8 3/4 adjustments

[Blair Harris]

Just looking for some advice on setting up an 8 3/4 rear end. I am replaceing the axle bearings and inner-outer seals in the housing. I also took the pot apart and exchange the spider gears with a posi unit. It is a 741 carrier 391gear had to change the yoke also to accomidate the 10 spline 7290 big joint. I have not set up a rear end for 25 years and cant remember how to shim the pinion and set ther axle adjustment on the passanger side.
Any help would be appreciated.

 

[Supershafts]

To late now, those adjustments needed to be noted BEFORE you took it apart.

The pinion needed to be checked for preload prior and then reset, the BL needed to be checked and noted.
Now you need years of experience to know what you're going to do, or guess at where the original person set up the tolerances and then guess how much wear they got and add to that, so you're going to be removing the diff more than once to get it right.

The set up specs are different then what you need, was that diff set up at 6 bl or 8 bl or 10 bl and how much wear can you figure it has, can you read the pattern at all on the gears now.
The pre load will be re-set at a used bearing spec of right at 16 to 22 inch pounds.
You'll need a torque meter and dial indicator to set those

 

[crackedback]

You might get lucky on the preload. There is no crush sleeve on a 741, so you lucked out a bit there.

 

[fishy68]

Yep 741 and 742's have a solid pinion spacer so you lucked out there. Still wouldn't hurt to check it though to make sure it has a little preload (6-8 inch lbs.). With that said, the only adjustment is the back lash. As noted you should have checked it before dis-assembly but since you didn't all you can do is set it at .008-.010" and hope for the best.

To set the axle adjustment back off the axle adjuster and install the axles. Tighten the adjuster until all side to side axle play is removed. Set up a dial indicator on the drivers side and zero it out. Back off the adjuster one notch at a time until you get .008~.010" play. Install the locking tab and your done.