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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Bruce W
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Re: Joe's MP rear main seal

Post by Bruce W » Sun Jul 25, 2021 2:09 pm

After measuring and writing the numbers, both on a sheet of paper and on the crankshaft, the same numbers four times, I stopped writing them. But all eight were within .0005, 2.310 to 2.3105.
BW
G Trp 2nd Sqdrn 3d Armored Cavalry Ft. Lewis 1970-71. 43GPW(Sarge?) 47CJ2A(Teddy) 47CJ2A(Rusty) 47CJ2A(Zak) 48CJ2A(Lefty) 48CJ2A(Uncle Linden) 53CJ3B(Bulldog) 88XJ(Pluto) NE CO


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Re: Joe's MP rear main seal

Post by 17thAirborne » Sun Jul 25, 2021 2:44 pm

Bruce W wrote:
Sun Jul 25, 2021 2:09 pm
After measuring and writing the numbers, both on a sheet of paper and on the crankshaft, the same numbers four times, I stopped writing them. But all eight were within .0005, 2.310 to 2.3105.
BW
Thanks, table updated
Oz

Feb 43 GPW 98532 USA 20206257
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Re: Joe's MP rear main seal

Post by Bruce W » Sun Jul 25, 2021 4:18 pm

Oz,
Your table should probably show my #’s 3 thru 10 as “CJ” or “PW” (Post War) rather than “GPW”.
BW
G Trp 2nd Sqdrn 3d Armored Cavalry Ft. Lewis 1970-71. 43GPW(Sarge?) 47CJ2A(Teddy) 47CJ2A(Rusty) 47CJ2A(Zak) 48CJ2A(Lefty) 48CJ2A(Uncle Linden) 53CJ3B(Bulldog) 88XJ(Pluto) NE CO

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Re: Joe's MP rear main seal

Post by 17thAirborne » Sun Jul 25, 2021 5:18 pm

Thank you sir. I just updated to PWCJ on 3-10.
Oz

Feb 43 GPW 98532 USA 20206257
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Re: Joe's MP rear main seal

Post by irakli » Mon Jul 26, 2021 9:58 pm

I measured RMS journal my 4 "scrap" crancshafts. I measured them in metric:

1. 58.70 mm. 2.3110"
2. 58.78 mm. 2.3142"
3. 58.63 mm 2.3083"
4. 58.68 mm 2.3103

3 of them are within specification. One is out, could be due to rust. I did not find any f marks on them.
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Re: Joe's MP rear main seal

Post by 17thAirborne » Tue Jul 27, 2021 4:46 am

Data Migrated from page 5
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
Irakli #1 UNK: 2.3110
Irakli #2 UNK: 2.3142
Irakli #3 UNK: 2.3083
Irakli #4 UNK: 2.3103

PWCJ: Post War CJ
UNK: Unknown

Percentage not ground: 18/18 = 100%
Average Diameter: 2.3105 Rounded to nearest 0.0005" or 1/2 a thou'
Raw Data: 41.5883/18 = 2.310461111
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" If anyone wants to check my math, I would be happy to see that. 4 eyes is better than 2.
Last edited by 17thAirborne on Tue Jul 27, 2021 4:49 am, edited 1 time in total.
Oz

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Re: Joe's MP rear main seal

Post by 17thAirborne » Tue Jul 27, 2021 4:47 am

irakli wrote:
Mon Jul 26, 2021 9:58 pm
I measured RMS journal my 4 "scrap" crancshafts. I measured them in metric:

1. 58.70 mm. 2.3110"
2. 58.78 mm. 2.3142"
3. 58.63 mm 2.3083"
4. 58.68 mm 2.3103

3 of them are within specification. One is out, could be due to rust. I did not find any f marks on them.
Thank you sir. Data updated
Oz

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Re: Joe's MP rear main seal

Post by 17thAirborne » Tue Jul 27, 2021 4:53 am

I took our data above and sent it to the technician, Roy at Best Gasket. He is very busy and is working on getting data to me on their seals. Hopefully he will see that the figures posted on the GPW drawing from Ford are in fact correct for GPW/MB and CJs up to the year 1950 at least. Jeep changed to the F4-134 in that year. I'm not sure if the RMS journal diameter changed at that point. I don't know if they continued to produce the crank for the L-134 for other CJ's after 1950. Not my area of expertise.
Oz

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Re: Joe's MP rear main seal

Post by YLG80 » Tue Jul 27, 2021 5:53 am

Hi Oz,
At the bottom of page 5 of this thread, Joe Friday has kindly posted two different RMS drawings. Thanks for these drawings.
I thought it was from an early and from a late crankshaft.
The first one shows 2.3085’’ to 2.3125’’ and the second 2.3125’’ +0.000’’/-0.004’’ which is the same mini diameter.

So my understanding is that they should dimension their gasket accordingly and we, the buyers/customers should take care of having our crankshaft RMS within the tolerances prior to reassemble our engine.
Yves
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Re: Joe's MP rear main seal

Post by dpcd67 » Tue Jul 27, 2021 6:48 am

Exactly, and that is what I have been saying; the RMS OD is not a secret, now, and it would be easy to make a seal that fit all of them. If the seal maker wanted to. It should not require spending $200 to have you crank welded up to a larger, non standard OD, just to make a bastard size seal, work. I think the seal maker did not actually measure a RMS journal, but a bearing journal. The guy who made the bad (too big) ones.
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Re: Joe's MP rear main seal

Post by dpcd67 » Tue Jul 27, 2021 6:51 am

Oz; of course they made L134 cranks way after 1950; the M38 was produced until 52 and spare engines were made long after that; they are the same spec. And so is the F134.
My fear is that on such a low demand item, Best Gasket won't want to do anything. No money in it. One seal mold costs more than they would ever make in the life cycle of selling seals. We think we are using lots of seals, but in this industry, it's nothing.
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Re: Joe's MP rear main seal

Post by Ron D » Tue Jul 27, 2021 9:48 am

We'd be using even less if they were made correctly.

I sure hope whoever makes and/or sells them can be convinced to mark their packaging with a unique part number, a date, and the spec tolerance it was made to seal. Buying unmarked seals is nothing but a guessing game gamble that can cost a lot of grief. Even if you measure your crank journal.

I'm not too concerned (yet) about the low demand. Best Gasket might be the only maker in town, but they have been making the RMS, and they also make the entire gasket set for the L134 (including a high quality copper head gasket). So I'm guessing it must be profitable. Rear main seal cost alone is approaching $30 each. If I knew it was correct and high quality, I'd pay that in a heartbeat. Maybe even two or three (lifetime buy).....because two is one and one is none.

And it wouldn't really surprise me to find out they're all being made you know where. Unless the package says "Proudly Made in the U.S.A." everybody wants to camouflage where it really comes from.
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Re: Joe's MP rear main seal

Post by 17thAirborne » Tue Jul 27, 2021 11:24 am

Gents, great comments all around. When Ron F. gets back from vacation and takes stock of this thread as he said he would, I can expect he will have a greater ability than all of us to influence what the manufacturer does.

Ron is only 1 of the 3-5 (or more) GPW/MB/CJ parts suppliers who have this same problem. It would behoove them/us to ensure they are somewhat in lockstep WRT getting these made correctly.
Oz

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Re: Joe's MP rear main seal

Post by dpcd67 » Tue Jul 27, 2021 11:59 am

True; I routinely pay $30 for the rubber seals (been lucky).
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Re: Joe's MP rear main seal

Post by Joe Friday » Tue Jul 27, 2021 1:05 pm

As far as I know, the L-134 crank with bolted/welded counter weights was used in Production Jeeps till at least 1971.
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