Joe's MP rear main seal

1941 - 1945, MB, GPW Technical questions and discussions, regarding anything related to the WWII jeep.
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Ron D
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Re: Joe's MP rear main seal

Post by Ron D » Wed Jul 21, 2021 7:02 pm

For your viewing pleasure, from March 2020, here's Metalshaper's video on his 2.335 rear main seal crank journal dimension experience if using Best Gasket RMS. Starts at about 2:00 and runs to about 14:00, but the next part about the rubber dowel seals is also worth watching.

https://www.youtube.com/watch?v=CUOa4fgi1gg
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Re: Joe's MP rear main seal

Post by dpcd67 » Wed Jul 21, 2021 8:27 pm

HOLD THE PHONE!!!
I watched the video; (his handle is Metal Shaper; I had it wrong before).
He clearly stated, TWICE, that the historic RMS OD is 2.310; the same as we have measured and the same as called for in the AERA bulletin (2.312).
He did NOT at any time say that 2.335 was an original dimension.
So we can take that to the bank.
Now, the 2.335 dimension comes from his instructions to his crank shop, he tells them to weld them up to 2.335 so he can use the Best Gasket rubber seal. Which he determined, and showed in the video, to be too big for a standard, correct, 2.310 RMS journal.
This clarifies all the data in this thread; and puts it all in context.
Another BLUF; if you are using a Best Gasket brand seal, on a historically correct 2.310 RMS journal, it will leak.
Conversely, if you use a seal made correctly, on a 2.310 crank, it won't leak.
If you want to use a Best Gasket conventional, rubber, seal, tell your crank shop to weld up and grind the RMS journal to, 2.335. It then won't leak.
IF Best Gasket is the ONLY maker in the world of conventional seals, then they need to get with the program and make them fit the original, correct sealing surface of 2.312.
I do not know how many seal makers there are; I always heard that "early on" there were some "bad" seals out there, and now they have been purged from the supply system. Just what we have all read. No data.
Again, I have been lucky, by accident.
I think this sums it up.
Last edited by dpcd67 on Wed Jul 21, 2021 8:49 pm, edited 2 times in total.
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Re: Joe's MP rear main seal

Post by Ron D » Wed Jul 21, 2021 8:47 pm

Thanks for watching.......now you see what I was poorly trying to say (only that 2.335 is necessary for a Best Gasket RMS to seal). Pretty sure I never said he claimed it was the L134 spec dimension. Interweb comms are hard to do well.

Wait until Best Gasket puts out their new and improved seal........and there's both old and new Best Gasket seals all over the place.....confusion? Once again for the makers and vendors: put a darn date, a unique part number, and maybe even a spec or three on the package! How simple is that?

I suppose the good news is that if you have a machine shop build up your crank journal for an old Best Gasket RMS at 2.335, you'll have plenty of meat to turn it down 50,000 miles later for the new seal.
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Re: Joe's MP rear main seal

Post by 17thAirborne » Wed Jul 21, 2021 10:29 pm

I'll call Ron and ask him to read this thread. Better that he (the first customer who orders in bulk) gets with the distributor.
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Re: Joe's MP rear main seal

Post by YLG80 » Wed Jul 21, 2021 11:46 pm

A nice photo to add to that discussion: http://vehiculesmilitaires.com/download ... p?id=12208
Thomas has published yesterday that photo of his M201 crankshaft RMS area.
He has recently fully restored his jeep.
That is interesting as he mentions that the motorist has used a process named « schoopage » (Metal projection) after having surfaced the RMS area.
Schoopage : The projecting end electrodes are covered with a liquefied contact metal such as (tin, zinc or aluminum)... This metallizing process is named schoopage after Swiss engineer Max Schoop.
Unfortunately he did not take another photo after the schoopage process and we don’t know the RMS final dimension.
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Re: Joe's MP rear main seal

Post by YLG80 » Thu Jul 22, 2021 1:59 am

Ron D wrote:
Wed Jul 21, 2021 7:02 pm
For your viewing pleasure, from March 2020, here's Metalshaper's video on his 2.335 rear main seal crank journal dimension experience if using Best Gasket RMS. Starts at about 2:00 and runs to about 14:00, but the next part about the rubber dowel seals is also worth watching.

https://www.youtube.com/watch?v=CUOa4fgi1gg
Thanks for that video link. Really very interesting and well explained.

That's crystal clear: as underlined by dcpd67, Metal Shaper asked the shop to adapt the crankshaft rear seal journal to the Best Gasket seal dimension to provide with a proof.
It's kind of a return to the handy craft industry and it was necessary ...

So my conclusion is that Best Gasket designers have been using the standard main bearing journal dimension ( 2.3335''-2.3340'') to design their gasket.
THF405105_GPW-6303-A1_CRANKSHAFT_MAJOR_DIAMETERS-s1.jpg
Which by evidence is wrong and has catastrophic consequences on the engine!

Best thing would be to turn a measurement gauge to the correct dimension (2.310) and use it at the shop desk when buying a new seal :wink:
And if Best Gasket offers a new gasket with other dimensions, it's gone be a mess in the shop owners storage shelves.
As advised in the Lean philosophy, it would be good to clearly show the difference by changing the box color.

As Mike said regarding another problem, we should add that new key information to the TM, 3/4 of a century after it was written :D
Simply including the AERA TB 2025 document.

Yves

PS I'm delighted with dpcd67 expression : "So we can take that to the bank." :D
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Re: Joe's MP rear main seal

Post by YLG80 » Thu Jul 22, 2021 3:23 am

10 years ago from that thread: viewtopic.php?t=180498
I am confident that the information I have been given is accurate. I have spoken with a machine shop whom I have known for many years. They have built engines for me in the past as well. They have built hundreds of 134 engines.
They were also active with the AERA in this Rear Seal Information. AERA tech bulletin # TB2025 says that the seal surface diameter on the crankshaft must be 2.302 - 2.312 to use the lip seals now available.
This shop says he has measured dozens of different 134 cranks at this area and found as much as 15/1000" diameter larger than others. It makes sense that this is the case. This is why some of us have been OK with the lip seal and some have not. We know that some of us have even been unable to turn the crank with the new seals installed. So he always has the sealing surface machined to 2.30 in diameter and has not had any more problems with the seal/bearing failure. This is the seal surface located between the flywheel flange and the slinger collar.
So if you pull a crank for machining, have your machine shop resurface that narrow section to 2.30. Hopefully your shop will have the capability to do that narrow of a grind on their crank machine.
If you use a rope seal then they are forgiving enough for this variation of diameters from cranks over the years. But if you ever want to instal a lip seal,now or later, have it measured and machined if needed to 2.3.
I ,of course, welcome discussion further but as I said. This makes sense out of all the questions I have raised and the incosistent answers given by many.
Howard F Jewett
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I guess that Howard was writing about the oversized Best Gasket seals :lol:
Unfortunately the crankshaft drawing was not yet made available by THF.
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Re: Joe's MP rear main seal

Post by Wolfman » Thu Jul 22, 2021 5:35 am

Quick follow up on two things.
1 - You would not be able to just take one of the newer narrow rubber lip seals out of the box and measure the I.D. It is slightly spread open so when put into the seal groove in the block & cap it will squeeze in for a tight fit. It would have to be installed before you could get a good I.D. measurement.
2 - The old trashy lip seals that have hopefully gone away by now. These were really wide with a lip that hangs over the rear of the block. The rubber seal lip is 3/8 to 1/2 inch wide.
Do not use one of these. Period.
The GPW engine I have apart now had one. The engine was rebuilt, :roll: That is another story I won't get into now, several years ago and stored until now. Never run.
When I get out to the shop in a bit, I will reinstall the trashy seal and do some measuring.
Don't know if I have a narrow seal laying around or not. If I do I will do some measuring on it as well.
Stay tuned.
Mike Wolford
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Re: Joe's MP rear main seal

Post by dpcd67 » Thu Jul 22, 2021 7:54 am

All good and valid comments; now, the seal maker (assuming there is only one) needs to step up to the plate (Ok, another colloquial expression we often use, like taking it to the bank; I didn't invent these), and make the gaskets to fit the original crank OD. We should not have to alter the part to fit the seal.
Also, invoking LEAN principles is very insightful; yes, the seal maker should date all the seals and clearly make the box say, what it is for. Stop the confusion, which he caused in the first place.
The change was made by some last in his class engineer who, A: Did not run the ECP past a review board, and B: Didn't understand the Logistics impacts of his actions. Causing all this time, money, and frustration.
Yves; what you are explaining sounds like spray welding; which Metal guy says not to use. Not sure why.
Good point to get Ron involved in this. Who takes on this action item?
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Re: Joe's MP rear main seal

Post by Wolfman » Thu Jul 22, 2021 1:34 pm

I donated most of my day to this so,
The engine - GPW 95629. Block cast # GPW 6015 - Early 1943
Could not find a crankshaft forging #. Looked real hard. No Joy !
I did find a Script F on the crank by the front main bearing thrust surface. Also a "W". A "W in a circle" and a capitol "T". A # "12" was at a different location on the rear of the crank. ???
Crank has tapered dowel pins in the flywheel flange.
My bearing book listed Crank Forge # as possibly 630320. The earliest of several starting in 1942. ??
After this, other forging numbers listed were 635280. 635380, 638121, 641127 and 646318.
The crank mains are -.020 and measured 2.313". Std. being 2.333/2.334".
The rear main seal surface measured 2.311" and is smooth. This fits into the dimensions on Yves drawing.
As brought up before, this crank has been reground so, we don't know if anything has been done to the RMS surface. ??
If not, The smaller RMS O.D. still seems a little strange to me.
The rear main cap has a script F and the # GPW 6325 cast on it.
The oil seal groove depth in the block & cap are .270" deep. Thought I would toss that in.
No joy on the narrow rubber lip seal I thought I might have so no I.D. intel there.
The wide rubber lip seal that was installed in the engine when I disassembled it was marked 49650 and 800093. Had an arrow pointing the direction the crankshaft should rotate.
When installed in the block, the I.D. of this seal measured 2.295". That is plenty tight for a solid rubber seal. Again, the crank had been installed on this seal but never ran. This engine has set for several years. The seal lip surface is in good condition. Not burned up.
Gets better.
While searching for the narrow rubber lip RMS, I found another wide lip rubber seal. This seal had no markings at all but looked very similar to the 800093 seal.
I installed this "no name or number seal" in the block and measured the I.D. 2.220". :shock: That is tight !
May have something to do with past grief and the wide rubber lip seal self destructing very quickly.
Sums up my days activity.
Still be interesting to come up with intel on what the original RMS area shaft O.D. is and what the installed I.D. of the different narrow rubber lip seal available is.
Mike Wolford
CJ-2A
VEP GPW
Comm./Inst. SEL
AOPA ( 47 yrs)
EAA ( 47 yrs)
4th Inf. Div. - 5th Inf. Div. - 2nd Armor Div. - CIB

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Re: Joe's MP rear main seal

Post by dpcd67 » Thu Jul 22, 2021 2:49 pm

Good job.
However, I believe we have arrived at the correct OD of the RMS journal; 2.312, within a couple thou.
I do not understand why your RMS journal of 2.311 seems strange/ too small, when it is exactly what the AERA bulletin says, and the drawing says, and the M38 I measured which I know has not been ground. And what Metal guy said they were.
I now believe that it is/was the seals being the wrong diameter, all along. Just as Metal Shaper says.
He compensated for bad seals by having his cranks welded up; a situation I hope the seal maker will resolve.
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Re: Joe's MP rear main seal

Post by YLG80 » Fri Jul 23, 2021 12:20 am

Wolfman wrote:
Thu Jul 22, 2021 1:34 pm
I donated most of my day to this so,
Hi Mike thanks for spending your time on this. Tractors and mowers will have to wait :D .

The rear main seal surface measured 2.311" and is smooth. This fits into the dimensions on Yves drawing.
As brought up before, this crank has been reground so, we don't know if anything has been done to the RMS surface. ??
If not, The smaller RMS O.D. still seems a little strange to me.
The RMS O.D. does not look odd to me, as it is on the high side of the tolerance and could be the original dia.
Regarding the thight seal, you could find more information here: viewtopic.php?t=180498#p1045258

Most probably it’s a Victor seal as confirmed by this comment:
(Note: the 49650 is the Victor Part Number and the 800093 is the Willys Part Number.
Victor put both on the seal because they were the OEM supplier of the seal to Willys) ( From the 90's on Victor supplied this seal to Felpro for their kits as well.)
source: http://www.willysmjeeps.com/v2/modules. ... 4094#24094

That seal has really a very long history…
Yves
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Re: Joe's MP rear main seal

Post by YLG80 » Fri Jul 23, 2021 1:38 am

Hi Mike,
This preformed reals seal 800093 sketch could be of some help in your measurements.
L134_Crankshaft_800093 Rear Main Seal_Late type_sketch-3s.jpg
It was sketched most likely by the company Victor between 1951 and 1953 (see notes)


Early and late engine block crankshaft grooves for seal

CRANKSHAFT_SEAL_GROOVES_EARLY-LATE.jpg

Yves
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Re: Joe's MP rear main seal

Post by Wolfman » Fri Jul 23, 2021 5:17 am

Thanks for the links, Yves.
They were both good intel and I especially liked the second on Wes K's post form 2005.
Put dates on when different type seals were used and when the later wide rubber seal was introduced, ( another question on my mind ), as well as when the issues with these seals began.
The seal I removed from the engine with the OEM numbers may be OK. It fit into the specs on the diagram you posted, as does the crank.
The second no number seal I found was a piece of crap. Way out of spec. The seal lip did not even look or feel right compared to the OEM seal.
Going to hang it on the wall as an example of what not to use. 8)
When this engine goes back together, it will have a rope seal.

Mike
Mike Wolford
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EAA ( 47 yrs)
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Re: Joe's MP rear main seal

Post by dpcd67 » Fri Jul 23, 2021 7:43 am

Yves; that first drawing of the seal and crank dimensions says it all; this should be the standard for making all seals. Now this information has to get to the seal makers, whomever they are. And to all potential engine rebuilders here; so they can measure that RMS journal; which I never did before. But Abrahams did; I just didn't know it.
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