Inner axle seal replacement

[rob love]

Just thought I would do a quick thread on a repair I am doing here at the RCA museum. One of the gun tractors sprouted a leak of gear oil at the knuckle, indicating the inner axle seal has, after only 70 years, had enough.

Luckily this one is a (uuugh) Chevrolet, so changing the axle seal is relatively easy. You just have to remove the complete knuckle at the flange on the axle. You will then see the poor old seal. I have not found a direct replacement, although I used to find a pretty close one back in the early 90s, but even then it was going obsolete.

The inner axle seals off the rockwell axles, as used on the M35 family of trucks (MLVW in Canada) have the right inside diamter, and come in a steel retainer that is unfortunately too large an outside diameter. The NSN for the M35 seal with retainer is 5330-00-075-1764 and they are readily available on the surplus market or on ebay.

I have included a photo of removing the knuckle using an electric pallet stacker. This worked out welll. You really don't want to be dragging the seal with the axle shaft. As well, the whole assembly is quite heavy. You may want to remove it in pieces, however as this is a rush job and I have the equipment it is being done this way.

Here is a shot of the tool you will need along with a slide hammer to remove the old seal. They are in there very tight.

Here is a shot of the old seal next to the MLVW seal and retainer. To make the MLVW seal work, you need to duct tape the seal and turn the retainer on a lathe to approx 3.620.

Here is a shot of the retainer and seal in place on the axle housing. Sealant has been applied to the outer edge to prevent oil from leaking past, although with the tightness it is not likely.

The axle shaft showed some wear at the original seal area The new seal moves the wear surface inwards so it will no longer be using the original wear surface.



Anyway, got to run. Time to install the knuckle and have it all together and brakes bled by this afternoon.

[rob love]

Got the job done today without issue.

Note that this was a Chevrolet Banjo axle. On a chev, the front axle uses these seals while the rear uses an outer wiper seal which is the same as a bren gun carrier.

Any Ford split axle uses these seals front and back. But to do them you have to remove the axle assemble and split the Banjo axle housing. Lots more work, and you really only want to do this work once. Quite frankly, it should be possible to simply use the Chev/UC Carrier rear wheel seal on the rear axle if you want to save yourself a very long day of heavy work. Also note that on a Ford the gasket on the differential halves is what sets the bearing preload for the differential, as well as the pinion to ring tooth pattern, so you need to use the proper thickness gasket, which is .006".

[Lynn Eades]

Interestingly Rob, when I was doing my carrier diff, the only reference I could find to the gasket thickness was in an Australian carrier parts book which stated 0.010" for the gasket. every thing else referred only to a part number.

[Andrew Rowe]

To get that preload on the Ford diffs, you may have to sometimes use a couple of thickness's of gaskets. It all depends on whether you are using new bearings, or re setting with old serviceable bearings, and also the condition of your housing. So there is no true rule as to the thickness you end up using, other than the sizes given are a good starting point for testing your preload. Also to check preload, do so with pinion out, just my experience.

[rob love]

It would make sense having different thicknesses to adjust for variables, but I have to say: What a pain in the ass. Certainly the RTV gasket glues aren`t going to do in this instance.