Rear end pinion depth, backlash, carrier shims questions..

[mcintyrederek]

Hi,
Doing a complete overhaul of a corporate 10 bolt, 8.5" open carrier, going from a 2.73 to a 3.23 behind a TH400 and mild 350 engine.

I have the necessary tools, like torque wrench, inch-pound wrench for adjusting carrier bearing pre-load, digital caliper and dial indicator.

I've done a lot of research over the past several weeks.  I feel I'm more than capable of setting all of this up but I need clarification on one thing.

The pinion uses shims before the inner bearing, which sets pinion depth.  The carrier also uses shims, which sets the carrier from left to right.  Moving the pinion closer to the carrier (pinion depth) will affect backlash and pattern..  Won't shifting the carrier from left to right do the same thing?

I know the carrier should be tight (not like hammered in tight, but not loose either.)  When installing the carrier, are you aiming for the same shim thickness on both left and right carrier bearings? 

When setting the backlash, if I have too much slop, is the correct method for correcting this to ADD shims to the pinion bearing, or more the carrier slightly one way or another?

Thanks for your thoughts.

[VileZambonie]

You need to set the pinion depth and adjust for the variance etched in the face of the pinion gear. Once you properly preload the bearings and set your rotational torque you will need to install the carrier and achieve the proper backlash with the proper side clearance. You will need a dial indicator and fixture base to perform the appropriate measurements. The next critical step is to check the gear tooth contact pattern. From there you will determine whether or not the pinon needs to be moved. Once the pattern is correct, install the pinion seal, reset turning torque and set your carrier. Perform the final gear tooth contact pattern analysis and you will be good to go.

[mcintyrederek]

Thanks for clearing that up.  I understand what needs to be done but I just didn't know exactly how to achieve it and in what order.

The dial indicator I'm using has a flexible arm with vice-grip type mounting so I should be able to find a good place to mount it.  The way I understand, you measure 90 degrees off the gear on the back (coast side) for backlash.

From everything I've read, 0.060 is the correct number for the GM 10 bolt.

[mcintyrederek]

Excuse me..  I mean 0.006" to 0.010 of backlash.