Dana 60 HP Gear failure, what happened?

['84 Bronco II]

Strange gear failure, what do you guys think went wrong? The gears only made noise above 40-50MPH (in a buggy) and have been like that for a while. It looks like some debris went through the gears, but I am not sure how since nothing else in the diff broke

 

['84 Bronco II]

 

[SLOWPOKE693]

Chipped a tooth and it spiraled downhill from there?

 

[total newb]

Yup. Odd are that centerd chip bust loose then proceded to wad the rest.

Make sure you clean out the cavity between the pinion bearings really weel. Thats where every thing ends up

 

[ScottRS]

HP rear? It looks like the gears spread some and walked the pinion high on the ring (lots of backlash direction) and when they were out to edge of tooth, it couldn't take it and let go.
Some guys will tweak setup for HP rears to run bare-minimum backlash and heavy carrier bearing preload to try and deal-with/prevent that.
The oddity to me is that the pinion breakage looks like it was spinning rear-axle direction when it broke, but a couple of the ring teeth look like it was spinning front-axle direction. Total Newb may have called it there, knocked off a chunk and proceeded to digest that chunk through the rest.

 

['84 Bronco II]

HP rear? It looks like the gears spread some and walked the pinion high on the ring (lots of backlash direction) and when they were out to edge of tooth, it couldn't take it and let go.
Some guys will tweak setup for HP rears to run bare-minimum backlash and heavy carrier bearing preload to try and deal-with/prevent that.
The oddity to me is that the pinion breakage looks like it was spinning rear-axle direction when it broke, but a couple of the ring teeth look like it was spinning front-axle direction. Total Newb may have called it there, knocked off a chunk and proceeded to digest that chunk through the rest.

HP front, but could have happened while backing up since he didn't know the gears were broken until he opened it up. It was making noise at speed and he though it was a bearing. Backlash was in the low end of the spec.

I think this should be chalked up to "shit happens" rather than anything in particular. It was just a really weird break I thought since I would expect entire teeth to break rather than just pieces and still be drivable.

 

[ScottRS]

I think this should be chalked up to "shit happens" rather than anything in particular. It was just a really weird break I thought since I would expect entire teeth to break rather than just pieces and still be drivable.

I've seen a lot of busted ring-n-pinions still driveable just making crunchy noises, driven home or at least back to camp on a few over the years myself. Dragged a guy back to camp from Backdoor years back on a busted one that would lock up about every hundred yards or so, his take was "go faster, let's see if we can shear what's left, off". Usually they'll hold at low (just street moseying level) power enough to drive, get on it a bit more and they start to skip or lock. Lucky in this case that it's in the "not that bad" realm, often when they're bad enough to be truly undriveable you also get wasted locker and/or busted carrier caps.