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Rear diff question

Chebbyfan

Chebbyfan

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i need to replace the rear pinion seal in my blazer, and I've been looking to see how others do it. I don't see any reason why replacing the seal would be an issue, but one of the "old guy" mechanics in my town says I should do a crush sleeve and seal, not just the seal. Says I'll be replacing t he rearend shortly after if not doing the crush sleeve too. Can somebody help me make a decision on which way to go? Its and 87 K5, 80k on the odometer, 3.08 gears and 33 inch rubber. Its not that I can't fix it, i just dont want to try to crush another sleeve and get things too loose or too tight, as I know that will take the rearend out for sure.
 
I've heard the same. The thought is that you'll never be able to match your pinion preload so it'll either be too tight or too loose.

So here's the easiest solution. Use a punch, chisel, or paint pen and mark the location of the pinion nut and pinion. From there, remove the nut and count the rotations it takes to remove it. This will allow you to get extremely close to the original preload after you've replaced the seal and reinstalled the nut. Add some loctite too. You'll be able to knock this out in thirty minutes. There used to be a good YouTube video on this. Oh and a foot long 2x4 with a big hole in it makes installing the seal a piece of cake.

Quick side note, if you ever rebuild the axle assembly, use a crush sleeve eliminator kit. Crush sleeves are for the birds.
 
I would replace just the seal, if it was mine. With low mileage such as that, I would check for any play in the bearings, then proceed if they are tight.
The trick is getting the nut back on tight enough without going too far, obviously.
I would reuse the original nut because marking it's position against the yoke can be a small guide. The resistance to turning it will be similar going back on to give an idea of how tight to take it going back.
I would use red loctite going together as if I had to go back into it, heating the nut is not a problem.
 
The crush sleeve is there to set the pinion bearing preload, which can't be done with the carrier in the housing. I you did do the crush sleeve you would need to pop the carrier out, so you measure the actual preload.

replacing the pinion nut after doing a new seal is all about feel and technique. which is incredibly hard for me to describe how I do it on line. It all come down to trying to put the pinion nut back exactly where it was before.

Some axles can use shims to eliminate the crush sleeve, I have them in 2 14bff and a front d44. If I need to swap a seal no problem just torque to spec and go.
https://www.yukongear.com/shop/sk-csgm8-5# you still need to set this up by checking the preload rotation w/o the carrier installed

Before you replace the seal check your axle vent, if it is plugged even a new seal will leak.
 
The right way to do it is to use the new crush sleeve that comes with the axle overhaul kit that you get with the 4.56 gearset.

But since that wasn't the question, I would say to research this topic here and come up with what's the closest thing to a correct torque spec to reset the pinion nut. There is a giant torque spec to start the crush of the sleeve, but this is going to be a much more reasonable number that gets everything tight enough, without collapsing the crush sleeve any further.

I don't think there's an "official" procedure to swap the seal only, but it seems like somebody unfamiliar with setting up differentials could be more likely to screw things up pulling the carrier and replacing the crush sleeve than trying to reset a good factory setup. Do be sure to check on it a few times for any signs of loosening.
 
Also, reusing a pinion nut comes with its own set of potential drawbacks - they are intended to be a one time use item. There’s a reason they are internally tapered or dimpled threads when new.

Plenty of “McGuyver” type methods out there and if done well enough will last for a while but none are as secure as a fresh sleeve ( or eliminator ) and inch pound rotation verification with a new nut.
Some make a try at it and it last 30K and they think that was a success - some do the same on a front axle and “think” it was a success because it “worked” but in reality the front axle never racked up many actual miles.

All comes down to McGyver type skills and/or what you call “good-to-go” or “good enough” or if ya are a verified it’s as it should be type of repair wrench turner.
 
tarussell said:
Also, reusing a pinion nut comes with its own set of potential drawbacks - they are intended to be a one time use item. There’s a reason they are internally tapered or dimpled threads when new.

Plenty of “McGuyver” type methods out there and if done well enough will last for a while but none are as secure as a fresh sleeve ( or eliminator ) and inch pound rotation verification with a new nut.
Some make a try at it and it last 30K and they think that was a success - some do the same on a front axle and “think” it was a success because it “worked” but in reality the front axle never racked up many actual miles.

All comes down to McGyver type skills and/or what you call “good-to-go” or “good enough” or if ya are a verified it’s as it should be type of repair wrench turner.
Click to expand...
True, and I understand your point, but I have had to deal with more than one loose, factory installed nut on Eaton 18 speeds, Mack 18 speeds and Meritor 46K rear axles. Many with less than 50K miles. Usually find them when greasing the drive shafts during a service. And usually need the truck to run the next day.
Which is why someone taught me to use a good amount of red loctite on clean threads.
Dump trucks, mixer trucks and heavy haul trucks are hard on things..
 
6872xtc said:
I would replace just the seal, if it was mine. With low mileage such as that, I would check for any play in the bearings, then proceed if they are tight.
The trick is getting the nut back on tight enough without going too far, obviously.
I would reuse the original nut because marking it's position against the yoke can be a small guide. The resistance to turning it will be similar going back on to give an idea of how tight to take it going back.
I would use red loctite going together as if I had to go back into it, heating the nut is not a problem.
Click to expand...


All of this. We've done hundreds in the shop when I was young, on everything from fleet trucks to standard pickups. Just make sure to scribe the nut and pinion good so you know where to put it back to. Clean the threads like was said and don't worry about it. Hell my current dmax has had another 150k put on it after I did mine. I suppose though if I was a billing man I'd be telling the customer I need to rip it apart and crush sleeve it, but that conversation is for another thread.
 
This is one of those things where its good to overthink, but don't over think it too much. As others have said, yes you should use a new nut, however I have done as others and been just fine. If possible the best way is to remove the carrier and use an inch pound torque wrench to get rotational torque and set it back to that. Marking the nut is great but I've seen guys mess that up or go an extra turn to get the marks lined up (don't forget those marks will line up multiple times).

This is one of the reasons I like Dana axles better, shims not crush sleeves.
 
When my seal went bad I simply used a punch to mark the nut and the diff nose and counted the turns it took to take it off then turned it the same amount of turns going back on aligning the marks at the end.

Done it like that for years and have never had a problem.
 
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