91 Rear Pinion rotational play (backlash?) (1 Viewer)

[Mixelplix]

I've recently been attending to some deferred maintenance on my 91 FJ80.

Eleven years ago I did axle rebuilds, and swapped to 4.88s. I did the work myself.

During a diff fluid change I noticed that my rear diff showed some gear wear. There were fine metallic particles on the magnetic drain plug. Not so much to be alarming (considering 11 years between fluid changes), but more than the front, which showed none.

While changing out my U joints, I noticed that my rear pinion nut was never peened down, and the pinion has a great deal of rotational play. I tightened the nut with an impact, and peened it down. The play was less, but still much more than I would expect.

Following the replacement of the u joints, I realized that some of the driveline slop I attributed to the u joints was actually the rear diff backlash.

How would I go about repairing this properly? Is it as simple as starting with torquing the pinion nut properly, and checking preload? Or should I remove the pinion flange, and replace the crush sleeve? Or is it potentially bearing replacement?

I'm just looking for some advice from someone more experienced, so I can order the parts and have them ready for when I toss it on the lift and roll up my sleeves.

 

[Shipwreck]

If you have excessive backlash, you should pull the third member and reset the ring gear and pinion. Backlash is primarily set by adjusting the side bearings in the carrier. It is measured at the ring gear once the final pinion depth is achieved. Torquing down the pinion nut will just increase the bearing preload. It also runs the risk of compressing the crush sleeve further, which will throw off the pinion depth. Best to order a new install kit and start over. It's up to you whether you want to reuse your old gears or order new as well. Interpreting a good pattern on worn gears can be challenging.