Continuing the saga of
The NeverEnding Story: 2001 1500 4x4 9.25 Rear Axle: Pinion Seal & Bearings
The NeverEnding Story II: 2001 1500 4x4 9.25 Rear Axle: Pinion Nut
...

Old pinion & carrier.
New bearings on both.
Old pinion spacer/shim.

I installed the pinion with new crush sleeve so that it has no front/back play, and torqued the rotation to ~22 (+/- a few) in-lbs each way (specs say 15-35 in-lbs for new bearings).

I installed the carrier and - after much weeping & gnashing of teeth - got the backlash within spec, the bearing cap bolts & bearing adjuster nuts torqued, and the adjuster locks installed.

Next (according to service manual) is gear contact pattern, so I painted both sides of 4 ring gear teeth, wrapped a shop towel as best I could around the pinion yoke for resistance, and rotated the ring gear in both directions.

Wowzers is it way off!

Results:

• I could find no discernible pattern on the drive side, but can see some paint on the drive side of teeth that I had not painted just on the very inside edge [see pics below]. I don't know, though, from which direction of rotation that paint got put on there.
• The pattern on the coast side is way outside [see pics below].

Keeping in mind that this whole project is my first time inside a differential to do anything besides changing gear oil, my questions are as follows:

• Would new bearings on old pinion & carrier with the old shim really be that far off of pattern?
• If not, any clues as to what I did wrong?
• If so, does that mean I need to redo all of this using a different thickness pinion shim?

The pattern appears to be an extreme version of this, which would indicate that I need a thinner shim....

I thought I was doing well to get to this point without (seemingly) majorly screwing anything up, and to be honest I was quite deflated when I saw my pattern. So I haven't touched it in a few weeks. But I need to get back to it and need some direction from folks who have been there before.

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Drive side - focused on painted teeth


Drive side - focused on non-painted teeth that got paint on them


Coast side

 

Just in case it might help, here are three pics (I cropped & zoomed and rotated to line them up as best I could) of where the pinion & ring gear teeth meet. I took 3 successive shots as I rotated the pinion just a little:

 

Heel to toe doesn't really matter, you're just looking for crown to root. I'm not seeing much with your pattern. Cut your marking compound w gear oil - just mix it on some cardboard or in a small dish like you would JB weld.

You may need to spin the pinion some more, too. I know you said you provided resistance which is good.

If you truly put everything back together exactly as it came off then, no, I can't see your pattern being THAT far out. Worst case I might just run it and see if it's quiet -- again, assuming all shims were placed back in original locations.

 

Oh, also in reading your procedure more closely, place drag on the carrier or even the OD of the ring gear and turn the pinion. Some guys will put a drill on the pinion nut and run it around several times while providing resistance to the carrier

 

I think this is a large part of the problem right here. Need to use the pinion to turn things, to get an accurate pattern.

 

That's what I get for following the destructions:

I'll do it the way y'all suggest the next chance I have to go out and work on her.

Thanks again!

 

The first thing you learn in the world of differentials and gear setup is that things are rarely done by the book. Everyone is aiming for a good pattern but how they get there varies.

Other times values (or at least tolerance ranges) are almost ignored as guys have learned that a certain diff prefers minimal backlash or pinion bearing preload at the high end or low end.

Regardless, you've gotta try for a better pattern so there's information to draw a conclusion. There are FB groups just for gear setup where you can post your pattern and questions, too. It's at least 50% art and 50% science

 

UPDATE

I wiped off the old compound, cut some with gear oil and applied, added some resistance to the ring gear with a rubber mallet (I'm not sure the best way to provide drag without damaging the ring), and turned the pinion companion flange (by hand). The pattern looks the same as I posted above.

I think at this point, since The Boss has told me that I have to have it moved by this weekend for a yard sale, and I have to work for a living so can't take all week to work on it, I'm going to do as Keith mentioned and just put the rest back together today (axle shafts, diff center pin; new wheel bearings & seals), fill it with gear oil, give it a test run, and see what happens.... Wish me luck!

 

Looking at the pattern, I would think the pinion is set too deep.... you are only catching the outer edge of the ring gear teeth....

 

That is what seemed logical to me, too; but - as I stated initially - seeing as this is my first time I had to watch videos. Everybody who put new bearings on old pinion & carrier re-used the shim (which I also did), and either had no problem getting a pattern, didn't show it & didn't talk about it, or didn't even do a pattern check.

So to re-ask a question: Would new bearings on old pinion & carrier with the old shim really be that far off of pattern?