"Inside-out" seal

[Ed Landstrom]

Has any one found a source or modern replacement for the seal (GMC #2199398) in the rear spring mount on a DUKW. I don't know if the CCKW is identical, but I don't see why it wouldn't be.

For the amusement of anyone who hasn't had to cope with this seal, it's a 2 7/8 x 3 7/8 lip seal. What makes it unique is that instead of being pressed into the bore with the lip sealing on the shaft, it's pressed onto the shaft and has the lip on the outside, so it seals against the bore. People in bearing shops can't believe it exists, even when I show them my old one.

Apparently, the early trucks used a felt seal instead of a lip seal. I could make the felt part, but it requires a couple of retainers which I don't have. Besides, I assume the reason they changed was that the felt wasn't satisfactory.

Does anybody know why GM used such a strange seal? I've thought of modifying the part to take a conventional seal, but when I redesign something I always worry that there was a good reason that I've missed for doing it the original way.

[Richard Farrant]

Hi Ed,

I have come across this type of seal before, often in trailer hubs. Used in a hub it leaves the inner cone bearing on the shaft along with seal.
Check this link out, the seal is a common type and size used by other manufacturers as well;
http://www.autopartoo.com/oem/eaton/24550eaton.html This will allow you to widen your search.

regards, Richard

[rob love]

The M35 truck (MLVW in Cdn speak, as well as the old 5 ton gas and diesel military trucks) uses a seal like that for the inner seal. They are notorious for leaking. Worst thing is if someone installs the races using a punch....any nicks on the race ensure the seal can't seal.

[motto]

That seal is rather unique. Especially when you consider that it doesn't only have to keep lubricant in but also keep water out. It looks as though Richard has come up with a source for a replacement. I no longer have a DUKW SNL but the GM number given (2199398) looks good.
I have installed conventional seals in that position but have not immersed them so can't comment on their effectiveness for amphibious use. You could install them with the lip outwards to prevent water entry and pump grease through after service. Assembly using conventional seals is a little tricky as the seal must be on before the bearing cone and tapped into the spring mount as it is installed.
I have any amount of NOS pressed steel adaptor rings that are driven into the spring seat but no spare OEM seals.
When I purchased the surplus dealers stock many years ago included with it was 3,000 of the early type felt ring you mentioned that were obsolete during the war. I didn't know what to do with them and at the suggestion of a friend donated several hundred to a local kindergarten for the kids to play with. I still have a few about the place.

David

[Ed Landstrom]

Thanks. I've printed out the list of cross-matches and next time I go to town, I'll make the rounds of the bearing and truck-parts shops that couldn't find a replacement. Maybe one of them will be able to track down one of those numbers.

Apart from the difficulty of assembling the parts with a conventional seal, the other problem is that the shaft where the original seal is pressed on isn't finished to a standard that would allow the lip to seal against it. It could be mounted in a lathe and polished, but the shaft assembly is so far out of balance that the biggest part of the job would be fabricating and attaching a counterweight to allow it to be turned. Some people would do it free-hand with a belt sander, but I'm not that brave.

[Ed Landstrom]

I made the rounds of the bearing and truck parts suppliers today. None of them could find any of the 14 cross-match numbers. One old codger had a stack of the old paper catalogues that no-one else remembers, and spent half an hour going through them and calling contacts who usually have obsolete stock. No luck.

So what's wrong with these cross-matches? Did manufacturers use different numbers in the UK? ALL of them?
Are all of these numbers as obsolete as the GMC number?
One supplier suggested that this may be a proprietory part that was made only for GM, and never listed as available to anyone else.
I did notice that the list was published by a Chinese company, so maybe it's all lies. Though the dimensions they list are correct.

While looking at alternatives, it occurred to me that a simple way to solve the problem, rather than trying to polish the shaft, would be to machine a half-inch thick annular disc, a press fit on the shaft, with appropriate clearance in the bore, then cutting an o-ring groove in its outer edge. The o-ring would then serve as the seal. What am I missing? Why wouldn't this work?

[Richard Farrant]

Originally Posted by Ed Landstrom

So what's wrong with these cross-matches? Did manufacturers use different numbers in the UK? ALL of them?
Are all of these numbers as obsolete as the GMC number?
One supplier suggested that this may be a proprietory part that was made only for GM, and never listed as available to anyone else.
I did notice that the list was published by a Chinese company, so maybe it's all lies. Though the dimensions they list are correct.

Hi Ed,
Sorry you drew a blank here. I have used that website in the past to find alternative part numbers for bearings and seals without issue. Probably in this case it has been obsolete for some time.

Richard

[rob love]

I looked it up in my old Victor reference cataloques, and it seems that seal was used in some GMC rear wheels until about 1942. There were no listings after that. The seal was still listed in their 1965 catalogue, but not their 1970 catalog.

There are regular seals that would fit the shaft and bore you listed. Is there room in the housing to hold a seal?

[Ed Landstrom]

The existing seal is 1/2" wide, so a conventional seal of the same width would fit. One problem is that the part of the shaft where the existing seal is pressed on is not smooth enough for a seal, so it would have to be polished.

The other problem is that with the bearing pressed on the shaft and the seal pressed into the bore, there is no way to assemble them. Motto says it can be done by slipping the seal onto the shaft and gradually tapping it into the bore as the mount is slid onto the shaft. That looks like an awkward operation with lots of opportunity to foul up.

I had considered turning down the shaft to make the bearing a slip fit. This way both the bearing and seal could be installed in the bore and the mount could be slid onto the shaft just like a wheel hub. If there is any reason the bearing shouldn't float on both the shaft and bore, it could be held in the bore with Loctite.

Then I thought of making an adaptor to use an 0-ring. It seems so beautifully simple there must be something wrong with it. It wouldn't involve any modification to either the shaft or the mount and making the adaptor disc is a simple enough lathe job I could even attempt it myself.

[Tony Smith]

Originally Posted by Ed Landstrom

Then I thought of making an adaptor to use an 0-ring. It seems so beautifully simple there must be something wrong with it. It wouldn't involve any modification to either the shaft or the mount and making the adaptor disc is a simple enough lathe job I could even attempt it myself.

O-Rings don't like sealing on rotating surfaces such as hubs, but will tolerate sliding surfaces (as in a Piston Ring).

Perhaps a Speedi-Sleeve could be used to dress the surface to be suitable for a regular seal? Unfortunately, it might need to be removed and replaced each time the bearing is replaced, but how often do you expect that to be?

[rob love]

Is this on the spring mount for the trunnions (the spring mounts) as would be on a 6 wheel drive truck? If so I understand your dilemma of the assembly order. The later US military trucks are a similar setup but larger seals.

[Frank v R]

I have some of the felt ones in stock, send me a pm,

[Phil Waterman]

Hi All

This thread has bin ringing a bell, that the topic had come up before with some other thoughts here is the link,
http://www.mapleleafup.net/forums/sh...ght=tilt+angle

Having a problem copying the link but think it works.

If we are indeed talking about same seals I have been operating one of my trucks without the seal for years without any sign of gear lube getting through the bearings to the brakes. You really would have to have the truck on a steep cross slope for an extend period of time.

Cheers Phil

[Ed Landstrom]

Yes, this is on the spring mount. It is not a wheel hub. I thought an o-ring might work because there is no high-speed rotation. It only rocks back and forth a short distance, and at low speed compared to a wheel hub. An o-ring should at least be better than the felt washer that was originally used in this application. (But apparently the felt washer wasn't good enough because it was replaced by the lip seal.)

The speedy-sleeves I've seen won't work on such a narrow surface. It seems logical that there should be a style that will work, so I should look for a more comprehensive catalogue.

[rob love]

We have far more wear on those trunnion mounts than on a normal wheel bearing. The short travel back and forth seems to be very hard on the bearings and just as bad on the shafts themselves. Again though, that is on the MLVW...I can't speak to the vehicle you are working on.