Ring, Pinion, Bearings and Axles-Pretty Ugly

[Janky59]

The following pictures are what was (unexpectedly) found when deciding to take care of an annoying leaking pinion seal. The differential in question is a #AF1229 (3.90, Happy New Year) from my '59 Apache.

It's like going under the knife for a hernia and the Doc telling you that you are all eaten up inside with cancer! A new seal, a new pumpkin cover gasket - oh my, look at this, it got worse in a hurry.

The previous owner had let it sit in a shed from about '08 to '15, but maybe this corrosion had taken place some years before - it's hard to say. As heavy as it is I sort of think so. Being in a shed, it was covered, etc. Maybe it was in a flood at some point in it's life. Since getting it running I've put about 3,500 miles on it, yeah, with it in this condition. Odo is showing 63,800.

Not being prepared for the extent of work and parts it would take to do it up right, we greased the bearing up, reassembled, refilled with 80-90 and buttoned it up. I've driven it 20 miles since and nothing's really changed. It still goes down the road, no new noises, not any quieter that I can tell.

Now, what's the thoughts on what direction to go? Run it like it is? (stock 235, no towing or any loads in the bed, flat terrain, highway speeds 30-40 miles at a crack). Or Don't drive it due to certain impending death

I'm inclined to keep driving it while I either a) source parts for a complete rebuild or b) swap out the whole diff for a similar year, (hopefully in better condition). Anybody want to sell a cast off 3.90 diff. cheap?

[dwcsr]

That's pretty typical of a rear that sets a long time. They collect water and then rust up every thing that's not in oil. 3.90 gears are getting hard to find so I'd run it till it drops and swap a late model rear into it. it may run years with the driving your doing. I've seen rears in that era with the carrier bearings completely gone run for several years

[1project2many]

One telltale would be to open the diff back up at the end of summer and check the oil and low lying areas for metal. If it looks like you could turn the oil into metal flake paint then it's certain death is not far away. If it's fairly clean then you probably have some time before it fails. If I expected to keep that diff I'd probably swap out the bearings. That's where most of the metal is likely to come from and it's the metal that will aggravate wear. The axle could be saved if needed. But folks here frequently remove perfectly good axles to swap with a later version so keep your eyes open. Don't forget that a "wanted to buy" post will be deleted if you're not a premium member.

[Katrina/10]

I like those old 3.90 axles. I have had a couple with rusty spots on the gears, but not anything like those. I found that most of the noise I had came from the axle shafts and wheel bearings looking like yours. Made quite a roaring sound till I replaced them.

[Janky59]

Dwcsr, you comments are appreciated, I was thinking along the same lines. I sort of like the idea of taking are of the axle bearings and monitoring things, thanks all.
I'll try to edit my post and take out the half hearted "want to buy" comment.

[OrrieG]

Run it until it starts making more noise. In the mean time get all the stuff you need to rebuild, bearings, axles, seals, etc. Gears look ok usually over heating is what will kill them. Keep in mind if you get another axle assembly you may be replacing some of the same parts if its been sitting. Make sure the vent is not plugged, it is supposed to allow condensation bleed off when air temps rise.

[_Ogre]

i'd run it too
as dwcsr mentioned, that's typical for any gear case; rear end or trans

Make sure the vent is not plugged,

it's a good idea to rotate the cover every time your down there to lube the shackles

[OrrieG]

Just had a flash back to the original Orrie, my grandfather, showing me how to check transmissions and rearends to make sure someone had not added sawdust to quiet them down. Also remember a lesson on how many cords of tire could be showing and the tires were still considered ok to use. During the Depression they did a lot of things to prolong a vehicles life....

[capnduane]

When I got my 55 2nd, among many other fixes, I drained the rearend. The stuff that came out looked like sheit. Literally! I just filled it up with fresh gear oil and it has been golden for the last 2 years. No leaks, howls, just works. I drive it most every day, altho my truck has a Pontiac 400, I baby it. The rearend is stock, I think, and at 60 yrs old, they must have been pretty beefy units?