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Next, I put the ring gear on the locker assembly.  The left photo shows using a socket to press the differential into the gear.  I left it under pressure so I could tighten the ARP 12 point ring gear bolts to 60 ft/lbs.  I used Loctite 271 to keep them in place.  The right photo shows the use of the carrier bearing adapter for pressing the bearings onto the differential.

Putting the differential assembly in the case is not a big deal, but measuring for setting the pinion depth is.  The Richmond spec on the gear was 1.040.  The basic idea is to measure the depth of the bore in both the bearing cap and the center section.  The two will probably not be equal.  Mine measured 1.457 in the cap and 1.434 in the case.  The difference is .023.  Divide by 2 to get .0115, which I rounded to .012.  I used the .012 figure as a “correction factor”.  Add .012 to the case bore depth to get 1.446, which would be the true centerline of the bearing bore.  Knowing the offset of the cap mounting face from the bearing bore centerline, I could then measure from the cap bolt boss to the rear of the pinion with a depth mike, then add .012 to get the true distance from the carrier bearing centerline to the pinion.  Now, I could just stack some shims, put them on the pinion support and mount the pinion.  I measured the depth and then added or subtracted shims as necessary.  I ended up having to go borrow some.  The final measure was 1.028 from the cap bolt boss to the pinion.  Add .012 and you get 1.040, the exact spec.


With the heavy math out of the way, I set the backlash.  The spec called for .008.  The trick here is to move the ring gear into the pinion using the adjusters. Use the left adjuster (left as viewed from the pinion flange with the case in the normal orientation) to put the final squeeze on the bearings for preload since it tends to move the ring gear away from the pinion.  Randy’s documentation says “I set the carrier bearing preload as tight as I can with a ten or twelve inch long spanner wrench.”.  I made the spanners with twelve inch handles just for that reason.  After about 12 tries, I ended up with .008 backlash.  Patience was key here as a small turn of the adjusters made a big difference.  I then checked the pattern and it looked like it was supposed to according to the sketches from Randy’s.