mrbigg,

There are two different pinion installations that are commonly used....shims and crush sleeves. The shim style setup sets the pinion depth (relative to the ring gear) by using shims....if you tighten the pinion nut too tight, just right, or not quite enough, the pinion depth stays the same because the shims are setting the spacing.

For the crush sleeve method, instead of shims, there is a tube that "crushes" or collapses as you tighten the pinion nut...if you go too far, the crush sleeve becomes too short and allows end play on the pinion. The crush sleeve was invented to allow easier setup at the factory since they dont have to measure, remove the pinion, add shims, reassemble, etc. Instead, they torque the pinion nut until the proper pinion depth is met.

Unfortunately, a Chev has a crush sleeve. Unfortunately, making a mark on the nut doesnt work since the nut is a deformed thread nut and is usually replaced with a new nut. I know someone (very close to me) who has reused the nut by first scribing the witness mark on the nut and the pinion (not the housing!!) and disassembled the nut. After replacing the seal, the nut was replaced and the marks aligned. I....er he, used Loctite to assure the nut stayed tight.

If you use a hand wrench instead of an impact, there is no danger of hurting the teeth...if you can put constant pressure on the nut with an 18" breaker bar and your arms, you cant hurt the gears...at least a normal person cant.

If in doubt, ask for a quote from the Chev dealer to replace the seal....

mike in tucson