Rear Axle Seal Installation

Dennis/Arkansas

Dennis/Arkansas

Senior Member
Call me dumb but after wrenching for years I still can't figure out which way the seal faces when installing. The neoprene in the seals I have look the same from either side. By looking at the photos could someone please tell me which side faces the differential. I would really appreciate your help. Thanks, As Always, Dennis/Arkansas
 

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Don't feel bad, I've been looking through old manuals to try and find this very thing and haven't come across a manual yet that tells. I've heard of people putting two on each side with the lips opposing each other to prevent leakage. They may have been putting too much oil in the case though.

I've heard people say to put the open side out but all the seals I use in helicopter transmissions and aircraft turbine engines go with the open side in. Big ??? would like to know too.
 
lip, or spring toward the oil. if it's trying to keep the oil in,not dirt out. I think a boat seal may be lip out to keep water out.. They should have two way lip. Thats the way I have always done it.
 
Thanks Mick/mo. I have used seals where the spring was visible, unfortunately I can't see the spring on these seals. I may have to tear one apart to see which side the spring is on. Dennis/Arkansas
Mick/mo said:
lip, or spring toward the oil. if it's trying to keep the oil in,not dirt out. I think a boat seal may be lip out to keep water out.. They should have two way lip. Thats the way I have always done it.
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The garter spring should be on the open side. Normally that is the oil captive side but as Mick/mo was thinking out loud there is grease on the other side that can come in.
 
Dennis/Arkansas said:
Call me dumb but after wrenching for years I still can't figure out which way the seal faces when installing. The neoprene in the seals I have look the same from either side. By looking at the photos could someone please tell me which side faces the differential. I would really appreciate your help. Thanks, As Always, Dennis/Arkansas
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Referencing your picture on the left (#1?), that top end surface would go towards the drum/wheel end. The picture shown on the right (#2?), that side would go towards the banjo/differential gears. I made a little stepped tool from aluminum bar stock that attaches to a long rod. The seal slides over a slight interference fit on the aluminum piece and then that is positioned down inside the axle housing so the seal is starting into its mounting diameter. The seal is then driven in place by taping on the end of the rod.
 
Well JM 35 Sedan, that about seals it (no pun intended). I will install it that way. I have a goober to put them in that I got from Mac's. Thanks to you and all others who responded to my question. I will sleep well tonight! Dennis/Arkansas
JM 35 Sedan said:
Referencing your picture on the left (#1?), that top end surface would go towards the drum/wheel end. The picture shown on the right (#2?), that side would go towards the banjo/differential gears. I made a little stepped tool from aluminum bar stock that attaches to a long rod. The seal slides over a slight interference fit on the aluminum piece and then that is positioned down inside the axle housing so the seal is starting into its mounting diameter. The seal is then driven in place by taping on the end of the rod.
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[Thank you Master! Always great to hear from a Kung Fu fan! Dennis/ArkansasQUOTE=Ross in East Texas;29264]You chose wisely "Grasshopper"[/QUOTE]
 
The seal B-4245 is to keep the oil in the differential from getting on the brake shoes when a car is parked on a sideways slope. Look in the service bulletins (reprint), page 134 and you will see an exploded view of the rear axle assembly. The note on the seal says "install with sharp edge of leather toward differential".
 
jerry grayson said:
The seal B-4245 is to keep the oil in the differential from getting on the brake shoes when a car is parked on a sideways slope. Look in the service bulletins (reprint), page 134 and you will see an exploded view of the rear axle assembly. The note on the seal says "install with sharp edge of leather toward differential".
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Thank you Jerry, I appreciate it. Now if I can just get my addled mind to remember that next time I have to install a seal! Dennis/Arkansas
 
Think of the "sharp edge" as a pointer. Points to the oil. Don't pay attention to the outter body of the seal. I got a set of front seals for the 50 Custom I'm working on. The metal housing was stamped backward from what seals have been done like for eternity. I put one in the right way and one in backwards, and didn't think about it till I had the entire brake system together with wheels on and torqued :eek: Had to take one side back apart and fix.
 
Thanks 53ash, I really think I can remember that "sharp edge points to the oil". The problem with these seals is that the sharp edge only points down to the center, not forward or rearward. Thanks Again, Dennis/Arkansas
53ash said:
Think of the "sharp edge" as a pointer. Points to the oil. Don't pay attention to the outter body of the seal. I got a set of front seals for the 50 Custom I'm working on. The metal housing was stamped backward from what seals have been done like for eternity. I put one in the right way and one in backwards, and didn't think about it till I had the entire brake system together with wheels on and torqued :eek: Had to take one side back apart and fix.
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Another way to think about this is when the pressure is applied to the seal as shown in the left hand picture, the pressure will lift the lip away from the axle allowing fluid (or grease) to pass, kind of like a check valve. When pressure is applied to the seal as shown in the right hand picture, it will hold the lip tighter to the axle, sealing it tighter. If the seal is installed to tightly seal grease from entering the gear oil area, and it's heated and expands, the only other place it can go is past the outer bearing seal and into the brakes. You don't want that to happen! So, installing the seal with the side shown in the left hand picture towards the wheel hub bearings is correct. (I'm posting this because I installed my seals today without fully thinking this thru and Murphy prevailed!)

An additional concern is to install the DRIVESHAFT SEAL with the face shown in the left hand picture FACING the gear oil side (allowing pressure build up in the differential to vent out past the universal and through the transmission, rather than causing it to blow grease out into the brakes.)
 
Pack some wheel bearing grease into the sharp side of the lip, use a seal driver to install, sometimes they are a tight fit, I just did my 51 rear seals, one side went ok the other side was super tight. make sure axle retainer etc. doesn't rub on the seal outer metal surface, they must be seated all the way in.
 
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