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Pinion Seal / Yoke Removal

Chief Brody

Chief Brody

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Looks like I need to remove the yoke and replace the pinion seal on the Blazer...12 bolt GM Corp 8.875...
any tips on doing this in the driveway...would be easier on a lift...but...
:dunno:
 
anybody done this recently? Did you need a puller to get the yoke off?
 
Chief Brody said:
anybody done this recently? Did you need a puller to get the yoke off?
Click to expand...


Yah I just swapped my ten bolt yoke for a 14bsf yoke to run my new driveshaft so I didn't need a conversion joint. It just came off with a few light hits of a hammer.
 
if the other end of the drive shaft comes out of the transmission will the fluid run out?
 
Sometimes the yoke just slides off and sometimes it needs help, luck of the draw.

Don't forget that diff uses a crush sleeve and by taking the yoke off you lost the pinion bearing preload. LOTS of debate on if putting it back the "wrong" way is reliable or not, the "right" way involves complete disassembly of the diff.
 
38377k5 said:
Sometimes the yoke just slides off and sometimes it needs help, luck of the draw.

Don't forget that diff uses a crush sleeve and by taking the yoke off you lost the pinion bearing preload. LOTS of debate on if putting it back the "wrong" way is reliable or not, the "right" way involves complete disassembly of the diff.
Click to expand...

you had to go and complicate it didn't you....

I saw the 1A Auto guy put it back on with an impact wrench
 
Big no on the impact gun.

1 Use a small chisel. Mark the pinion face. Then mark the nut. Note the relationship just in case you didn't get the marks lined up perfectly.

2 Remove nut

3 Yoke might slip off. Might need to tap.

4 Replace seal

5 Reinstall yoke and put nut on as far as you can with a small ratchet

6 lock parking brake. Use a long bar to Tighten nut until the marks line back up exactly. Be very careful. A tiny bit past is better than a tiny bit looser. It helps a lot to have a yoke holding tool. But I have seen it done with the brake before.

I have done it this way hundreds of times. Never had an issue. Otherwise you will need to completely disassemble and reset bearing preload
 
1BEATK5 said:
Big no on the impact gun.

1 Use a small chisel. Mark the pinion face. Then mark the nut. Note the relationship just in case you didn't get the marks lined up perfectly.

2 Remove nut

3 Yoke might slip off. Might need to tap.

4 Replace seal

5 Reinstall yoke and put nut on as far as you can with a small ratchet

6 lock parking brake. Use a long bar to Tighten nut until the marks line back up exactly. Be very careful. A tiny bit past is better than a tiny bit looser. It helps a lot to have a yoke holding tool. But I have seen it done with the brake before.

I have done it this way hundreds of times. Never had an issue. Otherwise you will need to completely disassemble and reset bearing preload
Click to expand...

Kind of depends on the impact gun and if the crush sleeve is orginal aftermarket etc.

I have used an impact before with good results but its no hardcore 10 billion foot lbs impact. Just a generic run of the mill impact.

In all reality I haven't come across many diffs that were say 100k old, that didn't need a new crush sleeve in them. With pinion preload occasionally measuring at 2 or 3 inch lbs.

I pretty much would say do as above but I would tighten it just a tick past the mark. Also a pipe wrench on the yoke is a great holder while you are trying to get the nut tight.
 
I've done it on a 12 bolt using the method above. I went a little past the original mark to re-establish a little bearing pre-load. I personally wouldn't use an impact since crush sleeves are technically one time use. If you've ever built a rear end, It can be very hard to get a sleeve to start 'crushin' but once it starts to go, you can over-crush it cery easily resulting in way too much pre-load. Basically, an impact could over-do it which would require you to tear the diff down to replace the crush sleeve and try again.

One more warning, inspect the yoke carefully. If the seal has hardened and worn a ring in the yoke, you'll want to speedi-sleeve it or replace the yoke. Otherwise, it will still leak and you'll be doing it all again. Good luck.
 
When I did mine it was pretty easy. The hardest part was prying out the old seal. In addition to marking the yoke location, I used a machinists rule to measure the threads when tightening the nut. Yes, the is the "wrong" way to do it, but many have had no problems, and you're talking a 30 minute job versus a multiple hour job. If you take your time and don't get crazy on the torque there should be no problems. I used an impact to put it back on, but working gingerly and with short bursts. It seems fine so far.
 
I always use an impact. Never had a problem. I've cranked 'em down real tight on a worn axle before.

Martin
 
82355 said:
I always use an impact. Never had a problem. I've cranked 'em down real tight on a worn axle before.

Martin
Click to expand...

I honestly wonder just how sensitive that bearing is to preload. To hear some people talk if you get it a couple inch-pounds too tight it will self-destruct. I was careful when I put it back because I didn't want trouble, but given the size of the bearing it would seem as long as the yoke is snug and the bearing isn't binding it would do alright. I would think too loose would be of greater concern. Oh well, I don't pretend to know more than the engineers that built it...
 
Buddy just put his 14SF back together, and torqued the nut to 50ft lbs, regardless of what it was before. Said it's not making noise, although I'm not sure thats the best indicator that its "right".

I tend to agree that re-using the crush sleeve must not be a real precise science, because while GM has all sorts of procedures for getting it "right", almost no one does it that way, and there seems to be very few, if any, who have problems, at least in the short term.
 
I used an impact. But I had no idea what i was doing at the time lol.


Seems to be fine regardless
 
Like I said before it depends on your impact.

I have had crush sleeves that stalled a 20 ton press.

I mean your talking axle out on the floor, pipe wrench holding the yoke, me ( near 300 lbs) on a 6 ft long breaker bar. Can't even move the thing. Took a 10 ft breaker bar with me on it. To tighten it we went back to the 6 ft breaker bar

Even my buddys 1000 dollar 3/4" drive snap on impact would not touch it. AFTER we started the crushing

Of course I have had crush sleeves that literally an 1/8 of a turn made em too tight.

Just do it like was said above and tighten the crush sleeve just a tick past your mark.
 
What's the crush sleeve look like and why don't you replace the bearings while your in there? :dunno:
 
Your pinion has two tapered bearings on the shaft. The crush sleeve goes between them and as you tighten down the pinion nut, begins to crush, but as it does, it presses outward - pushing the bearings away from their races.The right amount of crush seats the bearings solidly, but doesn't overload them. Too little and the pinion can bounce back and forth axially. Too much and the bearings will be heavily loaded, get hot, and possibly fail. The 'right' way is a delicate process, but the sleeve can take a lot of force to start crushing. Once it does, the crush zone (swollen out part) can give in quickly. So no impact for me. However, there must be a pretty wide 'butter' zone since so many are using impacts. The 'right' way to measure if you got it right is to put an in-lb torque gauge on the pinion nut and spin the pinion (with no ring/carrier installed) to verify the rotational torque is within a certain amount. I would do this for a rebuild, but not a pinion seal.

Edit: To answer your other question - You can change one bearing (towards truck front) but the rear bearing is inaccesible without a teardown. Same goes for the races for both bearings. Can't drive em out with the pinion in. Also the rear bearing has shims between it and the pinion head that determine the 'pinion depth' when building a rearend and it is pressed on. Don't change the bearings unless you need to.

crush slv.jpg
 
Ditto on going back on with the nut plus 1/16 past where it was
Initially, as it takes up for wear in the bearings.

That's. assuming there is no play in the bearings before you take it apart.
If the bearings are worn that could be cause for the seal to fail. Bad bearings means its got to come apart.

I had a twelve bolt that the nut backed off, it leaked, put new seal and tightened.
Was fine for a long time, wasn't a DD
 
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