G-506 Chev. rear axle outer lock nut w/seal.

[forestry4evr]

On Saturday, I removed the rear axle shafts on my 42 g506. I am perplexed on the rear outer seal issue. The seal surface area on the axle shaft is a smaller diameter than the inside diameter of the outer lock nut seal. This seal cannot serve any purpose! Also, the rear wheel bearings have no residue of grease, only wet with gear oil. The civilian shop manual makes no mention of an outer seal. In the bearing portion, the manual says to “pack the roller assembly with No. 2 ½ soft smooth cup grease”. Why pack a bearing with grease that is going to be washed by gear oil?

http://chevy.oldcarmanualproject.com/sh ... csm096.htm

The military manual shows the seal, and refers to the seal fit on the axle shaft. It also calls for repacking the bearings with a No. 2 grease.

http://chevy.oldcarmanualproject.com/mi ... mt1305.htm

I did not have a caliper at the time, but I would estimate that the difference between the axle shaft diameter is ~1/8 of an inch smaller than the ID of the seal. Something does not add up?

[Ben Dover]

You may have an aftermarket axleshaft that is incorrectly made. There were a few hundred thousand Banjo GMC and Chev 4X4 trucks with the same bearings and seals, they worked just fine. Can you post a pic of the inside and outside of the Axle Flange of the problem axle. I believe the problem is with that particular axle, the correct ones are machined flat on the inside of the flange. You may have to buy another axle shaft.
Look at your manual agan, I'll bet it indicates #2 Wheel Bearing Grease, you should consult a later dated G-506 manual and you will find that the the Wheel Bearing Grease is listed differently. Best to use a modern Wheel Bearing Grease that is available at your local parts house. I use GI Issue GAA on all my MV's and suggest it to those that can find it. I have a 16 gallon Barrel and have not had to look for a while. There is a gentleman in New York or PA that sells it in Gallon Pails and in the Cartridges. I do not have his address.

NOTE:
You do realize that the seal on the Lock Nut is stationary and is compressed against the machined inner face of the axle flange, don't you? Proper sealing is accomplished with proper wheel bearing adjustment, which then ensures the GO-90 stays within the axle housing.

[Sgt. Hancock]

You must have the correct washers that fit in conjunction with the spindle lock nuts. One is flat with a tooth in the I.D. that engages the notch in the spindle, and the other is a 'spider' type that also has a tooth and 'legs' that lock into the outer spindle nut/seal assy. to hold it from backing off the spindle during the operation of the truck.
If you do not have these washers, the space between the nut/seal assy. and the inside of the axle flange will be too great. This will allow the gear oil to splash into the wheel bearings and wash the bearing grease away.

[forestry4evr]

First of all, thanks for the support on what seems like an eternal G506 issue.

I suppose this explanation would be best done with photographs. Unfortunately I was too greasy to take the camera out. I will take some images this weekend.

Is the outer seal supposed to seal against the axle flange or the axle shaft? Intuitively I would imagine the shaft. If it is the flange surface, perhaps all is well.

Both trucks have the right hub/bearing parts described in the parts manual, so the distance of the outer seal should be correct. I would find it improbable to have (4) axle shafts that are machined incorrectly, unless they are all civilian and are machined differently than military. Does anyone have a part number comparison of military/civilian axle shafts?

From the civilian manual, how do the bearings keep from washing out the grease without an outer axle seal as in the military version? The principles of construction look the same.

Thanks,

Paul

[Ben Dover]

The only axle shafts that fit the G-506 are those that are made specifically for it, it does not share rear axle shafts with any other GM Truck. They are length and spline specific and very hard to find. Foote Axle was the last manufacturer and NOS GI stock is virtually non existant. The only way to keep the Gear Oil contained in the axle housings and not in contact with the Wheel bearing Grease is by installation of te outer wheel bearing nut with the seal on it. Some other Civilian Chevy trucks with floating axles may indeed allow circulation of the GO to lubricate the wheel bearings, the G-506 is not one of them.

[forestry4evr]

I will look at the seal, mating surface more closely. If the seal is supposed to contact the axle flange surface, I think everything is good.

Sgt. Hancock, you had mentioned a "slick" way to remove/replace that outer seal. Can you share your technique?

[Sgt. Hancock]

What I did was to chuck the spindle nut/seal assy. up in my vice. *Don't lean on the vice handle too hard, you don't want a oval spindle nut when you are finished*. I took an old wood chisel and ground it down so the blade was the same width as the groove in the nut. I also ground the edge so the blade was sharp. I then went to work cutting the old seal out. This is an exercise of FINESSE not brute force. Even though you won't hurt the nut, you don't want to be chasing it across the garage floor after every swing of the hammer.
After the seal had been successfully removed, I used the correct 6 point castle socket for the installation of the nut/seal assy. onto the spindle, to press everything back together. I inserted the seal into the socket, lined up the nut with the seal and socket. I then put everything down vertically on my work bench, (nut/seal down), and protected the top end of the socket with a short length of 2x4 wood. I then bumped everything together with a 4 pound sledge hammer. Again practicing finesse so I don't risk damaging the seal. Make sure you line the nut and seal up correctly because once the seal is in, it's in. I destroyed a seal with my first attempt at this.
The whole process took around 10 minutes for each assy. after I got the hang of it. I bought 20 seals and rebuilt 14 nuts for myself and some friends.

[forestry4evr]

Thanks for the tip. I will be replacing the seal in the very near future.

[Sgt. Hancock]

You're welcome.