Inner rear axle seal

[FABRIC8TOR]

Ok/ thought I would chime in here
I have a 1970 M35A2 with a rear wheel seal leaking inside the drum . took wheels, axle and hub off seal looks good .
The only thing I see is the seal OD is roughly 3 3\8 across and the hub flange where I would think the outer seal should ceet into is 3 3/4. Tape measurements of course.
I may be missing something here but I would think that there is no way this would seal letting oil go from the the OD on the seal since there is 1/2 inch difference. Hope this is making sense.
I'm sure I'm missing something here
Anyway I may be able to get pics tomorrow as they are worth a thousand words...
The inner axle seal I removed has a part # of 19207 10896684 seems like the OD of this seal needs to be about 3 3/4
Thx in advance for helping out a newb to the green stuff.

 

[big block 88]

Post pics need to see it too know

 

[phil2968]

Your outer seal and the keyway cork is how the oil gets in. The rear seal just keeps dirt out and grease in the bearing. Start at the outside seal and keyway.

 

[clinto]

Phil is right. 99% of the time it's the keyway seal (the cork) failing.

 

[big block 88]

I always fill key way with silicone and then insert cork then seal have no leaks in 3 years on 4 trucks

 

[brianp454]

I think there may have been a mixup here.

If you look at the design of the rear axles carefully, the gear oil in the differential can (and does) spill over through the axle housing tubes all the way to the end of the spindles (the round part on the end where the bearing engage). This oil then is trapped between the inside of the drive axle flange and the outside of the inner seal. This oil lays there on a dynamic seal (engineer's way of saying it has to seal with moving parts vs. a static seal where nothing moves) and will eventually leak into the bearings where it will start to lay against the inner bearing; once the inner bearing starts to leak the gear oil and grease mixture ends up coating the inside of the drum, friction linings, etc. I'm finding that a combination of the outer seal and lack of RTV or wedge to seal up the keyway slot results in a royale mess of gear oil and grease on the brakes, making them severly degraded in their ability to function properly.

For the fronts, the different inner seal should keep the gear oil out of the u-joint and bearing area. With this design, the boot keeps grease in and crud out of the steering knuckle & u-joint area. The outer seal (same as the inner seal on the rear axles) keeps grease out of the front brakes. The hub on the end (or lockout) caps it all off. I'm finding that the front seals seem to hold up better, likely due to the lack of gear oil laying on a seal the way it does on the rear.

I think that if it's been 20 years since the truck was rebuilt and it hasn't had all of these seals replaced, they should be. Otherwise it's a liability that could and should be prevented. I also think that if it's been that long the master cylinder, air pack, and wheel cylinders should be rebuilt and the system bled with clean brake fuild. I've found some nasty crud and corrosion in places it shouldn't be. For all the talk of a single cylinder system, it is prudent to do proper maintenance and there's really no excuse not to.

My 2 cents.

 

[gringeltaube]

The only thing I see is the seal OD is roughly 3 3\8 across and the hub flange where I would think the outer seal should ceet into is 3 3/4. Tape measurements of course.
I may be missing something here but I would think that there is no way this would seal letting oil go from the the OD on the seal since there is 1/2 inch difference. Hope this is making sense.
I'm sure I'm missing something here
Anyway I may be able to get pics tomorrow as they are worth a thousand words...
The inner axle seal I removed has a part # of 19207 10896684 seems like the OD of this seal needs to be about 3 3/4
Thx in advance for helping out a newb to the green stuff.

The seal lip slips on the bearing face, not the hub. See this drawing....

G.

 

[OD_Coyote]

While you are at it, I would suggest verifying that the axle vents are working properly.

 

[FABRIC8TOR]

The seal lip slips on the bearing face, not the hub. See this drawing....

G.

Thx for the pic gringeltaube...Here is a link to an axle vent thread for those in the future who search.....http://www.steelsoldiers.com/showthread.php?113158-Axle-vents&highlight=axle+vents

 

[nmwildman013]

One other thing. I read on here one time that leaving the fluid level about 1/2 to 3/4 inch down from the level hole helps prevent oil from washing the outer bearing out. We tried that and now run all our trucks that way. Use the silicone, cork, plus fresh seals, good grease and don't fill it to the brim and you will be a happy camper. We have been doing this for two plus years with no problems on 5 trucks..

 

[gimpyrobb]

One other thing. I read on here one time that leaving the fluid level about 1/2 to 3/4 inch down from the level hole helps prevent oil from washing the outer bearing out. We tried that and now run all our trucks that way. Use the silicone, cork, plus fresh seals, good grease and don't fill it to the brim and you will be a happy camper. We have been doing this for two plus years with no problems on 5 trucks..

The only way for it to wash out the bearing is if it gets past the key-way seal. The level of fill has little to do with it, If that works for you, great, but I doubt it contributes much.

 

[Jeepsinker]

And why would it wash the bearing out? It doesn't wash out the internal bearings. Logic would dictate that as long as there is oil in there, even if it is displacing grease, it should run just fine. This is taking into account the leaks and brake problems associated with it. I've only seen bearings wash out/ wear out from lack of lube, not mixed lube.

 

[welldigger]

And why would it wash the bearing out? It doesn't wash out the internal bearings. Logic would dictate that as long as there is oil in there, even if it is displacing grease, it should run just fine. This is taking into account the leaks and brake problems associated with it. I've only seen bearings wash out/ wear out from lack of lube, not mixed lube.

The bearings run fine in oil bath. The problem is these seals won't keep oil from leaking out of the hub. Also both bearings can wash out. At least it did on 3 hubs on my truck.

 

[Jeepsinker]

Yeah I remember you telling me that, just trying to find out why some people keep saying that the oil washes bearings out. I've never seen a bearing in an oil bath go bad except from water contamination.

 

[DieselBob]

Yeah I remember you telling me that, just trying to find out why some people keep saying that the oil washes bearings out. I've never seen a bearing in an oil bath go bad except from water contamination.

Under normal circumstances that would be true. The problem/difference with these axle assemblies is that the inner seals where never designed to hold in a fluid like GO. They where intended to keep out contaminants just like grease seals on a boat trailer or the front hub bearings on a CUCV front axle. Because of the design of these housing assemblies the “full” level of GO in these axles is below the axle tube level so there is very little GO that will normally be available to the bearing hub assembly unlike a oil bath/wet bearing axle housing where the “full” level is above the bottom of the axle tube level to ensure GO goes to the hubs/bearings. When GO does enter the hub area and migrates past the outer seal, which is intended to keep the GO out of the bearing, it will tend to dilute and washout the grease in the bearing. This liquid lube soup now leaks past the inner seal which never was designed to contain oil so now you have very little grease or oil left to lube the bearings.

 

[Jeepsinker]

Roger that Dieselbob. Now I understand.

 

[Flyingvan911]

Just an observation. I just flipped the hubs and singled my deuce last weekend. Each differential has 6 quarts per the lube order. I repacked all rear bearing, new seals, etc at my friend's house. Drove about 10 miles back to the storage lot. Pulled an axle shaft and it did have some GO in the hub. Next day I drove about 30 miles and checked again. More GO in the hub. I believe over the course of normal on-road driving the GO is splashed around enough to run down the axle tubes and into the hub a little.

I plan to do a brake job in the spring so I can check to see if the GO gets past the outer seal. I knew I had GO leaking into the bearings. It turns out several of them had no grease at all left in them. They were being lubed purely by the GO. Only one bearing had to be replaced. All of the others were in good shape. I was suprised.

If I could redesign the axle/hubs a little I'd raise the full level of the differential so the GO level is about even with the axle shaft. The bearings would likely have plenty of lubrication from the GO.

 

[DieselBob]

Just an observation. I just flipped the hubs and singled my deuce last weekend. Each differential has 6 quarts per the lube order. I repacked all rear bearing, new seals, etc at my friend's house. Drove about 10 miles back to the storage lot. Pulled an axle shaft and it did have some GO in the hub. Next day I drove about 30 miles and checked again. More GO in the hub. I believe over the course of normal on-road driving the GO is splashed around enough to run down the axle tubes and into the hub a little.

Very true. Especially when the GO gets hot and expands. General splashing, going around corners and side slopes will cause the GO to get to the hubs, it just was never designed to use the GO for bearing lubrication hence the basic design. It sure would have been better if they would have used the same design as every other axle on the planet.

 

[acesneights1]

Can anyone tell me which TM covers this ?
I have a lsakkng seal but cant seem to figure oit which TM has the specs.

 

[welldigger]

Can anyone tell me which TM covers this ?
I have a lsakkng seal but cant seem to figure oit which TM has the specs.

Which seal do you think is leaking?