Loose preload on front diff pinion.

[zz_denis]

So my truck started making a VERY loud humming noise while decelerating in 4x4 all of the sudden. I disconnected the front drive shaft, and noticed that the companion flange on the front diff has a TON of in an out play. Probably 1/8-1/4". It was so bad that when its pushed in, I could spin it by hand without the pinion teeth even contacting the ring teeth!

The pinion nut was staked properly and did not back out. I tightened the nut further to 200 ft/lb to see if it would help. It removed some play, but its still significant. (just did it to help troubleshoot, i know i cant drive it without setting the preload properly).

Another weird thing is that when i disconnected the driveshaft flange, there was some gear oil BETWEEN the driveshaft and diff companion flanges! How is this even possible?!

What could have caused this? I will probably need to rebuild the diff, but im wondering if i can salvage the gears from it? It's the rare 4.56 gears and would be impossible to find used ones around here.

 

[broken wrench]

You need to open it up and check gears for damage. Crush sleeve failure is most likely culprit.

 

[zz_denis]

Why would the crush sleeve fail all of the sudden?
The truck didnt see anything other than city driving on paved roads for atleast a month prior to this problem happening.

 

[broken wrench]

As the name implies it is a crush sleeve, at some point it could have sustained a jolt and compressed it enough to make slack in your preload. Then over time the pinion moving crushed it further till it let go. But could also be bearing failure, your going to have to open it up to know for sure. Hopefully pinion only contacted carrier some and didnt chip ring or pinion. I have run chipped gears for fronts but never rears.

 

[nevada]

So my truck started making a VERY loud humming noise while decelerating in 4x4 all of the sudden. I disconnected the front drive shaft, and noticed that the companion flange on the front diff has a TON of in an out play. Probably 1/8-1/4". It was so bad that when its pushed in, I could spin it by hand without the pinion teeth even contacting the ring teeth!

The pinion nut was staked properly and did not back out. I tightened the nut further to 200 ft/lb to see if it would help. It removed some play, but its still significant. (just did it to help troubleshoot, i know i cant drive it without setting the preload properly).

Another weird thing is that when i disconnected the driveshaft flange, there was some gear oil BETWEEN the driveshaft and diff companion flanges! How is this even possible?!

What could have caused this? I will probably need to rebuild the diff, but im wondering if i can salvage the gears from it? It's the rare 4.56 gears and would be impossible to find used ones around here.

it leaks out the splines. pretty common. just need to put some sealer on the splines when it goes back together. not a big deal.