Rear Diff Seal - Cant stop the leak

[Triv]

Hi gents. Looking for some insight. Not a mechanic, but not scared.

I have an '86 K10 with a 4" lift. Ive had the truck for (3) years, and when I bought it, I could tell someone had recently replaced the rear yoke. I noticed it leaking not too long after. I figured it was the seal, so I ripped it apart and replaced the seal. When I pulled it out, I did notice that the seal was different than what I had. I believe it was the seal for a K20 after doing a little digging. I popped the new one in and hoped for the best. It stopped the leak for awhile, but it's now leaking again. Could it be something else? Would the bearing behind the seal have anything to do with it? I was also thinking that since the seal was wrong when I replaced it, that the Yoke could potentially be wrong. Anyone have any info on this???

 

[Blue Ox]

Two possibilities, either there is a groove in the yoke where the seal rides which is damaging the new seal, or it just can't seal against it. Or you didn't get the pinion bearing preload right and it's moving around.

 

[Triv]

I inspected the yoke to make sure there was nothing that would cause a breach in seal. Any idea what the preload is? I just marked it with a magic marker and wrenched it down to where it was before I took it off. That could be the cause. I guess the correct way to do that would be to apply the parking break and wrench it down to the appropriate ft/lb tension???

Thanks for the info.

 

[Blue Ox]

To do it right you need a new crush collar and you have to pull the carrier out so you can measure the bearing friction. For an 8.5" rear you should be seeing 10-15 lb/in on used bearings.

Outside of that you're on your own. I know a lot of guys just torque them up and often get away with it, but it's not the right way to do it.

 

[73c20jim]

I used to crank pinion nut about a 1/16" or so past mark to insure preload. I think I read that in the factory repair manual for a 1971 Corvette.

I had a nick in the metal where the seal goes in. Cleaned it up and it worked great.