Believe it or not most pinion gears have a required average depth printed on the end of the gear. There is even a special tool to set this predetermined pinion depth although it is really just to give you the best possible starting point.

So specific gear sets will work with an average specific pinion depth but it's really just to give you a proper starting point so as to help minimize the number of times you need to pull the pinion bearing off the pinion gear in order to add or reduce the required shim thickness in order to achieve the proper pattern on the ring gear.

A new bearing would also change the required thickness of the pinion shim a bit. Some guys will hone out an old bearing so you can remove it easier and then more quickly figure out the pinion depth, although pressing on a new bearing may change the required shim a bit as well.

I hope you have an inch/lb torque wrench to set the pinion preload after getting the pattern correct with the proper amount of lash etc.

 

Using the original shim thickness is recommended. You don't have to use the original shim, just measure the thickness and use new shims that are the same total thickness. You have to start somewhere, and this is the best place to start.

I would never use the old bearing. I always install the new bearing races and use the new bearings when setting the pinion depth. You will need a press and a bearing separator to remove and install the bearing several times for shim changes. Use gear oil on the bearings when setting the bearing preload. Don't use the crush spacer until the final assembly. Use the old pinion nut for all trial assemblies.

 

For me, the worst part of setting up a gear is crushing the crush sleeve. I went to using spacers, and love it. It helps if you have to change yokes, or seal also.

 

Well... What do we all think?

 

I think from what I can see it's very nice. I'd like to see it with just a little gear oil added to the teeth so that it wipes a cleaner spot on the gear. Did you use an axle to turn it?

 

No I just turned the yoke. I think if anything I need to reduce the pinion shim by a few thou. Of course it all changes when I put the new bearings on. Poke and hope!

 

Try putting a little gear oil on it and turn it with an axle about 5 or 6 full turns in both directions. Don't change anything until you do this. Then see how it looks.

 

Here is the final (I think) set up. This is with the new pinion bearing and shims installed and the carrier bearings and shims installed. Backlash is about .005. Wear patter looks good to me. A bit towards the inner toe on the drive side and very even on the cost side. Good??

 

If this is a Yukon gear then the backlash is way too tight. What backlash is recommended by the manufacturer?

 

Its a Yukon. I took a shim out. Have it at about .007 now. Still getting a little bias towards the toe on the drive side and heel on the coast side. Think I need to reduce the pinion shim a few thou

 

Take .002 out of the pinion shim and set the backlash to about .009.

 

well guys - I hate to revive an old thread... but I have to. I though I had this differential pretty well set up last year. It howled a bit, but wasn't too bad. Plus I figured after I put in my 498 stroker and 3" exhaust I wouldn't notice it which was true. There's probably about 1000 miles on it now however and in recent days the howling got loud. Really loud. It was bad on the acceleration AND on the coast.

So I opened her up and started inspecting things. Ring and pinion teeth look good. Nothing broken or obviously worn badly. lots of very fine metal particulate in the fluid, but nothing I wouldn't expect after breaking in new parts. I checked the back lash and it was way too much. about .022. I added more shims to the driver side move the ring gear closer to the pinion gear. Got the backlash to about .006 - .008. checked the gear pattern with some white grease and it doesn't look good. heavy contact on the toe of the drive side. I suspect the pinion is too shallow. I put it back together anyway and filled it with new fluid. Took it for a test drive and it whines even worse on the acceleration now. not much whine on the deceleration (only a bit as you come to a near stop). So I ordered a new pinion bearing, some new shims, a new crush sleeve, and some marking compound and I'm gonna try this again. With 1000 miles on this ring and pinion, do you think i may have lapped them so they whine no matter what I do? Any advice would be appreciated!

 

I'm very sorry to hear about this. You had it looking pretty good. Did you have all of the bearings completely seated when you pressed them on? That's the only thing I can think of that would have allowed the backlash to increase so much.

 

What was the total shim thickness? It should be close to .484". These 12 bolts tend to open up a bit after you drive them which is why I set them up on the tighter side.

 

Thanks gents.

I am now quite convinced that I did not have enough pinion bearing pre-load when I finished up the job. That would explain the howling sounds, the fact that it has gotten worse, and the "erratic" gear patterns. I suspect this is the case because (stupid me) I packed my pinion bearings with lithium grease. I am sure this caused a ton of drag and threw off my pre-load readings. I'm going to try tightening it up just to see if it fixes the noise. But I already ordered new bearings, races, and a seal. Gonna get this right!

Dave

 

So here is what I found. I took the rear end apart and noticed that the shims on the passenger side of the carrier bearings had slipped partially out. The only thing that was holding them in place I assume was the axle. The backlash between the ring and pinion was .025, whereas when I set it up a year ago the backlash was .007. Also, there was ZERO measurable pinion bearing pre-load. So I pulled it all out. I pulled the pinion bearing and re-shimmed it. I made it .002 less than it was because I suspected the pinion was too deep. I put on new front and rear pinion bearings and a new pinion oil seal and pinion nut. I installed the pinion shaft with a new crush sleeve and got 20-25 inch pounds of pre-load. I spent hours getting the backlash right. Finally got it a backlash of .010 with a total shim thickness of .484. The gear pattern is OK. I'm not overly thrilled but I left it. More toe contact on each side (drive and coast), and a bit biased towards the face of the gear on the coast side.

Put it all back together, filled it with new gear oil, and drove it. NO DIFFERENCE. Howls like crazy on the acceleration and whirs on the coast especially when rolling to a stop. How could I change the Pinion bearings, pinion bearing pre-load, backlash, and gear pattern and have NO DIFFERENCE? I'm not saying it should have been 100% better, but with all those changes, something should have CHANGED.

SO, my theory is that the carrier bearing on the passenger side where those shims had slid out is toast. i did not replace the carrier bearings (they were new a year ago). Maybe since the shims had popped partly out allowed the race to get cock-eyed and it fried the bearing? Or could it be that the ring and pinion gears are worn badly due to the improper set up prior? I hesitate to believe the latter because: 1 - this LOUD howling sound started happening basically overnight. It didn't get gradually louder over time that I noticed (though I do have loud exhaust). 2 - I only had about 1000 miles on the ring and pinion.

See attached image of the carrier bearing shims that had slipped out.

What do we think guys?

THANKS!

Dave

 

How tight was the carrier initially? Maybe there was not enough carrier preload allowing it to loosen up and move away from the pinion increasing the backlash?

 

Slowmo, that is exactly what I think. Probably did not have enough carrier preload before. The key question is have i damaged the gears or is the noise a bearing.

 

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You should be able to spot a bad bearing, the noise on drive and coast is usually caused by too much backlash/changing backlash, caused by a worn pinion bearing, allowing the pinion to move around.
A carrier side bearing noise would be a consistent roar.

How easy did the carrier come out? Any dimples on those gears will make some noise.

 

slowmo - the pinion bearings are new now and pre-load is correct. But it was not correct before and I know my backlash was way too high. I suspect the carrier preload was way light also, which is why the shims were walking out on the passenger side. Its all tight and proper now, but the noise persists. And yes, the noise changes with load (drive) and unload (coast) So could the ring and pinion gears be worn / lapped badly due to the previous improper set up? I am starting to fear this is the most likely scenario.

Dave

 

It's very possible the gear faces are causing the noise, the problem is getting a good pinion depth reading from the maligned teeth. If all is set properly, you may be able to run it and reset the backlash again as they lap together, but that will affect the pinion depth as well.

 

I'd say that the gear is probably bad at this point. Seems like you have done all that you can with it.

 

thanks so much for your input, guys. At least I can say I have learned a lot

 

I believe I ended up at .490" before I felt I had enough preload on the carrier. Worn parts etc. often requires more than the minimum of .484"