So, my new-to-me 99 XJ that I've had a month or two now has been making a little noise in the rear, or so I thought, not really sure. Is making a little whining noise, only after it's warmed up, only on decel, not real loud, pitch changes with vehicle speed, not with engine speed or trans/gear related. I was thinking might be tires, so replaced all 4 tires and noise did not change. Is 2WD, auto trans, and has Chry 8.25 rear. I pulled the diff cover, nothing visually unusual in there, no chipped or broken teeth, no metal laying in the bottom of the diff, fluid poured right out, was thin and dirty, there was a light "brassy" looking sheen to it that floated to the top in my drain pan, but minimal. I cleaned it out real well and refilled with Amsoil Sever Gear 75w140 and....noise is still there. Possibly a little quieter but, still noticeable.
Oh, one other thing I noticed. When I had the back of the Jeep jacked up and the diff cover off, I spun one wheel lightly so I could see all the teeth and look things over. There was a little bit of resistance, then the wheel would move freely and kinda coast on it's own, then bind up and there was resistance again. Bearing hanging up? Something out of alignment? Normal? Source of my noise?
Your thoughts?

 

i would check the drum brake that might be rubbing either onto the brake shoe (perhaps need replacement ?) or the drum rubbing onto the backing plate of the brake assembly. noises from the rear are not easy to locate.

marc

something similar i had with my 88 xj when i put brandnew drums on they rubbed a bit on the backing plate it was rust build up i used a file to make it smooth again just a tiny bit and the rubbing was gone

edit: also by looking at the differential its hard to determine unless you really grab a hold on the carrier and try to jerk it a bit perhaps with a piece of wood underneath the carrier and push it up to see any play if the carrier bearings are worn. reachng from the front of the differential by holding the yoke and try to push that up and down to spot any play.

 

since you seem to have enough oil in there and mine pretty much ran dry i experienced this:

im not saying that this is your problem..

https://cimg9.ibsrv.net/gimg/www.che...c5ce8746b7.jpg

but you cant see this unless you take it apart.

edit: also a thing you could check is the parking brake cable that could be rusted up and not retracting well and keeping the shoe engaged what creates resistance of course

 

now dont mistake play for backlash (which is suppose to be there).. you are looking for play at the carrier bearings so you look for movement of the carrier not the ring gear.

 

i hope i explained it good, in the video you see the play (backlash) that you DO want