Finished my posi install

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Was feeling a little hypomanic last night after work and stayed up late to finish the positrack install on my truck. Eaton discontinued this particular posi application a couple of years ago but I scored a brand new old stock for a ridiculous price. Part number Q19627-010, and the clutches are rebuildable as they interchange with existing applications. New timken carrier bearings installed as well.

Ran into a few snags, mostly that I had to reshim as it was simply TOO TIGHT to even get the originals back in place. Ended up with roughly 0.030" less shim stack on each side. My adjustable shims minimum change was 0.006" per shim, and frankly that seems a little high. Got to the point where any thicker was simply too tight again and showed 0.000" backlash with a very tight carrier rotation. Stepping back 0.006in on the ring gear side only resulted in 0.006in of backlash with smooth carrier rotation, but the shims could at that point be pressed in by hand pressure only. I'm only very minorly concerned about this as the backlash was significantly higher before torquing the bearing caps so I figure that tightned everything up. I could not produce ANY end play on the carrier measuring with my dial indicator.

Not terribly thrilled with the coasting tooth pattern, but really both drive and coast is very close to the originals. What do you guys think?


Before:








After:






 
Best I can tell, that's indicating that backlash is a bit tight, which it is. 0.006in which is 4/1000 tight. But I've seen a lot of people say with new bearings this opens up some, and 0.004" definitelly isn't a lot
 
Originally Posted By: buck91
Best I can tell, that's indicating that backlash is a bit tight, which it is. 0.006in which is 4/1000 tight. But I've seen a lot of people say with new bearings this opens up some, and 0.004" definitelly isn't a lot

Originally Posted By: buck91
I could not produce ANY end play on the carrier measuring with my dial indicator.


0.006 inch is a bit tight , but I believe it should be fine.
Are you not concerned about lack of end play?

The contact pattern should be acceptable , I suppose.
 
Originally Posted By: zeng
Originally Posted By: buck91
Best I can tell, that's indicating that backlash is a bit tight, which it is. 0.006in which is 4/1000 tight. But I've seen a lot of people say with new bearings this opens up some, and 0.004" definitelly isn't a lot

Originally Posted By: buck91
I could not produce ANY end play on the carrier measuring with my dial indicator.


0.006 inch is a bit tight , but I believe it should be fine.
Are you not concerned about lack of end play?

The contact pattern should be acceptable , I suppose.



By end play I mean lateral movement of the carrier (if present would indicate extreme lack of bearing preload). My biggest concern is that I didn't shim up enough preload, but like I said adding even one more of my thinnest shims made everything too tight
21.gif
 
This is one of the things that a differential shop should do. I think it cost my brother less than $200 to have his front axle put back together with supplied parts. My brother did it the first time and screwed up.
 
Originally Posted By: buck91
Originally Posted By: zeng
Originally Posted By: buck91
I could not produce ANY end play on the carrier measuring with my dial indicator.


0.006 inch is a bit tight , but I believe it should be fine.
Are you not concerned about lack of end play?

The contact pattern should be acceptable , I suppose.



By end play I mean lateral movement of the carrier (if present would indicate extreme lack of bearing preload). My biggest concern is that I didn't shim up enough preload, but like I said adding even one more of my thinnest shims made everything too tight
21.gif



Were there other shim sizes of progressively thicker like 0.008 inch, 0.010 inch etc ..... it can't be all are 0.006 inch only right?
 
So there where three thicker shims- Don't have the measurements off hand. Each outter shim was thicker (to make the sandwich), plus one extra thick shim to use in the middle and a bunch of 0.006 inchers.

I'm going to run it for now and see if it stays quiet. No drone or whine, no clunks, or other noises. In fact, I was surprised just how smooth and quiet everything was right from the start since its a brand new posi with zero miles on the clutches.
 
Originally Posted By: buck91
So there where three thicker shims- Don't have the measurements off hand. Each outter shim was thicker (to make the sandwich), plus one extra thick shim to use in the middle and a bunch of 0.006 inchers.

I'm going to run it for now and see if it stays quiet. No drone or whine, no clunks, or other noises. In fact, I was surprised just how smooth and quiet everything was right from the start since its a brand new posi with zero miles on the clutches.


Monitor it's external housing temperature from time to time ....
by infrared gun or finger/palm touch (and count in seconds) ..... to ensure it's warm to touch and not burning hot.
blush.gif
 
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