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I'm getting ready to start assembly of my 489 case diff. I have the solid spacer/shims for setting pinion bearing preload. Is this something I can do first, since I may have to trial and error the pinion depth a bit to get it right? Will dis-assembly to change the pinion depth shims impact the pinion bearing preload once I have that where I want it???

Or is it better to make sure the pinion depth is correct before attempting to figure out the shim pack for pinion bearing preload?



The pinion preload will not change because the bearings preload is the distance between the the inner race of the 2 bearings which is determined by the spacer ... that distance is not affected by the pinion depth. If it were a 742 you would set preload after you set the pinion depth. 741 has a spacer that I'm 99.9% sure pushes against the inner bearing race like the 489 crush sleeve.

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Lastly, does the pinion nut need to be torqued fully to take a pinion bearing preload measurement?



YES