The Stovebolt Site Forums The Shop Area Driveline Dripping rearend mount

A few years back, I changed out the leaf spring bushings on all four corners of my '46 1/2 ton. In the last year, grease has begun dripping out in mass quantities on the right rear end mount as you can see in the pictures. What would cause this? Is there some sort of part or reservoir that should be in there to hold the grease? Why would it drip out? It is not a leaking wheel cylinder or wheel seal. It drips directly down from the mounting bolts with no path connecting it to the backing plate or wheel. I hope I explained the issue and the pictures below should help. Any help is appreciated.

Big T

Pic 1

Pic 2

Pic 3

Big T,
Same thing was happening on my '37 Chevy half ton project when I got it. That is gear oil from the differential/axle. As you probably know, the rear axle bearings are lubricated by the differential gear oil that sloshes down the axle tube. The rear axle housing rotates on the brackets that hold the axle to the springs, that is why you have a grease fitting, seen in your first picture. Those brackets have an internal slot machined in them where a spacer rides, to keep the axle from sliding side to side. That spacer is held in place to the axle housing by two large rivets, the heads of which are inside the axle tube. As the assembly wears, it deforms the rivets and/or elongates the holes in the axle tube allowing gear oil to seep onto the springs.

To fix that you would have to dismount the axle and remove the axle shafts. Using a piece of pipe as an anvil, placed into the axle housing from the side, we reset the rivets by hammering on the spacer. That tightened things up and I recall using a sealant around the spacers in addition. So far so good but I haven't put much mileage on the project yet.

It shouldn't hurt anything to leave it be, just put a pan underneath and keep an eye on the gear oil level. You can fix it later when need to do some other repair involving the rear axle.

Kent

Thank you Kent! I am actually hoping to put a 3.55 gear in the next few months in the rearend so I can address it then. Thanks again!

Has anyone ever welded the brackets and/or leaf spring pads to the rear end to eliminate a leak like this?

Big Tee,
You can't weld the brackets or spring pads to the axle housing because the axle needs to rotate slightly as the springs are compressed. Remember the torque tube is fixed to the differential carrier so as the rear end goes up and down as the springs flex something has to move to keep the drive shaft aligned with the differential. With an open driveline you have a u joint in front of the differential to allow the axle and springs to go up and down, at the same time keeping the drive shaft connected.

Note that the spring brackets on each side have a grease zerk to lubricate the area that is moving as your axle rotates.

Kent.

Thanks Kent. So it sounds like the only way to address this issue is as stated before, to pull the axles and address the perch rivets from inside each axle housing? It's now leaking on both the left and right side. This seems like it would be a common issue on these old rear ends but I'm not finding much out there about it or how to best address it.

Big T,
I don't know of another way to fix it. It will be a big job because to remove the axle housing you will have to disconnect the u joint behind the tranny, in addition to removing the rear u bolts and disconnect the rear brake line. You must also remove the axles from the housing. You will then have the rear axle housing, differential and torque tube as an assembly. The only other hard part will be finding the right sized pipe (around 3 inches as I recall) to just barely fit inside the axle housing to act as an anvil on the head of the rivets that hold the spacer. On mine we flattened the rivet heads sufficiently that the spacer no longer moved around in the wallowed out hole in the axle housing through which the oil was leaking. For added measure we applied sealant around the spacer although I am not sure that alone will help much.
My truck has been at the painter's shop for several months but as far as I know our repair has held up. If it leaks again, I will just get another drip pan or two and call it quits.

Kent

Thank you again Kent! When I get closer I may PM you for some further advice about using the pipe as an anvil. I'm assuming you put the pipe in the housing and beat it on the opposite side of the rivert to help flatten the rivet head for a seal.

Yes, you will be pounding on what I have called the spacer in my earlier posts. You will see the rivet heads start to deform if you look down the axle housing with a light. Also, the spacer will no longer wobble in the hole, which means you are expanding the rivet like it is supposed too. You will want to find a pipe that barely fits into the axle housing and you may want to wedge it tight with a wood shim. I wish I had taken pictures of this because there are a lot of trucks with this arrangement. Both my 37 and 42 are the same, but my 51 has different engineering to allow the axle to rotate the few degrees required. Good luck and feel free to PM me.
Kent