Dana 27 Leaking/fix

Since i replaced my spider gears, and inner axle seals, it seems ive developed a leak on the back side of my dana 27 diff, where the driveshaft conects. What seal is this? Im not going to fix every leak, i know, but id like to minimize leaks.

 

That would be the pinion seal. -Donny

 

Can i get to it from this side? I dont want to open up the diff, pull everyhing out, etc

 

Yes. Pull driveline, remove nut, pull off yoke and pop out the seal. Replace. Buy two because your rear axle needs one two.

 

Polish the yoke where the seal contacts and lube it also before you reinstall.

 

Funny you should say this, I picked up two yesterday, they both need it.

 

Put black RTV on the inside of the yoke at the rear and hold the washer tight when you install the yoke. This will help hold the RTV where you want it then install the nut and torque to 200-220 lbs ft.

 

Around the rim of the seal needs whatever sealer family you prefer. Permatex or silicone very lightly placed. Good time to clean up the yoke and sometimes need to polish the seal surface on the yoke to make the new seal last longer.

 

With these old axles you can pull the pinion seal and reseal em. The newer crush sleeve axles, you cant/shouldnt.

As was discussed. Drop the shaft, pull the yoke, gently work the seal out. I like to use a cascading series of big washers to slowly press in the new seal.

I use small bead of automotive silicone.

 

A Snap-on 2 3/16" 3/4 socket fits the seal perfectly for a driver.

 

Not true. GM even has specific instructions on how to replace a pinion seal on collapsible spacer differentials with only removing the nut, washer, yoke, and seal. This has been done for at least since the '60's successfully.

 

..and I've read the opposite in manuals. To each their own.

 

maybe I am overthinking this, but went to rock auto to order 2 pinion seals for my dana 27. for obvious reasons, I don't want the omix ada part. just too poor quality lately when ordering parts from them.
next step in line is the national brand, but then they have a bunch of options, so I'm thinking I have the 27-AF. but what is the 78.2 R.G. stand for?

 

If you have doubts about which part you need, start with the Jeep PN.

Oil Seal Pinion Model 25, 27, 30, 41, 44, 53

Walcks says it's 639265. Then go to RockAuto and cross that number in the PN look-up. This brings up SKF 15788.

More Information for SKF 15788

 

I just rebuilt my Dana 27AF and was recommended to use National 5778 pinion seal by Brian Hainer (guy knows his stuff, search metalshaper on youtube). On close inspection, this particular seal has a bead of some kind of sealant or silicone on the diff side where the gasket would normally be. Seemed like a good tacky seal and was there for a reason, so I left the gasket out. I cleaned up my yoke on a crank polishing machine, but leaving the gasket out might even move your seal in a few mm on your yoke for a new seal if yours is pitted or worn? Just a thought.

I haven't run it yet, but will surely update if my silicone seal/gasket delete theory comes up short.