Got new pinion, carrier, and wheel bearings installed at a reputable shop here in Detroit. Its all they do. I also had them add an Eaton Truetrac to it since my 01 XJ is 2wd. at about 60mph give or take 3mph there is a bit of a howl. Took it to them and drove the tech around and he said its perfectly normal. They did not do a new ring and pinion because they inspected it and said it was good. Just the bearings and Truetrac. Should I be concerned?

 

take it to another diff specialist and have them take a drive, a pro will pick up a bearing noise straight away

 

Sounds reasonable. Thanks.

 

If in fact they installed a used gear set you are likely SOL and stuck with what you got.

 

they just left the ring and pinion as is. i told them to replace it if it looked bad. they said "no".

 

So they just swapped the carrier then, leaving the ring and pinion as it was, shims and all? Thats not how you do it.

 

The way I am reading the OPs original post, the pinion bearings and carrier bearings were changed. If they did it right, they should have taken measurements before the work. Then after doing all the changes, they should have adjusted the shims to get the same measurements again (same contact pattern as before the work - or close to it). It is very possible that even if they did everything right, the contact pattern changed a little bit (but still within the allowable) and that change is causing the howl. I had my pinion seal changed in the rear, and when I got it back it was much more louder than before. It has quieted down some and now I don't notice it.

So when you hear the sound, are you pressing the accelerator or not?

 

you make a good point, but what rear diff does the OP have..presumably an 8.25, NOT a crush sleeve D35

also, if one reads up on Truetrac, some people love them, and reckon they are noiseless, but others dont agree

that is why, if easily practical, the vehicle should be test driven by a non-biased experienced diff specialist

 

The Chrysler 8.25 uses a crush sleeve also.

 

now that I think about it. it is slowly beginning to get quieter bit by bit. maybe after the bearing and shim refresh the gears need to learn to jive a little bit. also, the truetrac is amazing. i did a brutal and snowy winter (18/19) in michigan and it performed like a champ. i specifically took it out when it would dump a foot of snow just to see if i would have any issues. only fun. i had three bags of gravel in the rear though. 7/7 would do it again.