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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YLG80
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Re: Joe's MP rear main seal

Post by YLG80 » Fri Jul 23, 2021 9:39 am

Perhaps time to give an advice to Gary, the OP.
Already 1100+ hits on that topic dated from July 17th. :mrgreen:
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Re: Joe's MP rear main seal

Post by 17thAirborne » Fri Jul 23, 2021 12:21 pm

I just spoke with Ron. He is aware of the current RMS problems and has been in discussions with Best Gaskets. This is why he now only offers a rope seal until further notice. He Will read this thread, but is going on vacation tonight. He will respond when he returns and has an update.
Oz

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Re: Joe's MP rear main seal

Post by dpcd67 » Fri Jul 23, 2021 1:55 pm

Very good; thanks for doing that.
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Re: Joe's MP rear main seal

Post by YLG80 » Fri Jul 23, 2021 10:50 pm

The different seals:

The seal measured by Mike, with Victor & Willys part #.
91480700-0B39-4EDF-8E50-2F51E4879881.jpeg
A08CFCDF-7208-429B-9E56-92DB762285B2.jpeg

The correct and workind Best Seals.

DBB174DC-5FF2-46B9-93A5-DD69452E3B61.jpeg

The rope seals, Ford GPW box.

963434D0-DE2B-4697-8DE0-3270388C136E.jpeg

Detail of the original rear seals
CB91923D-2E57-48AA-8413-6335C6A78E75.jpeg

Another important note: do not soak the rope seals in oil prior to the assembly.
The oil dissolves the graphite from the inside of the rope.
Prefer Metal Shaper method who is using vaseline.
It’s perfectly shown in his video: https://youtu.be/e39dNzVYsP8

Yves
Last edited by YLG80 on Sat Jul 24, 2021 8:05 am, edited 2 times in total.
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Re: Joe's MP rear main seal

Post by Mike Kelly » Sat Jul 24, 2021 1:30 am

My take on it is: rope seals are more forgiving , they don't require a perfect journal surface or a precise journal dimension in order to seal effectively.

A engine rebuilder described to me how he does a rope seal, he uses permatex sealant under the seal where it fits in the groove and he applies grease on top where the seal runs on the journal, this grease application is done so the seal will not burn during the first start up process.

I followed his directions and have done a few engines with no problems at all . This is just my experience , I'm not a professional just a hobby person. The journal can be polished with emery cloth if the journal is not damaged severely.

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Re: Joe's MP rear main seal

Post by Wolfman » Sat Jul 24, 2021 4:44 am

You struck a nerve, Yves.
Don't soak the rope seal in oil.
These seals running dry on start up is a problem. I see the point of not soaking the older graphite impregnated rope seals but the new, white material type rope seals are not graphite impregnated and need all the help they can get.
These seals run in oil and oil lubrication makes a difference between their life & death. Especially on first start.
John Gibbins ( Articifer ) posted a link to a shop in OZ showing the proper way to install a rope seal back some time ago. This was on an aluminum block Buick engine but same process. One of the things the guy did in the video was soak the rope seal in oil all night before installing.
As for a coating of grease ??? First off, what kind of grease ??
My experience with grease is, it is thicker than oil. :roll: Obviously. To become fluid and flow, it has to warm up. We are talking first start and rapid heat build up. Don't have time for the lubricant to warm up and flow. Use oil.
The oil in the soaked rope seal also acts as a heat transfer medium. Takes the heat away from the seal surface and helps keep it cool at the critical Moment. First Start.
Thanks for posting the picture of the seal I was referring to earlier. One of these days, guess I need to get a digital camera and learn how to post pictures. In the mean time, you are doing a great job. I appreciate it !
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Re: Joe's MP rear main seal

Post by dpcd67 » Sat Jul 24, 2021 5:51 am

Not a digital camera; it ain't the year 2000. Cell phones all have cameras in them. If you have an iPhone, and a MAC, it automatically puts the pictures on the computer the instant you take them.
Anyway, I, too, have installed many rope seals in L134s, and one 340 4 barrel.
None leaked.
I soaked them in oil for several hours. I put permatex on the ends and on the dowels. I used assembly lube on the journal. As stated, after all, they live in oil their entire lives.
However, even though rope seals are not hard to install if you seat them firmly and cut the ends off right, the rubber seals are easier and I would like everyone involved to get them right. Meaning the makers, and sellers. A rope seal would not be more forgiving if the rubber seals were made to, and the owners knew, the dimensions they were dealing with. But running blindly, yes, rope seals will mask a lack of knowledge of dimensions.
Once everyone (Users, Makers, and Sellers) has documented journal dimensions, there is no excuse for any more leaking Rear Main Seals. None.
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Re: Joe's MP rear main seal

Post by Joe Friday » Sat Jul 24, 2021 5:58 am

Wow.

This almost feels like the 'old' G has returned.

I'm glad to see such a comprehensive analysis here.

I am a bit confused why my searches didn't pull up many of the old posts on this subject.

I posted the Engineering Print of the Rear Main Seal crank surface dimension and the seal drawings about 10 years ago on this site to demonstrate that the AERA bulletin was CYA, and showed the manufacturing non-conformances with the Victor seal. (I still have about a dozen of the them).

Great job!

I look forward to the updated product. This might be one case where procrastination worked in my favor since I've got 3 cranks waiting to be installed
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Re: Joe's MP rear main seal

Post by 17thAirborne » Sat Jul 24, 2021 6:25 am

REQUEST: Please post your RMS Journal Diameter on this Thread so we can begin to understand what percentage of them have remained unground. I'll update the data.

OZ GPW: Diameter 2.3105
DPCD67 M38: 2.312
Wolfman GPW: 2.311
Yves GPW: 2.311
BW #1 VECJ: 2.3095
BW #2 GPW: 2.3085
BW #3 PWCJ: 2.3105
BW #4 PWCJ: 2.3100
BW #5 PWCJ: 2.3105
BW #6 PWCJ: 2.3100
BW #7 PWCJ: 2.3105
BW #8 PWCJ: 2.3100
BW #9 PWCJ: 2.3105
BW #10 PWCJ: 2.3100

Percentage not ground: 14/14 = 100%
Average Diameter: 2.3105 Rounded to nearest 0.0005" or 1/2 a thou'
Not totally scientific as I used 4 of BW's shafts at 2.3100 and 4 at 2.3105, but the data will still confirm what we know to be the correct RMS surface diameter. Once might suspect that those below 2.3100" have been "polished"
Last edited by 17thAirborne on Sun Jul 25, 2021 5:17 pm, edited 4 times in total.
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Re: Joe's MP rear main seal

Post by 17thAirborne » Sat Jul 24, 2021 6:34 am

Had to laught when doing my daily search for generic GPW parts this came up. Someone is reading our posts :lol:
RMS Ebay.png
Oz

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Re: Joe's MP rear main seal

Post by YLG80 » Sat Jul 24, 2021 8:27 am

17thAirborne wrote:
Sat Jul 24, 2021 6:25 am
REQUEST: Please post your RMS Journal Diameter on this Thread so we can begin to understand what percentage of them have remained unground. I'll update the data.

OZ GPW: Diameter 2.3105
DPCD67 M38: 2.312
Wolfman GPW: 2.311

Percentage not ground: 3/3 = 100%
Average Diameter: 2.3110 Rounded to nearest 0.0005" or 1/2 a thou'
Yves GPW crankshaft RMS
From my notes : original not grounded 2.3110
From my photos : slightly pitted, polished.

Yves
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Re: Joe's MP rear main seal

Post by 17thAirborne » Sat Jul 24, 2021 9:12 am

Yves: thank you sir. Data posted and changed.
Oz

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Re: Joe's MP rear main seal

Post by dpcd67 » Sat Jul 24, 2021 9:36 am

Nice staff work. As if you guys served in the Division G4.
As for ground RMS journals; I know for a fact that Abrahams will NOT grind that surface unless they first weld it up and then grind it back to standard dimensions; for all cranks. They have told me that in the past; but I was not savvy enough to ask what the actual spec was for a 134 engine. I just had my M606 done last fall, but it is already assembled and running; of course I didn't measure it! They welded it and ground it back. That would have been a good data point.
I know; there are no good or bad data; just data.
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Re: Joe's MP rear main seal

Post by 17thAirborne » Sat Jul 24, 2021 9:43 am

dpcd67 wrote:
Sat Jul 24, 2021 9:36 am
Nice staff work. As if you guys served in the Division G4.
As for ground RMS journals; I know for a fact that Abrahams will NOT grind that surface unless they first weld it up and then grind it back to standard dimensions; for all cranks. They have told me that in the past; but I was not savvy enough to ask what the actual spec was for a 134 engine. I just had my M606 done last fall, but it is already assembled and running; of course I didn't measure it! They welded it and ground it back. That would have been a good data point.
I know; there are no good or bad data; just data.
Great points all around.

Hopefully if we can get around 30-50 data points that indicate MOST RMS journals are near the 2.310" size, it will have a bearing(really...no pun intended) on what Best/RFJP and the others will do regarding meanufacture and sale of RMS's.
Oz

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Re: Joe's MP rear main seal

Post by Joe Friday » Sat Jul 24, 2021 10:29 am

I'm pretty gullible, but I always thought both the early and late crankshaft all had the same RMS journal diameter.
It appears here the diameter tolerance on the crank is wider. Same upper limit though.

Image

Image
Last edited by Joe Friday on Sat Jul 24, 2021 10:44 am, edited 1 time in total.
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