Inner Axle Seal Part Number and Replacement

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RBW
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Inner Axle Seal Part Number and Replacement

Post by RBW » Mon Nov 01, 2021 7:43 pm

Hello

I'm new to the forum and working on getting an M274A4 Mule running again. Filled the transmission with gear oil and found that it was filling the right drop axle housing, so I suspect the inner oil seal has gone bad. This is mentioned in another posting.

I understand the seal I need is P/N 7966768, which is listed in the parts catalog as NSN 2520-697-4286. I believe this updates to NSN 5330-00-697-4286. Does anyone have a part number for a commercially available seal that will work in this application?

Also, I saw mention of a previous post that discussed replacing this seal. I understand it's a bit of a chore to access. Does anyone have a link to a post that addresses this, or a summary of how you accomplished this repair?

Thanks for any help.


Curtis


Chuck W.
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Re: Inner Axle Seal Part Number and Replacement

Post by Chuck W. » Tue Nov 02, 2021 9:27 am

I would suggest that you get the seals from John Emery, he has quality, fresh, double-lip seals that work great. Here's a link to some work I did a while back that might help. Make sure you study the TM so you know how to set the bearing clearance.
viewtopic.php?f=79&t=324343

and this one:
viewtopic.php?f=79&t=319455&p=1860735#p1859955

RBW
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Re: Inner Axle Seal Part Number and Replacement

Post by RBW » Tue Nov 02, 2021 1:54 pm

Chuck,

Thank you. I'll get in contact with John Emery.

Regards,

Curtis

RBW
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Re: Inner Axle Seal Part Number and Replacement

Post by RBW » Sat Nov 06, 2021 4:55 pm

I guess I do have another question on this one. After reading TM 9-2320-246-34, I'm inferring that the bearing clearance has to be checked because the drop housing is disassembled and the gasket being reseated affects the bearing clearance for the helical driven gear. Is this correct? It looks like the relationship among the components of the upper axle shaft remains relatively fixed as they are held in place using retaining rings. Thanks.

Curtis

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Re: Inner Axle Seal Part Number and Replacement

Post by RBW » Thu Nov 11, 2021 4:50 am

Got in contact with John Emery - very impressed and appreciative of his helpfulness and knowledge. Will get everything figured out.

Curtis

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Re: Inner Axle Seal Part Number and Replacement

Post by Chuck W. » Sun Nov 14, 2021 6:11 am

I guess I do have another question on this one. After reading TM 9-2320-246-34, I'm inferring that the bearing clearance has to be checked because the drop housing is disassembled and the gasket being reseated affects the bearing clearance for the helical driven gear. Is this correct? It looks like the relationship among the components of the upper axle shaft remains relatively fixed as they are held in place using retaining rings. Thanks.
Basically, yes. If you don't change the cups and cones on the helical driven gear, you will probably be OK, but I'd still recommend that you check it, and make sure you have the gasket in place when you check the clearance.
Image

No adjustment to the needle bearings, but make sure they are installed deep enough to clear the lubrication notches in the housing.
Image

RBW
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Re: Inner Axle Seal Part Number and Replacement

Post by RBW » Sun Dec 12, 2021 5:37 am

Update on this issue - I pulled the right rear drop axle housing and retaining clip for the upper input shaft bearing. The old oil seal (upper seal just inboard of the input shaft bearing accessible from the drop axle housing) was completely mangled and dislodged from its bore, and came out with the shaft. Minimal wear to the gears, so I think it's not a high time machine, but there are some areas of heavy pitting due to water intrusion. I dressed up the bearing and oil seal journal on the upper shaft, polished it, pressed the new seal in, and it doesn't leak! I was having trouble figuring out how the transmission oil was draining so quickly into the drop axle housing - almost as quickly as I was filling it. Dislodged oil seal makes sense now. I drained 20 oz of gear lube out of the right rear drop axle housing and 28 oz out of the transmission. Also, I could not get the right rear steering knuckle dust boot to stop leaking. It seems that once the oil level gets above about mid-level on the output shaft, the dust boot will start to leak. It also seems the hydraulic pressure created by rotating the knuckle with the steering wheel, or maybe the extra lubricity of all that gear oil, causes the boot to more easily separate from its recess in the drop axle cover, so I was getting gear oil everywhere. It's much better now so far. I checked the gear backlash through the drop axle oil plug, and checked the end play/output gear tapered roller bearing preload through the drop axle cover opening. Everything in order with the new gasket, so I reassembled and ran it. Now that the machine is running, I'm getting a little gear oil inside the bell housing, so I'll have to address that and install the new clutch cable.

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Re: Inner Axle Seal Part Number and Replacement

Post by Chuck W. » Sun Dec 12, 2021 7:31 am

That's great, but if you are getting oil in the bell housing, it's 99.9% chance that it's coming from the left axle inner seal, which is actually on the right side, behind the ring gear.
Image
This seal goes in from the right side, which means you will have to tear the right side back down, remove the right axle housing and ring gear to get at it.
Image
It's not too bad of a job as long as the frame tube-to-axle housing bolts will come loose.
Image
Good luck with your project, let me know if I can help!

RBW
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Re: Inner Axle Seal Part Number and Replacement

Post by RBW » Mon Dec 13, 2021 4:18 pm

Thanks for the pictures - that helps to get an idea of the scope of the job. I have a dental camera that I'm going to try to use to get a view of the left pinion housing seal.There's no other access to this seal other than removing the six bolts and pulling the right axle housing, correct? Fortunately, all the axle-to-frame tube bolts are free. I only had one hard stuck at the front left that I had to surgically drill in order to remove.

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Re: Inner Axle Seal Part Number and Replacement

Post by Chuck W. » Sat Dec 18, 2021 6:58 pm

There's no other access to this seal other than removing the six bolts and pulling the right axle housing, correct?
That's correct. You can see the seal from the bellhousing side, but it's installed from the ring gear side.


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