Replacing differential front seal

When I was changing out the air shocks I noticed that the front seal on my differential. Is there anything special about replacing it? I assume I need to drop the drive shaft, hook the seal, and drive in a new one. The cover gasket is still dry. I'm tempted to change the seal and top it off, unless it's recommended to switch to synthetic. It's an open carrier.

you will need a new crush collar it will not effect the pinion depth that is determined by the pinion shim that is located under the pinion bearing. you will need a inch pound torque wrench. after the initial buckling of the crush coller you will use the torque wrench to see if you have enough preload on the bearing by turning the pinion nut. if you go past the correct point, meaning it takes to much pressure to turn. then the crush collar is ruined. you could also get a solid pinion spacer and get rid of the crush collar

That settles it. I'll top up the fluid! It didn't appear to be a major leak. I naively forgot the yoke flange. I've rebuild differentials for my Corvairs, but they've got threaded bearing sleeves for both the pinion and carrier. So they're very easy to make adjustments in any direction. I have a beam style inch pound wrench but it's a small 1/4 drive one. If I go to the trouble to learn to work on these, I'll wait until I can afford 3.42 gears and a new posi carrier.

Thanks for straightening me out guys.

mtrhead79 wrote:

you will need a new crush collar

Not really,. just snug the nut up till there's a little drag,. long as the bearing has a little pre load its fine,..

rear ends get pretty sloppy,. lots of times you can remove the driveshaft and snug the nut up some, and the seal quits leaking,.

but do as you want , you're gonna anyway,.

YRMV,............. cos i know what i,m doing,..

hey i am not the best to take advise from i started with doing the rear and wound up taking the whole car apart

Hmm, learn to live with the leak, or face the prospect of rebuilding the entire unit.

Not much of a choice.

Or you could open up the FSM and follow the seal replacement procedure outlining how to match-mark the pinion, nut & yoke prior to disassembly, then torque the nut to 1/16" past the match marks during reassembly.

Probably makes more sense when you look at the exploded view:



Beats the hell out of pulling the diff out...

Thanks for picture. I watched a YouTube video showing the procedure and that looks easy enough. I have a set of FSM's on the wish list. I thought the Mrs might have bought me a set for Father's Day after the debacle with the air shocks, but it didn't happen. The leak isn't bad enough yet that I've seen any spots in the driveway. Just trying to stay ahead of things.

The math of a gear swap works out that 3rd gear with 2.56 is about to what overdrive with 3.73's is on the interstate. I like it. It's really like to see what low gear and deeper gears would do. There was a Caprice wagon with 3.23 in the junkyard this past winter, but I didn't feel like pulling it out in the snow. Of course it's gone now. I'll keep looking and rebuild one at my own pace eventually.

The 4L60E has a 4th gear or “Overdrive” ratio of  .696. This means that with a 2.56 “rear” ratio, the final drive is 2.56 X .696 = 1.78.  3.73 X .696 = 2.6 (very close to 2.56).
I’m constantly impressed how well the LT1 with it’s very flat torque curve, pulls a heavy station wagon with such a high final drive ratio!

To my question: I’m going to have to replace the pinion seal in my ’95 Wagon, and will follow the procedure shown on YouTube, and “scribe” the nut, pinion, and flange. I have a ¾ in. impact, so I shouldn’t need to hold the companion flange. Does anyone know offhand if the pinion nut used on a ’95 Roady wagon (with 8.5 inch ring gear) is 1-1/4? I’m thinking that metric sizes were not used ‘till later years.

You don't need to do the crush sleeve. I did the Delco updated yoke kit on my wagon and it ran fine for a a few years after the install. Fixed the leak, no vibes.

I didn’t anticipate replacing the crush sleeve. The procedure is to mark the nut on the pinion, and then realign the marks, repositioning everything as removed, excepting to tighten the nut a “tad” more (to compensate for wear), then check the rotation of the assembly by hand.
I also had not planned to replace the yoke unless I find a groove worn in it. In checking around, I cannot find any info on a Delco updated kit. The most common replacement yokes seem to be Dorman, which isn’t my favorite brand.
Any further info?

I believe the nut is 32mm. It will be relatively loose, so you do not need a lot of effort to remove it. I was surprised at how easy it was to take off. You do not need an impact to remove it.

By first hand experience, I'll say the nut can be very, very tight. Depends on the case, I guess.