Rear axle- excessive bearing end play

1945 - 196*, Willys CJ series, questions, discussions, regarding anything related to the post war jeep.®
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wc56daveyboy
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Rear axle- excessive bearing end play

Post by wc56daveyboy » Thu Jul 23, 2020 4:59 pm

I posted this on the M-38 technical page too but realized the 3A has this tapered axle shaft too and by posting here maybe I’ll reach a broader group that might have answers

Anyway... So I’m rebuilding the rear axle on my 51 m38.
After completely disassembling the rear, degreasing and cleaning, I’m putting it all back together

Started with the drivers side (long axle)

I’m noticing excessive end play after re-seating the bearing race. If I seat the bearing race flush with the outer axle flange, as per videos I’m watching, I can pull the axle back and forth (in and out) a good 1/8”

Now I know this isn’t right.

Now I went one step further and can actually tap the race in a bit further (deeper than flush) and the shaft is now tight

But that’s not right. In operation this race is going to work itself back out to flush with the outer axle flange

So what’s going on here? Is the bearing rollers so worn they are allowing this movement?
Do I need new rear axle bearings?

Or is there an inner shim to keep that race in deeper?
Though as I say this I’m sure it would work but isn’t the right answer

One thing.. when I pulled out the axle shaft, the bearing fell apart. Meaning the tapered rollers fell out of the cage. I’m easily able to put it all back together with grease and it all goes in fine and turns nicely. The race is clean and burr and rust free. So are the rollers.

Are these bearing supposed to come apart and be rebuilt as I described? Or no,

Anyway. I found this video on You-tube.
It’s exactly what I’m experiencing.

https://www.youtube.com/watch?v=fGOs-198hvU


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Re: Rear axle- excessive bearing end play

Post by Rus Curtis » Fri Jul 24, 2020 7:34 am

Daveboy,
First thing on the bearings.
wc56daveyboy wrote:One thing.. when I pulled out the axle shaft, the bearing fell apart. Meaning the tapered rollers fell out of the cage. I’m easily able to put it all back together with grease and it all goes in fine and turns nicely. The race is clean and burr and rust free. So are the rollers.

Are these bearing supposed to come apart and be rebuilt as I described? Or no,

I would not re-use a bearing that fell apart. I would absolutely replace (both sides to keep them matched).

I'm assuming you have a Dana41 (shouldn't matter since you describe as tapered).
After completely disassembling the rear, degreasing and cleaning, I’m putting it all back together...Started with the drivers side (long axle)
I’m noticing excessive end play after re-seating the bearing race. If I seat the bearing race flush with the outer axle flange, as per videos I’m watching, I can pull the axle back and forth (in and out) a good 1/8”.....So what’s going on here? Is the bearing rollers so worn they are allowing this movement?
The bearings should not be trusted. I would replace both sides. If you have both axle shafts removed, you cannot set end play with only one axle shaft. It's done together as a unit. Since the other side has been disassembled, replace that bearing also - so that both sides match (remember to replace the seals too!). Shims can be placed on both sides or only on one side to set the end play - when you disassembled, didn't you have shims that came off?
Do I need new rear axle bearings?......Or is there an inner shim to keep that race in deeper?
Yes - replace the bearings. There is a part inside the differential that plays a part with setting end play. It's called a Spacer or Center Block and sits in the middle of the Case Gears (Spider Gears). With the differential cover off, look and see if it's there in between the axle ends. The Case Pinion Shaft goes through this Spacer in an oval shaped hole (this is so it can move back and forth between the axles). Could you have rotated it 90 degrees so that it can't make contact with the ends of the axle shafts?

Both bearing cups once installed (NOT flush with the axle housing flange) sticking out slightly, you can add shims (more gives you more end play) and then the bearings can be drawn in using the Bearing Retainer. Sometimes you have to measure more than once as you are adding/subtracting shims. One technique to setting end play is to mount one axle flush (with retainer bolted on) then use the shims on the opposite side to measure for end play. Shims can be put on only one side (I divided mine so that each side has some of the shims).

Posts from the CJ2A Forum:
https://www.thecj2apage.com/forums/dana ... lay#469731
https://www.thecj2apage.com/forums/tape ... lay#458189

HTH
Rus Curtis
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Re: Rear axle- excessive bearing end play

Post by wc56daveyboy » Fri Jul 24, 2020 7:59 am

Thank you Russ.

I’m going to order new bearings and races, both sides, and a shim set.

I see the bearings get pressed on the shaft.

I guess I’ll wait till parts arrive and have a local machine shop press off remains of old bearing race and press on the new bearing assembly.

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Re: Rear axle- excessive bearing end play

Post by Rus Curtis » Fri Jul 24, 2020 8:06 am

That's what I did. Machine shop makes it easy.

did you have the spacer block in place inside the differential case?
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Re: Rear axle- excessive bearing end play

Post by wc56daveyboy » Fri Jul 24, 2020 8:46 am

did you have the spacer block in place inside the differential case?
Ya know I didn’t realize this part existed and honestly didnt look for it when I had the rear diff
Cover off to clean and inspect the R&P.

I’m gonna assume it’s there as it’s all buttoned you now

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Re: Rear axle- excessive bearing end play

Post by Rus Curtis » Fri Jul 24, 2020 9:06 am

Okay, but......

I'm not 100% sure but that little spacer block may have enough room to spin off where it needs to be when inserting axles to hit up against it. Fingers crossed I'm wrong or that it's positioned correctly.


I think that when you insert the axle shafts you still can't get the end play set, it will be that spacer block. Good luck.
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Re: Rear axle- excessive bearing end play

Post by wc56daveyboy » Fri Jul 24, 2020 5:21 pm

I’ll keep that in mind, Rus. Thanks for the heads up!

So can that spacer block fall out by chance?

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Re: Rear axle- excessive bearing end play

Post by Rus Curtis » Fri Jul 24, 2020 6:51 pm

I'm real glad I went back and looked at my photos.

Image

Here's a look at the case/gears. The spacer block is the one with the oval hole in it. The pinion shaft goes through that hole ( you can see the ends of that shaft on the outer edge of the case). As you can see, the intent is for the spacer to "float" between the axle ends - hence the oval hole.

Funny how you can forget how tight something is working off just memory. Short answer to your question is no, it can't fall out (assuming all other parts are in place and serviceable). Secondly, I don't see how it could rotate in place either - unless there was a lot of movement on those gears. So I was wrong on that idea.

But, if after getting the good bearings on, and you can still get both axle shafts to move inward to flush on the bearing cups, I'd suggest looking inside the diff.
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Re: Rear axle- excessive bearing end play

Post by Joe Gopan » Sat Jul 25, 2020 3:11 am

Buy new Bearings, a shim Kit (648195) get a parts manual and service manual (never go into the unknown without the manuals) and carefully lubricate the rear bearings every 12,000 Miles per the Lube Chart. Grease it too often and it can blow past the outer seals and ruin brake shoes.
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Re: Rear axle- excessive bearing end play

Post by Joe Gopan » Sat Jul 25, 2020 8:58 am

The CJ-3A can have either a Spicer 41 or Spicer 44 depending if it is an early or late CJ-3A. The Spicer 41 and Spicer 44 share the same Axle Shafts and Oil or Grease Seals, the difference is in thr differential housing. Notr the Round #41 and Oval #44. Did you install a new Axle Seal, it goes the housing and the inner race has to be removed before it can be removed or installed, the Outer Axle seal is located at the outer face of the backing plates. If the inner seal is bad, Oil will run out past the outer seal onto your brakes. The condition of the bearing indicates the inner seal is NG.. Installing the axle seals and bearings on the Spicer 41 or 44 can be a touchy job for those who are new to the task. A lot of special shop tools are required that the do it your self mechanic may not have.
2011 MVPA PIONEER AWARD - MVPA #1064
HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
LIFE MEMBER AM LEGION-40/8-DAV
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Re: Rear axle- excessive bearing end play

Post by Joe Gopan » Sat Jul 25, 2020 11:54 am

Be careful installing the hub, if the key is installed wrong end to, or without paying attention to the taper on the shaft, it will distort or crack the key way ( seal surface ) on the hub.
2011 MVPA PIONEER AWARD - MVPA #1064
HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
LIFE MEMBER AM LEGION-40/8-DAV
7 MIL SPEC MAINTAINED MV'S
COL. BRUNO BROOKS (ARMY MOTORS) IS MY HERO

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Re: Rear axle- excessive bearing end play

Post by wc56daveyboy » Sat Jul 25, 2020 5:33 pm

Thanks Joel, for your insight on this.

My Jeep is an M38. Has a dana 44.

Yup. Everything was taken apart and cleaned. Yes. New inner housing axle seals were installed.
And once I get the new bearings, the outer seals ready to go in..

Yup. Reading past posts from you I’ve read the orientation of the key in the keyway importance. Thanks for that.

I’m trying to do this jeep 100% as I’ve wanted an M38 for a long time and this one being so rust free is gonna be my “keeper”!

Thank you again for your knowledge base. Always welcomed


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