1939 Rear Wheel Bearing Lubrication?

[Bob H]

The lube chart for my 1939 Special states that the rear wheel bearings are lubricated by differential lube oil. How does that happen? There is an oil seal inboard from the bearing that would keep differential oil from reaching the bearings, these are modern replacement oil seals look like they would block oil passage quite well. Were the original oil seals designed so or made of a material that would let some oil pass to lube the bearings?

 

One option would be to leave the inner seal out and allow free passage of the oil back and forth, but would the outer seal be able to prevent leaks into the brake drum? I noticed that the differential housing doesn't have a vent to relieve internal pressure like more modern housings have. I have pondered drilling a small hole in the inner seal to allow some lube oil to pass but that wouldn't allow it to return. Pack the rear bearings with wheel bearing grease?

 

I partially filled the bearing housing with a small amount of lube oil, maybe a tablespoonful or two. This probably will work short term but I am nervous about long term bearing life. Has anyone experienced bearing failure after replacing oil seals in their car? Thanks, Bob H

[LAS VEGAS DAVE]

I am not 100% certain but it seems to me that when I did my overdrive conversion I lubed the bearings with wheel bearing grease. I definitely didn't drill or modify in any way the housing. 

Edited October 2, 2016 by LAS VEGAS DAVE (see edit history)

[sleeve-valve]

I had the same question a few years ago. See the replies to this thread:

 

When I was in there I greased them just to be sure, installed new outer seals, and left the old inner seals thinking a little leaking from the inners can't hurt. It's been ok for 5 years so far.

[Guest]

Thanx for that info, you got a twofer on that one!

[Dynaflash8]

It was all the same from 1937-1955, and that's they way the factory built them.....and it worked.  I've wondered the same thing, but evidently the inner seal is not so tight that it keeps rear end oil from getting through, but instead just keeps it from flooding.  But, that's a guess.  All you really need to know is that engineers designed it, and its worked for over 75 years.  I guess the old saying applies.  Ours is not to reason why.......

[Bob H]

Thanks to all for the comments. Dynaflash8: I agree with your logic but still have a problem. If the inner seal I installed was 1939 vintage I would be inclined to go along with your recommendation. But, the seal is current technology and looks like it will keep differential lube from seeping into the bearing cavity. I believe that the original inner seals were leather and tended to weep a little at best. Add what I believe is positive pressure from the unvented differential housing and you have a source for lube oil to the bearing. I don't think the modern seal will allow oil to pass.

 

I was sort of fishing for someone who had installed modern seals and driven them more often with no bearing failures. Thanks again Bob H

[LAS VEGAS DAVE]

I have installed new modern seals and have driven at least 1500 miles since then, most on the freeway, with no problems. Keep in mind the I greased mine at the time of the new seals.

[Bob H]

Okay guys, grease it is! Appreciate the input, Bob H

[Guest buickguyflint]

I don't know why the manual you have says that they are self lubricating. But I can tell you for a fact that it is not

true. Rear wheel bearings on Buicks had to be hand packed with grease and this was done at the time you received

 a complete brake job approximately  60 to 75 thousand miles. Until 1956 when they removed the inner seal and

the 80 weight rear end grease was allowed to do the job without doing it by hand. Jim

[Jim Nelson]

I went over my rear end and re-laced the outboard bearings.  I have read about several guys who had problems and took the outboard bearing out.  Found them dry and lacking grease.  The design to libricate those bearings was put a seal to isolate the ring & pinion grease from the roller bearings.  The area around the outboard bearings was to have a seal on each side of the roller bearings and pack that area with wheel bearing grease.  The old seals were leather.  New ones are neoprene and I replaced both the race and roller assembly.  I have about 4-5 thousand miles on mine and I make long 6-700 mile journeys each way.  Buicks are made for driving ya know.