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Backyard Mechanic
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OP
Backyard Mechanic
Joined: Nov 2007
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I'm dismantling the rear end from my 40 Chev 1/2 ton pickup for inspection. There was no gasket between the differential casting and the axle housing--it was sealed with blue silicone, so someone's been in there recently. The pinion engagement depth to the ring gear is controlled by shims placed in front of the front pinion bearing on the bearing seat in the housing. The shop manual indicates that the normal setup is two shims--a .015" and a .018" for a total of .033". The parts catalog calls for a gasket between the differential casting face and the axle housing. The thickness of this gasket will have a direct impact on the pinion depth. Can anyone tell me the correct thickness of the gasket. Thanks,
Mark Yeamans
VCCA #35724
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Technical Advisor ChatMaster - 10,000
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Technical Advisor ChatMaster - 10,000
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The thickness of the gasket mentioned, will not have any affect on the ring and pinion setting. There should be a very thin gasket in front and for the back cover.  
RAY Chevradioman http://www.vccacolumbiariverregion.org/1925 Superior K Roadster 1928 Convertible, Sport, Cabriolet 1933 Eagle, Coupe 1941 Master Deluxe 5-Passenger Coupe 1950 Styleline Deluxe 4-Door Sedan 1950 Styleline Deluxe Convertible 2002 Pontiac, Montana, Passenger Van 2014 Impala, 4-Door Sedan, White Diamond, LTZ 2017 Silverado, Double Cab, Z71, 4X4, White, Standard Bed, LTZ If you need a shoulder to cry on, pull off to the side of the road. Death is the number 1 killer in the world.
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Tech Advisor ChatMaster - 25,000
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Tech Advisor ChatMaster - 25,000
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The gasket used between the differential carrier and the axle housing is paper. The rear axle housing cover uses a cork gasket.  :) :grin:
The Mangy Old Mutt
"If It's Not Junk.....It's Not Treasure!"
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Shade Tree Mechanic
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Shade Tree Mechanic
Joined: Jun 2008
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I agree with AntiqueMechanic's response. When I took mine off a month ago, the gasket had compressed to something less than 1 mil - less than a sheet of paper, but thicker than tissue paper.
Lyn Gomes
1955 Chevy 1st series truck
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ChatMaster - 25,000
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ChatMaster - 25,000
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The thickness of the gasket will not change the ring gear to pinion settings as they are both supported and mounted in the differential housing. Infact if the shop manual method of setting the clearence is followd the adjustement is made with the housing out of the banjo housing.
Gene Schneider
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Backyard Mechanic
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OP
Backyard Mechanic
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Thanks for all the responses. On looking at the unit more closely, it's obvious that the differential housing to axle housing gasket does not affect the pinion depth adjustment, as the ring and pinion are a complete sub-assembly indepenent of the axle housing. Also, on cleaning up my unit, I discovered that there was, in fact, a paper gasket stuck to the axle housing. It measured .010" thick. A seller on Ebay has a NOS GM gasket for sale, and I asked him to measure the thickness. He replied that it measures .010".
Mark
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ChatMaster - 750
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ChatMaster - 750
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JYD, you mentioned a cork gasket behind the cover. I've just disassembled my original 1950, 3604 Eaton HO52 to replace the 4.57 with it nice 4.10. I was surprised to find a cork gasket behind the cover. I bought a haf dozen gaskets from AutoZone, and they are all the thin paper Felpro gaskets which are fine for the carrier side. But is anyone making the cork gaskets for the rear covers???
Denny Graham
Sandwich, IL
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Technical Advisor ChatMaster - 10,000
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Technical Advisor ChatMaster - 10,000
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Purchase a roll of cork gasket material and cut your own gasket.
RAY Chevradioman http://www.vccacolumbiariverregion.org/1925 Superior K Roadster 1928 Convertible, Sport, Cabriolet 1933 Eagle, Coupe 1941 Master Deluxe 5-Passenger Coupe 1950 Styleline Deluxe 4-Door Sedan 1950 Styleline Deluxe Convertible 2002 Pontiac, Montana, Passenger Van 2014 Impala, 4-Door Sedan, White Diamond, LTZ 2017 Silverado, Double Cab, Z71, 4X4, White, Standard Bed, LTZ If you need a shoulder to cry on, pull off to the side of the road. Death is the number 1 killer in the world.
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Joined: Nov 2001
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Tech Advisor ChatMaster - 25,000
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Tech Advisor ChatMaster - 25,000
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But is anyone making the cork gaskets for the rear covers??? Same answer as always......the Filling Station. Check out their catalog. By the way, here is a rule of thumb to go by: Between two machined surfaces a paper gasket will be used. Between a machined surface and a stamped steel surface a cork gasket will be used. :) :grin:
The Mangy Old Mutt
"If It's Not Junk.....It's Not Treasure!"
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I used a paper gasket for the cover side on my 37 with no problems. Jeff
VCCA #45194
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Well I would buy into that with sheet metal as on the engine, and since the rear cover is basically a sheet metal cover, I would go along with your theory and I can understand why they used the cork.
But the rear axle housing is a purty heavy forging. Unlike the later housing that were two stamped half’s welded together, the HO52 housing actually appears to be a forging. It is a full 9/16”+ thick at it’s flange and is a precision machined item.
I have been in contact with the people that maintained the vehicle for the village that bought it new. I got it right from them when they decided to auction it off. There is no record of any work ever being done on the differential. So I'm 99.9% sure that I'm the first one into this axle since it came from the factory and between the carrier and the housing is a thin paper gasket (.006”). A thick gasket in this location can push the axles shafts forward and load the side gears and outer wheel bearings. Also you would not want a thick gasket in the area because of the torque that occurs between the carrier and housing.
And I just checked with Scott at ”˜The Filling Station’ and the #G12087E differential gasket is paper, not cork as were the Fel-Pro ones that I got from AutoZone. I suppose I can cut a cork gasket from the 1/16" material that I have here for the rear. The only cork material that I can get is only 12" wide so it will be about an eighth shy on both sides, the cover is 12 1/4". When I was a kid, working in the auto parts store we had 3ft rolls of all types of gasket material on a rack that we could cut any size gasket from. Sure wish you could find that today instead of these prepackaged 12” rolls!
And I will again use the thin paper one for the front like the original one was.
Hey, JYD, thanks for stirring the pot, it made me dig a little deeper into it all.
Denny Graham
Sandwich, IL
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