Rear Axle Preload/Pinion Yoke Question
 

Alright, so my pinion seal was leaking on my rear axle. I set out to change it. Disassembled everything. Used a puller to get the yoke off, and reassembled. Aligning everything the same as it was. Found out I have a locking G80 diff as well, when I later took off the cover.

When I spin the yoke using one of the wheels, I noticed a slight wobble on the edge of the yoke near the pinion seal. Not sure what to make of that. Do I need a yoke?

I also noticed I have around a 1/4 inch of rotational play in my pinion gear when I turn the yoke. I noticed this prior to disassembling everything as well. I'm wondering if my preload is set wrong. And maybe was set wrong from a previous repair? The u-joints on my drive shaft are marked with a paint pen, from work the previous owner has done or has had done. Not sure if the pinion seal has been done before. I could tell the one I orignally pulled out was orange on the side facing the pinion gear.

Other than the yoke, everything has looked okay so far. I haven't heard any noise from the axle.

I've pulled the cover and noticed some metal on the magnet, but not a crazy amount. Gonna replace with a new cover. Also gonna pull the axles and change the backing plates. Maybe axle seals, although they are not leaking, and gonna refill with fluid. I am just afraid my preload may be wrong, even though I set it up as it was before. Thoughts?

Timken makes high quality seals that are painted orange. Did you replace the pinion bearings? If the smaller bearing by the yoke is worn out a new seal will not last. That could explain the wobble at the yoke and the material on the magnet.

No, didn't replace the pinion bearings. Just pulled the yoke off and changed the seal and put it back on. Thats when I noticed when I turn the yoke, there is a wobble in it, by the pinion seal, almost like the metal on it is bent.

I will make a video.

Backlash between ring/pinion is almost imperceptible by eye (around 0.008") as measured on the ring gear (less if 2-cut gears). Pinion depth is controlled by shims under the pinion. Pinion preload is controlled by a crush washer.

Better figure out if the 1/4" play you speak of is between the pinion gear and the ring gear, or if it is in the spider gears/side gears themselves. Bet the play you are seeing is there. If not, your ring/pinion is not long for this world!

Per factory manual - before removing yoke, you test the force required to constantly rotate the assembly using a 1/4" drive beam or dial indicator type torque wrench that reads inch.lbs. Yes, you have to adapt them to the 1 1/4" socket. Then when you are done you tighten the pinion nut to crush the washer slightly more to get maybe 5 in.lb more than originally tested. This will take several hundred ft.lb of torque and something to hold the yoke from turning.

Or another strategy is to mark the pinion nut before disassembly and try to tighten it to match exactly the original position.

Or some people get lucky and just tighten the pinion nut to a couple hundred ft.lb with an air impact, assuming that will not crush the crush washer any more - maybe true! At this point this seems your best bet. How did you hold the pinion from turning when you tightened the nut? How tight did you get it?

good luck - if you have specific questions please ask.

Thank you for the post - Much appreciated.

I used an impact gun, and tightened the pinion nut with that till it matched the marks I had made. The impacting kept the yoke from turning. All my marks matched up.

I just tried to take the bolt holding in the c clip retention pin out, and my crappy sockets just kept rounding out. Epic fail.. I guess I will just cut my new backing plates enough to slip them over the axle. My axle seals are not leaking either, so I guess this will work.

I also noticed it appears my yoke is out of round.
It also seems it may be a little far from the pinion seal, but I have tightened it the same as when it was before I took it off. Looking at a Jimmy at the junkyard, it's yoke definitely seemed closer to the pinion seal.

I tried to check for play on my truck by moving the yoke up and down, and side to side. I didnt find any there.

I checked for play between my pinion and ring gear, and there is a very slight amount.

The locking diff is werid. If I turn the yoke, it acts like an open diff. I I turn one of the axles, it just turns and turns with out spinning the yoke , and then it will lock and both axles spin the same direction.

I will put everything back together and fill with fresh fluid and see where I am at. Might take it to a local ring and pinion place. And have them inspect it, and fix any issues.

Here are some pictures of the diff.

https://cimg1.ibsrv.net/gimg/blazerf...bcd6a44790.jpg
https://cimg2.ibsrv.net/gimg/blazerf...a5659b9a3f.jpg
https://cimg0.ibsrv.net/gimg/blazerf...e2f81ed1c3.jpg

That "wobble" is just in the dust shield. It won't hurt anything. The 1/4" of play at the yoke is normal, too.

That is kinda my thinking on it too.

Got the diff resealed, and filled up with fluid.

Broke a brake line! Doh.... Oh well, at least now I will get all the old fluid out now haha.

Gonna get this wrapped up tomorrow after work hopefully.

Nice photos!

As I understand the Gov-Lock rears - they do nothing unless one axle spins enough faster than the other axle that a centrifugal weight throws out a cog and the two axles lock together. No prevention of wheel slip, just sudden locking of the axles after excessive wheel slip has already occurred. This is why they are lovingly called Gov-bombs. Do this when you make some real power and they explode! Not good rear ends for people who like to spin their tires to impress their friends.

The G80 Gov Lock is considered a Low Speed Traction device. I installed a G80 in my 89 S15 Jimmy and it works as intended. But it is not meant for hot rodding. A delta of 100 RPM is all it takes to lock the axles together and over 15 or 20 MPH the axles unlock. It is a true locker at low speeds. There are some good you tube videos illustrating how the G80 performs in different conditions.

When I installed the G80 I had to replace the ring & pinion gear due to carrier breaks. My crush sleeve had split and the pinion bearings were worn. I installed new crush sleeve, new pinion bearings, new carrier bearings and new axle bearings. The only way I was able to wrench the crush bearing was to use my impact gun a little at a time and check the rotational torque after each little hit with the impact gun. I was able to get the torque value right at 26 inch pounds. (I did set pinion depth, backlash and checked gear tooth pattern)