Odd thing happened. Did the ball joints recently due to terrible death wobble and fixed that. When pulling the axles noticed some scoring, then noticed I could wiggle my driveshaft from side to side (not good). Tore apart the differential and almost all bearings were shot. I always change my fluid regularly but was quite thick. I have no idea how nothing as leaking or there were no metal shavings - I could literally wiggle the carrier and pinion when I pulled it.

I though maybe the nut backed off but it was tight. Almost done the rebuild and gear pattern looks good. A few years ago had the carrier out and noticed barely any pre-load - literally just fell out. Not sure if this caught up but came like that from the factory.

Fixed the axles and yoke shafts with some speedy sleeves and all is good now. But still am curious as to the cause. I had tons of mud in the axles tubes - maybe some made it in. Or could the death wobble have contributed to this - I probably should have fixed it sooner than I did. I also took a few hits to the differential many times while on the trails.

 

How's your pinon angle? What type shaft are you running? It was likely a bad setup, otherwise excessive vibration form the DS due to really bad pinon angle may have assisted.

 

Stock shaft 3 inch lift. Angle seemed okay and shaft is fine - I would expect to see some wear on the shaft.. Going to add a set of control arm drop brackets, new driveshaft in the future.

Odd though, been driving like this for years and never had an issue. Even had the axles out a while back and everything looked good. I am thinking a combination the angle and excessive vibration from the death wobble - it was bad.

Still surprised the gears were in one piece. Will post a write-up on the rebuild.

 

I suspect you had bad bearings from the start

 

Check out the u-joint on the front drive shaft
Mine must have been going out for several months before it dried out in a bout of hot weather, and started to give vibration when going over 60.
Took it off and found it was seized only moving in one direction.
No signs in daily driving, but with hind sight months earlier heard some occasional slight squeaking when in low range.
However the extra strain on the front pinion bearings had taken its toll.
The u-joint is tack welded in so not user repairable, but fortunately there was a Drive shaft specialist not far away who had the equipment to remove it and tack weld in a new joint, re greased the CV joint and re balanced the shaft quite cheaply and saved the expense of a new one.
Find someone with a few grey hairs & knows what they are doing to replace the pinon bearings !
Must have been all those water crossings I've done getting through the perished rubber on the joint over the years.

 

Did you adjust the gear lube level after the pinion angle changed with the lift? Any increase of pinion angle should see an increase in fluid level to keep the pinion bearings lubed. Splash does some of it but an increased level is required. On Dynatrac HP 60 housings with over 12* of pinion angle they recommend a dual sump system to keep the pinion bearings oiled. In non-Dynatrac 60 housings we'll usually pack the pinion bearings with grease and overfill to assure a lubed start up. I've seen lots of damaged pinions bearings due to oil starvation- one to point of seizing after about 200 yards.