So I have my diff out because I've got the rear end apart and of course what better time than now....(budget starting to thin a little) to change the seals...the right side must have been leaking because the whole side was covered in grime. An experienced corvette mechanic checked my yoke in/out movement and said it felt fine. So I figure I just want to change my seals. I was quoted 275 to have it sent out to have seals changed and "reset" or re-torque (I forget which)the pinion. While I think it's not a ton of money, I have a few things on my plate already.
I did a search but haven't found a good answer.
Question: Is it simple enough to pull the cover and remove the c-clips, pull the yokes and change the seals? Car has 50k and been sitting since 97. Is this reset of the pinion important? I am almost tempted to go ahead and spend the 275, especially if it means the unit will come back clean and ready for paint. Also wondering if I should open the case either way so I can see if there's any reason to change the yokes as this could add to the cost and then it would force me to do it myself.
Anyone have a procedure documented, hopefully with some pics?

 

If you're just changing the yoke seals or yokes and seals, there's no reason to touch the pinion setting at all. Might do more harm than good actually.

 

Just changing the yoke seals is hardly worth $275. Might be $40 worth of parts with the lube and if I really tried I might be able to drag it out for an hour by the time I clean up the gasket surface and refill the diff. If you're doing the pinion seal as well, it might be worth paying someone to do it if you don't have the tools. There's a lot of torque on that pinion nut. You need a couple of special tools to do it, and its a pain.

 

so....pull the cover off, pull the clips, pull the yokes out, pry the seal off and tap in a new one....put yokes and clips back...close the cover and refill? And then there's the front seal.....how tough it is it and what are the tools?

 

Only tool you need for the front seal is an impact wrench.

1) Mark the nut and pinion.
2) Remove nut with impact.
3) Pull yoke off.
4) Replace seal.
5) Reinstall yoke.
6) Tighten nut in short bursts with the impact until the marks you made in step 1 line up.

 

Soooooo...I assume you mean the nut and the end of whatever the nut is screwed onto (Hope I don't seem stoopid but just want to be sure) which is the pinion right?
If there is supposed to be 300lbs torque then do I assume my humble impact wrench will be able to remove it....I do have the unit out of the car so does this mean the side yokes will turn and I have to somehow hold those? And then when I re-assemble it lining up the mark means I reached the same torque as it was when I pulled it off?
And the selas just pry off and tap back on? Thanks guys.....

 

don't be surprised if the side yokes don't come out as easy as people are saying, they will likely be a tiny bit "mushroomed" on the clip ends (most are). you can still get them out but it takes a bit of work, they will move about a 1/2" then stop dead, you'll swear that there is something holding them in place but once the C-clips are off there is nothing left holding them in except the "mushroomed" ends.

 

Yes. Mark the pinion nut to the pinion shaft.

You need a decent quality 1/2" impact. You can hold the side yokes with your hand, the impact (and inertia) does the job.

Yep.

 

So I guess the next question is how much mushrooming is ok....and will these suckers go back in (could it be the removal "de-mushrooms" them)?
....if they are sticking on the way out I suppose I just pound them (gently)?

And what is the socket size I'll need for the impact wrench?

Thanks again

 

Big. I can't remember the exact size but it's over 1". You don't need an impact socket though, a regular one will work.

 

I don't remember the size of the nut but you'll figure that out pretty quick. My impact won't remove the pinion nut. You need a serious impact wrench for that. I made a tool to hold the yoke from a piece of 1/4" plate steel and a four foot bar. The plate has a hole cut in it for the socket for the pinion nut to go through and four holes for bolts to bolt it to the yoke. The bar is welded to it and acts as a long handle to hold the yoke from turning. Then you use a socket on a long L-handle with another four foot bar over it. With this arrangement I can generate enough torque to get the nut off. Once you've done that the rest is easy. Just make sure you marked the nut and pinion so you can torque it exactly the same as before.

 

A conventional socket will work if you are using the armstrong method, but don't try using a regular socket with an impact wrench. You'll split it wide open, especially with the torque needed for this job. (Ask me how I know this... )

 

I believe it's a 1 1/8" pinion nut.

 

Regular socket on a 1/2" impact worked fine for me.

 

1/2" impact gun and socket worked for me too.

as far as the mushrooming goes, it's so slight you won't even be able to see it, if you try to pull them by hand and they won't move more than 1/4 to 1/2 then it's the mushrooming. I had to use two pry bars on either side of the yoke and pry them out. removing the does remove SOME of the mushrooming but not all, I ended up having to file the ends of each spline in order to get them back in, then I had to CONVINCE them to go back in.

 

To remove front yoke
Use a 1/2" impact with 1 1/8" socket to remove nut after you mark the nut and the end of the pinion with a chisel.
You may need a bearing puller to pull off the yoke if it is frozen. You may need a cold chisel to remove the seal. We do use a chisel for 99% of the ones that have never been off.
Clean all the surfaces thoroughly including the splines.
Use Permatex #2 liberally on the mating surfaces of the seal and the I D of the yoke to prevent leaks. Be sure to clean off the yoke's seal area. Use some red Scotch-Brite and brake clean.
With most of the seals out there now leave 1/8" at the bottom of the seal so the rubber is over the yoke OD properly when installing.
Put a light coat of grease on the yoke seal area also
.
We look for 10 inch pounds on the nut for used bearings. 20 inch pounds one new bearings. The mark will get you close.
Yes it takes 300 foot pounds to torque the crush sleeve originally.
Run a tap into the u-joint bearing cap holes if you have one (C 3's, 5/16 - 24)

When removing and installing rear cover clean surfaces well and use a new gasket with #2 Permatex on both side of the gasket.

Removing the stub axles to replace the side seals.
Use of course snap ring pliers. If the axles are mushroomed badly just stop and go have your differential rebuilt as all the shaving have gone through the bearing and R & P. If the stub axles are good pull them out.
The seals pry out easily. Clean mating surfaces.
Use the Permatex again on the seals mating surfaces. Clean and lightly grease the stub axle OD's seal area.

 

An experienced mechanic told me once that, generally, a seal doesn't just fail all by itself. Usually, first the bearing begins to wear, and then the excessive runout caused by the failing bearing becomes more than the seal is designed to tolerate, and then the seal starts to to leak.
I imagine a failing ujoint next to the yoke could cause that problem, as well.

 

The right hand side (passenger side) of my differential is also coated with sludge. The seals are fine. The oil plug is leaking. Just in case.

 

I've had to replace the front (pinion yoke) on rear ends several times over the years to change from the small front yoke (68 and older) to the big yoke. Marking the yoke and pinion is ok, unless you tend to clean and paint when taking stuff apart (doh!). The idea of this exercise is not to crush the pinion bearing sleeve any more than it already is, thus maintaining the pinion depth setting. A simple trick to get the nut tightened back to the right torque with no more crush -

Set your impact on the lightest "hit" that will still move the nut on the yoke. Run the nut on (slowly), wiggling the yoke to feel for play. At the same time the play is all gone, the impact will stop making progress since the crush sleeve is up against bearing and yoke and it will be back to the setting it is supposed to be. Using the lightest setting on the impact will allow it to stop and not crush the sleeve any more.

As I said, I've used this method several times and never had any problems with noise, etc when using the rear afterwards.

Good luck.

 

Simplest way I've ever seen it described. Well done