Gear Pattern - Pinion Depth

[ck1insac]

Hey guys, my first rear end build on my Chevy 12 bolt. My main question is regarding the straight line at the bottom of my gear pattern. I’ve read several threads where it’s an indication of the pinion being too deep. However, adjusting the pinion, I get similar patterns. I’ve gone down to .020 pinion shim. These pics are using a .030 pinion shim and a backlash around .008. This is a new Eaton TruTrac carrier, and new 3.73 Motive Gears. All bearings and races new as well. I’m in no rush and just want to do it right. Any recommendations or insight would be much appreciated.
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[Keith Seymore]

Don't the new gears give a pinion depth number that you are supposed to set it to?

K

[kwmech]

Without seeing the pattern with a 20 shim I'd be inclined to leave it there. Do you have a .025 to toss in there?

[Accelo]

I ground down the I.D. of a bearing set so I could change shims without pressing them on and off. There is little difference between bearings so once it's set I can press the bearings on once. Did you carry the marking paint all the way to the edge of the tooth? It looks like you stopped painting at the outer edge. If it's the pattern hitting you have issues. If it was just lack of paint it looks pretty good to me.

A lot of Videos out there but this is one of my favorites;
https://www.youtube.com/watch?v=nVb5WRUfM7Y

[BigBird05]

It looks a little deep, but you could live with it. Much better that to far out.