FZJ80 9.5" locking diff backlash tech

[bjowett]

Hello folks! Some possibly useful info for future gear swappers? While performing a 4.88 gear swap on the factory locking rear diff, my buddy and I could not get the backlash in spec, Precision Gear wants .008, the best we got is .016. Why is this? Normally, one would simply move the large adjusting nuts on a Toyota diff a smidge to tighen it up. Weeeeeeellllll, Toyota decided the locking diff would get shims! My bad assumption, should have lookined at the FSM. In my experience when dealing with diffs requiring shims, the old shims placed in their respective positions about and around the assembly with the new QAULITY R&P have brought things back to where they should be... usually.

I did not expect this to be a stocked item at my dealer, the closest set was out in California at the main warehouse. More down time, no biggy.

Questions, for those of you that have set up this diff, have you needed to change shims? For those that have not yet done this (but will), might be a good thing to get some of these before you rip in there...just in case!

 

[landtank]

I talked to the mechanic who did my gear swap and he mentioned the rear was a PITA! It took him several tries to get it dialed in.

 

[robbie]

In setting up the rear diff you may have to do it several time. We are out of a few shims but have a good selection of them in stock. If you used the old pinion shim you may not have the proper pinion depth. If I remember right the shim ends up being around .045-.050, you will be lucky if the shim you have is the right one. So it does take a lot of playing around and having a selection of shims in stock. John Hocker at Serria Vista usually has them in stock also. I do not know about dan the man. I usually set them at .007- .008 back lash and have always gotten a real good pattern with the percesion gear. The Factory gears are the easest to set up, but cost alot more. later Robbie

 

[bjowett]

My buddy set the pinion while I was away, so I am not sure if he used a thicker shim there.... I had every shim under the sun for setting pinion depth and preload. The pattern is perfect right now, it just needs that smidge of slop taken from the backlash. Thanks for the input!