Raiph

I'm building my first rear end, it's an 8.5" 10 bolt. New Detroit TrueTrac and new Yukon 3.73 ring and pinion. Backlash measures .007-.008 across multiple teeth on the ring gear. Can anyone's more calibrated eyeballs give me a suggestion if this is an acceptable pattern or do I need to change the pinion shim? Thanks.
Drive side:

Coast side:

sofakingdom

iTrader: (1)

Looks reasonably ballpark-ish to me. Pinion might be a .001" or 2 on the deep side maybe, but not seriously enough to warrant tearing it all down and starting over.

What pinion shim is in it now?

Not a thirdgen Camaro/Firebird, is it?

big gear head

I agree that the pinion might be just a little bit deep. What have you tried? Also, you might try opening up the backlash a little to see if the pattern will move away from the toe a little bit.

Raiph

You caught me on that one. It's out of a mid 70's nova and going into my 68 Camaro. I'm using a .025" shim now. My pinion shim kit only has shims in increments of .005". Thanks for your input, puts my mind at ease.

Raiph

I've tried, the .035 shim from the original pinion and .025, .020 and .015. That one looked the best to me. When you say open the backlash do you mean by about .001-.002 or more than that even?

big gear head

Most of the Yukon gears that I installed had a higher backlash spec than most other gears. Check the spec for yours and see if it's closer to .010. I've seen some Yukon gears that called for as much as .014. Open it up some and see what happens to the pattern.