Opened Chev. Tahoe differential and found this

[hcoles]

My 2006 Chev. Tahoe 2WD (125k miles) was making a bit of a swishing noise that seemed to be coming from the rear. I took it in to an independent shop specializing in rear end repairs for service and they found this and one axle end bearing that didn't look great but was serviceable.

What causes some rollers to be messed up and others to look not warn? It is amazing it didn't make more noise and breakup. Bearings are tough.

The diff. is a Gov Lock (Code G80). The guy said they break and I should replace with a limited slip at some point. I think the best replacement is a "gear" type diff. e.g. torsen truetrac.

They replaced all the bearings in the center area and installed new seals at the ends of both drive shafts. $560 later I was out the door.

[Arizona_928]

Any water in the diff?

[hcoles]

The guy didn't mention finding any water.

[asphaltgambler]

What you are seeing is 'brinneling' of the wearing surfaces. The hardened part of the rollers as well as the race has worn past and into the base metal. The result could be wrong type of oil, contaminates in the oil, or the oil has overheated to the point where it looses its lubricity properties and breaks down.

And / or overloading / over stressing those components. Lastly, improper installation where there was too much pre-loading on the bearings by not correctly shimming causing overheating under load. It can also be a combination of these factors

[onevoice]

Those rears have been around just about forever, and are usually pretty reliable. The gov-lock is also not a bad locking diferential, but will not take repeated abuse, especially with large off-road tires. If you are not in the habit of repeated burnouts, or heavy off-roading, it will probably last forever.

[Kraftwerk]

Ugh, "brinneling" that's what we all dread when we open up a hub or some bearing-thing. Never knew it had a name, never heard that word!
Tahoe is probably good for another 100,000 now.

[DanielDudley]

Could have run dry for just a short time. Once that type of wear starts, it just doesn't stop.

[hcoles]

Thanks for the comments.
What is a bit perplexing is rollers on the other side of the same bearing looked to have very little wear. Possibly a chunk of stuff went through that bearing and then fell down in the sump. I don't know. I'm glad to hear the gov-lock will last - of course the rear end place was saying they go out about at 125k miles with disastrous results. I was reading about the gov-lock and it seems it will not lock above a certain speed (20-25mph), that's comforting to know. I don't rely on the locking feature - I think it came on one time since I've owned it. I was crawling over some rocks up in the Sierras after ignoring a don't-go-here-without-4WD sign. I finally got turned around and back out of there.

[speeder]

My experience w owning GM trucks w the G80 locking diff is that it works great in snow/ice/gravel. If good AT type tires are installed, it's amazing what the truck will go through before 4wd has to be engaged.

Never had any maintenance issues w mine but also did not own for a long time.

[Kraftwerk]

My buddy has a Tahoe ... maybe '01? or '99?, I forget, but I think there is 235,000 mi. on it..

[asphaltgambler]

Originally Posted by Kraftwerk

Ugh, "brinneling" that's what we all dread when we open up a hub or some bearing-thing. Never knew it had a name, never heard that word!
Tahoe is probably good for another 100,000 now.

Kraftwerk - stick wit me! 😀

[Dansvan]

That is not brinelling. Most likely water contamination. Brinelling does not wear away the original surface.

[eastbay]

Flaking on rollers, search engine of choice is your friend. My opinion is poor manufacturing as opposed to wear or loading unless you you load it like a mule, damage looks like the poorly made offshore 996 IMSBs that pop.

next time try this
https://sfbay.craigslist.org/eby/pts/6022841425.html