Axle seal technical question

So today we disassembled my driver side rear axle to replace a leaking axle seal. I was surprised how easy it was to break it down, get everything off and clean it up. We left the wheels on, removed the outer axle bolts, removed the axle shaft, then removed the outer hub bolts etc and removed the wheels and hub as one assembly with a makeshift tire dolley. I have a couple of questions to help me understand the mechanics of the seal design.

1) Is the space between the inner and outer seal supposed to be gear oil free? In other words, is the purpose of the seals to keep the bearing grease in and the gear oil out, in essence having a dry space where the bearings are for grease only? There was quite a bit of gear oil in the hub area where the shaft runs between the bearings and it had washed about all the bearing grease out of the bearings.

2) If the seals are supposed to keep the gear oil out, I can't figure out how it was getting in. The seals actually appear to be in good condition. If the gear oil travels down the axel shaft to the end where the end gasket and bolts are, in order to get in between the two seals it would have to get passed the outer seal first I would think and begin filling up in there, then at some point it would next have to get past the inner seal and start leaking out the inner side of the inner wheel where you begin to visually notice the leak correct? Why is there a space between the outer hub cap that bolts on and the outer seal which allows gear oil to pool, what is the purpose of this?

3) Is it possible for an outer seal to fail and make a visible leak on the inside of the inner wheel?

4) When the drum came off the brake shoes were clean and dry, the gear oil was leaking out of the inner seal and down behind the drum onto the tire rim, not entering the drum. Brakes are actually in very good condition.

5) When reinstalling the inner and outer seals, does it make sense to press the bearings and seals into the drum and then put the entire assembly onto the shaft to tighten it up to specs? Or better to get the inner seal on the shaft first, then the bearings and so on placing the drum on last? I know what the TM says, just wondering if anyone has done anything different and had any different results.

Just trying to make some sense of the engineering and failure process.

Thanks

1. Yes. The seals are supposed to keep the oil away from the bearings.

2. The key way was probably the culprit. It is generally a cork type material that slips in that key way, well it disintegrates.

Now I know there are a ton of threads here describing all the answers to these questions. I also think there is a step by step how to that I used. Try the search function..... that will pull up a bunch of threads on this plus some other members will chime in with the same advise. I'll see if I can't post some links to help you out

Here you go:

http://www.steelsoldiers.com/showthread.php?5935-leaking-axle-seal-repair.html

http://www.steelsoldiers.com/showthread.php?33428-rear-axle-seals.html

http://www.steelsoldiers.com/showthread.php?22288-rear-axel-seal-step-step.html

http://www.steelsoldiers.com/showthread.php?35043-rear-axle-leak-advice.html


Those should get you headed in the right direction

Thanks for the reply. I read through most of those threads including the one with all of the step by step pictures. They were excellent and very informative. I guess what's confusing to me is the modern axles which use the gear oil to lubricate the bearings and these which keep the bearing area dry with grease only. I now understand what they mean by adding extra grease for combat repacking, you could get a lot of grease in there. Not being an engineer, the logic behind the design will take me some time to comprehend.

It's cool. You also have to take into account that this is also older tech plus it was made for the Govt by the lowest bidder.

Thanks for the links ARYankee! There was one I hadn't seen before and it answered just about all of the questions. Thanks!