. Div. - 5th Inf. Div. - 2nd Armor Div. - CIB

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ghiltgen
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Re: Help with rear axle/ differential rebuild

Post by ghiltgen » Sat Jan 20, 2018 7:42 pm

Thanks, yes I did recheck tooth pattern after new bearing were in!
ghiltgen
1943 MB SN 226406
Veteran Award, Motorpool Class 2021
GPW 127386
1948 CJ2A
MVPA member 36543

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ghiltgen
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Re: Help with rear axle/ differential rebuild

Post by ghiltgen » Fri Jan 26, 2018 6:21 pm

Ok Ill work on a summary of how I did it and try to post it.
ghiltgen
1943 MB SN 226406
Veteran Award, Motorpool Class 2021
GPW 127386
1948 CJ2A
MVPA member 36543


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