Rear Crankshaft Seal Retainer

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Rear Crankshaft Seal Retainer

Postby Jim Becker » Wed Jul 20, 2011 4:37 pm

Here is some recently found informaton on the R1 vs. R2 rear crankshaft seal retainer.

Service Bulletin S-7625, June 10, 1954.

Rear oil seal 251 378 R92 replaced with 360 662 R91, difference is that the new seal outside diameter has a thin layer of synthetic rubber.

Retainer 251 363 R1 revised to R2. Principal changes:
- locating shoulder for seal revised to locate seal 1/16 farther from front chamfer on crankshaft seal surface.
- fillets increased on seal entry side.
- retainer boss diameter increased from 4-1/4 to 4-5/16.
- added radius at 3 mounting holes.

The seal retainer assembly part number advanced from 251 363 R11 to 251 363 R21.

Note that this list includes no indication of a change in the diameter of the seal bore.
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Re: Rear Crankshaft Seal Retainer

Postby Hengy » Thu Jul 21, 2011 6:48 am

Excellent research, Jim!! Are they referring to the seal bore when they say the following:

- retainer boss diameter increased from 4-1/4 to 4-5/16.
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Re: Rear Crankshaft Seal Retainer

Postby Jim Becker » Thu Jul 21, 2011 8:28 am

I believe that is refering to outside diameter of the part of the casting that the bore goes through. The bore diameter is well under the quoted 4-1/4 or 4-5/16. I think the effect was to add thickness to the part of the casting that holds the seal.
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Re: Rear Crankshaft Seal Retainer

Postby Hengy » Thu Jul 21, 2011 8:36 am

I see what you mean. Do you think that the seal diameter was an "on the fly" thing when the seal manufacturer discontinued the original seal size? I think it is interesting that they never refer to the seal at all in the discussion...

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Re: Rear Crankshaft Seal Retainer

Postby Jim Becker » Thu Jul 21, 2011 9:11 am

They state that the change to the seal was addition of the rubber coating on the outside. At this point, I don't believe there was ever a change in the bore diameter. Back in January, Rick measured the bores in each of a small stack of retainers. The measurements were all over the place with R1 and R2 measurements overlapping each other. The R2's seemed to a bit more than the R1s. That adds credence to someone's conjecture that a tighter fitting seal could cause more warpage of the retainer. I presume the rubber coating causes a somewhat tighter fit in the same bore.

Looks to me like they enlarged the boss to reduce warpage and added the coating to the seal to keep it from moving when the retainer was hot.
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Re: Rear Crankshaft Seal Retainer

Postby Rick Prentice » Thu Jul 21, 2011 9:35 am

I know guys will be asking about the tests I did, so here's a copy from my word document with all the results:
All the parts started at 49.5 degrees, according to my new Snap-On unit. I have the oven set at 200 and shows that on the Snap-On at the beginning of the bake-off. I'll check things at 8pm my time. I have 6 new CR29952 seals, 2 National 355526 rubber coated seals, and a TTO G958 rubber coated seal. I also have two R1 retainers, two R2 retainers, and one machined retainer with the new CR29952 and the new snap-ring feature. This reworked retainer also has a top quality expensive rubber sealant used.

I baked the parts with oven set at 200(actual 212) for 1/2 hour, then baked set at 250(actual 260) for another 1/2 hour.

CR29952 seals-at @50degrees----------------212degrees--------------------------260degrees
1) 4.010-----------------------------------------4.012---------------------------------4.015
2) 4.010
3) 4.009
4) 4.009-----------------------------------------4.013---------------------------------4.015
5) 4.0095
6) 4.010

National seals(new)
1) 3.878------------------------------------------3.885--------------------------------3.891
2) 3.881------------------------------------------3.884--------------------------------3.885

TTO G958 seal(new, came in a gasket kit)
1) 3.880------------------------------------------3.894--------------------------------3.895

retainers:
R1
1) 3.852-bot,3.852-top -----------------------3.855bot,3.860top-----------------3.856bot,3.861top
2) 3.857-bot,3.861-top -----------------------3.862bot,3.867top-----------------3.868bot,3.873top

R2
1) 3.855-bot,3.859-top------------------------3.860bot,3.866top--------------3.868bot,3.870top
2) 3.875-bot,3.8881top------------------------3.884bot,3.889top--------------3.889bot,aborted measurement
I found out this last R2 retainer (no2) retainer is out of round bad. I was checking from top to bottom. The side to side measurement is down in the 3.852bot,3.855top range. I then checked all the other retainers and they have perfectly round bores.

The reworked R1 retainer was bored to 4.003 and a CR29952 pressed in. At 212 degrees it seems tight and ok, at 260degrees it's still tight. It's too difficult to get a measurement without taking it apart.

Stay tuned. I also plan to scrap off the rubber coating on the IH seals, just to see how thick the coating is. When both retainers and seals are cold, they pressed into the retainer with minimal finger pressure. There's no way I'd install them without some sort of sealer added.

I took the National seal marked (1) and removed the rubber jacket off the outside. It now measures 3.825, meaning the rubber coating totalled .053 thick(.0265 on a side) The rubber when new feels soft and pliable.


Rick
Last edited by Rick Prentice on Thu Jul 21, 2011 9:47 am, edited 1 time in total.
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Re: Rear Crankshaft Seal Retainer

Postby tst » Thu Jul 21, 2011 9:40 am

Hi Jim, that is great info, but the bottom line is we cannot buy a seal to fit correctly in the retainers and that is why we need to bore them and use some other style seal?, has any one found a rubber clad seal that will fit the retainers with out maching them?
I have taken apart many with the rubber clad seal and most were dry with no problems, we just need a place to buy new ones
thanks Tim
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Re: Rear Crankshaft Seal Retainer

Postby Jim Becker » Thu Jul 21, 2011 10:06 am

Tim,
The problem with finding a replacement seal is that nearly all existing retainers have warped and no longer properly hold the original seal. The answer to your question as to what seal will fit without machining is quite simple, use the CaseIH supplied seal in an retainer that hasn't warped. Rick has put a LOT of effort into an alternative for the nearly 100% of us that doesn't work for.

Part of the difficulty of Rick's work is the fact that the retainers he has to work with are all used parts whose dimensions have changed in varying amounts. He has been confronted with the question as to how much of the difference is due to warpage and how much is due to differences that were manufactured into the parts.

The whole point of my posting the information from the service bulletin was to provide insight to the manufacturing differences part of the question. I glean 2 major points from it.
1) Original bore diameter was evidently the same on all retainers.
2) When reboring for a larger OD seal, an R2 retainer is probably preferred bacuase there is more material surrounding the bore.

As a bonus, we now have an approximate date for the change to the R2 retainer. Any tractor built after that can be generally expected to already have an R2 retainer, giving a better idea what will be found when the tractor is split.
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Re: Rear Crankshaft Seal Retainer

Postby tst » Thu Jul 21, 2011 10:20 am

I know a lot has been said on this subject, thanks to Rick, Jim and others that have tried to find the best way to keep the oil on the insides of our engines instead of running out the torque tube, I guess i have been lucky, i machine them and use the national seal # 355526 with the plastic coating on it, I have never had one fail, I make them a tight fit using the theory that it will stay in the retainer when its hot and expands
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Re: Rear Crankshaft Seal Retainer

Postby Landreo » Mon Jul 25, 2011 4:27 pm

tst wrote:Hi Jim, that is great info, but the bottom line is we cannot buy a seal to fit correctly in the retainers and that is why we need to bore them and use some other style seal?, has any one found a rubber clad seal that will fit the retainers with out maching them?
I have taken apart many with the rubber clad seal and most were dry with no problems, we just need a place to buy new ones
thanks Tim


If the seal retainer is within the out of round tolerance then a rubber seal will work. I did a functional test, put 3 rubber seals and 3 metal seals in the same seal retainers, all fit tight, heated to 212 degrees and all of the steel cased seals were loose, none of the rubber seals were loose. Rick's numbers also seem to that result.

If your retainer is good, it can be checked with a $15 caliper, then use a rubber seal. If the retainer is out of tolerance then get another retainer or bore the absolute minimum to get it back to round. I would expect less than 0.01 inch would be enough. Too much and you may weaken the bore. Put in a rubber seal to fit the new bore size. Don't use a steel cased seal.

There is a reason why IHC stopped using the steel seals and went to rubber seal, there is a reason all the seal manufactures and all the seal books I have read recommend a rubber seal for this type of application. Rubber seals have a greater tolerance for seal bore expansion from heat and a greater tolerance for out of round seal retainer bores.

5 minutes on the internet and you can find the seals you need. I have a bunch of Harwall seals the same as the National seals except 3/8 vs 1/2 inch.
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Re: Rear Crankshaft Seal Retainer

Postby Jim Reid » Mon Jul 25, 2011 6:20 pm

I just finished replacing the rear seal in my 71 with the national 355526 and it had to be forced in i haven't cranked it and used it any but i don't think it wil leak.

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Re: Rear Crankshaft Seal dimensions

Postby jafa » Sun Aug 14, 2011 1:35 pm

What is the inner diameter and thicness of the seal??
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Re: Rear Crankshaft Seal Retainer

Postby Groove Critter » Mon Aug 15, 2011 7:19 pm

I read the previous info in this post and I see:

"The seal retainer assembly part number advanced from 251 363 R11 to 251 363 R21.
Note that this list includes no indication of a change in the diameter of the seal bore."

I have a question. The quote above specifically mentions the "assembly part number". If we could get an actual print of the part we would not have to rely on the assembly number vs. the part number. Or, was the part number what was meant in the prior quote?

Regardless, is there a drawing of the aluminum seal retainer available?
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