The only proper way to set up the pinion bearings is with a new crush sleeve and by tightening (crushing) the bearing inner races till the bearings are tight to an exact amount 10-15inlbs if I remember correctly. This is the force to spin slowly the pinion without the ring gear installed. Just the drag of the tightened bearings.
A proper set-up would then measure pinion depth and everything would be taken back apart and the depth altered by shimming.
Next the carrier preload would be determined and the carrier installed for back lash measurement. I would not vary back lash by change pinion depth. I would do it by moving the carrier side to side with shims.
In practice these methods are very seldom used. Proper pinion depth tools cost thousands of dollars and are differential specific. The original set up is usually used with the proper bearing set-up and a white lead or prussian blue contact pattern is taken and read. Gross errors in pinion depth are corrected otherwise its accepted and backlash is corrected.
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician
[This message has been edited by stevebfl (edited 03-29-2000).]