dana 30 ring gear fail

2000 XJ, stock 4.0, stock AW4, 231. 2" lift on 32" tires. 8.25 rear with OX locker, dana 30 in front with Trutrac, both regeared to 4.56 with Motive gears by me. It was my first time doing gear setup, but I'm a person who already had reason to own nice dial indicators and know how to use them and I was pretty confident I got everything right.

If anything went wrong, at the time, I thought maybe I overtorqued the front pinion pinion gear nut. The torque to turn it was in spec, but it took ridiculous effort to get there. I have a whole series of pics from the setup marked not good, meh, closer, getting better, almost there... I'm not certain this was the final pattern, but I thought I was getting close with this.

https://photos.google.com/photo/AF1QipOuPI-rbttVmxD7uL14qldwiPBQ9XERzWSewaHS

The diff ran warm (not hot) during breakin, but eventually seemed ok and I changed the gear oil after ~1000 miles. I just ran cheap 80w/90 gear oil. I run 4wd under light loads at highway speeds with studded tires on snow routinely. I wheel offroad fairly moderately, but a lot.

Fast forward 3 years and 30,000 miles... everything works great. Last weekend I was attempting a recovery of another vehicle with my jeep on level ground on dirt with good traction and my dyneema winch line down a 30 degree slope. The M8000 Winch wouldn't move it. I should have rigged a reduction system with snatch blocks but decided to try to pull with the jeep in reverse. I Put it in 4-low and couldn't budge it at full throttle. Then I made the dumb decision to try a little momentum. The winch line was pulling down on the front bumper, creating exceptional traction for the front wheels. The trutrac should be locked up in these conditions. I hit the throttle and got a loud popping grinding noise from the front axle on impact. Then I repositioned and did it again. Eventually the recovery worked out. Driving home, though... as soon as I hit pavement there was a grinding noise from the front axle. Putting it in 4wd made the noise go away when accelerating or braking. The noise was constant in 2wd and after removing the front drive shaft.

Today I pulled the diff cover, expecting to find shrapnel. Instead I found two spots on the ring gear more akin to what I'd call galling. Or would you call this chipped teeth?
https://photos.google.com/photo/AF1QipMfzHSEJw1fgj3Wno_fCLewAxZhCmPw3FbmAPwQ

https://photos.google.com/photo/AF1QipOS7-5fj5gZJ8yFMBRYwmXQf2URlUVE4B3am8Ez

So, my question for people who have seen other damaged ring gears.... Is there any indication in those pictures of lubrication failure, or bad gear setup setup? Or is this consistent with my poor decision to try a dynamic recovery with a static rope under a high traction scenario?

This is exactly the scenario I had in mind when I made the decision to put a bunch of lipstick (trackbar mount, gussets, control arm skids etc) on my low pinion dana 30. It should be stronger pulling in reverse than a high pinion axle.

Finally, should I...

• throw another cheap gear set in myself and get on with life but never make this same mistake again?

• 
  buy higher quality ring and pinion set? Higher quality gear oil?

• 
  take the opportunity to upgrade to a high pinion dana 30 (which wouldn't have prevented this particular scenario)?

• 
  Spend $4k on a bolt in aftermarket Dana 44 (kinda looking for an excuse to do that, honestly)... but would rather spend the money on new tires, brakes, PSC steering box, and more wheeling trips.

I don't intend to ever run tires bigger than 33"

The recover method seems to have been the deciding factor. WOT with a D30 is a bad combo

That said, I haven't had any luck with 4.56 with a Dana LP setup. There appears to be too much distortion under stress and I've torn teeth off the ring - 2 sets. My solution was to sell the rig as I was sick of fixing the same rig over and over

Upgrading to a HP30 may resolve your immediate problem though upgrading to a D44 would eliminate the housing issue entirely.

Sounds like "Mission Accomplished !!!" to me. Diff gears being the part that broke; must have built that turdy up right. Take it in stride, learn from the experience and carry on. Motive gears are straight off the boat; can't be sure what you're going to get and it's not that much more for a better brand (still might be "straight off the boat"). You have the tools, and now the experience, 2nd time around should be cake. Biggest single contributor to your issue was the lead foot and subsequent reduced blood flow to the cranium.

My vote would be option "A": throw another cheap gear set in myself and get on with life but never make this same mistake again?

But "D" is very tempting and the sort of decision I am prone to making. I did just pass up a Waggy front D44 for $200. Mostly because I don't want to have to change lug patterns, even though the axles I have in my rear D44 are probably already double drilld and would allow me to run 5 on 5 wheels. Still, like you, I don't have any plans to go to large enough tires to justify that much axle.

As others have said, I would be inclined to believe that the recovery method was the problem rather than the gear setup. Having 30K trouble free miles on your setup suggests it wasn't the problem.

One other item to consider for the future would be a dynamic recovery line. If you haven't seen Matt's Towing on Youtube you might want to look a few of his videos. In fact, there are a couple of videos with him and another guy comparing different dynamic lines: https://m.youtube.com/watch?v=kpqF9oVom2M Note that he is also running a low pinion front and often does recoveries in reverse. He seems to get away with it. Just some food for thought.

Your pics are not working.

Does this work... My chipped teeth

https://photos.app.goo.gl/DX2NUQ6hzYTL92s3A

That's not a "chipped" tooth, that's failure of the metal most likely due to either "poor" gears or improper break-in.

That is an interesting situation.

Particularly in that it occurred suddenly, under strain and in very limited locations.

"Spalling" might be the right term for it.

A quick search brings up an article from AxleTech on the subject of failure analysis. I would link to it, but the toy computer I am using doesn't seem to gracefully link a PDF. Service Manual AMT - 0445 with a date of September 2018 might be useful terms to help you find the article. Its focus is heavy trucks, but the principles probably cross over to your situation.

I'd put whatever gears you want back into it, buy more recovery equipment, and learn from this. Don't use your winch like a tow strap or recovery rope. It's not either of those. What would you be asking if your winch line snapped and came flying through the window at you? How to replace your face instead of your ring gear? I don't think the size of your tire, or the brand of gear you chose had anything to do with the gear breaking. I think it was a bad decision to yank on a winch and find the weakest part of the link you made.

Maybe I haven't broken enough ring and pinions. I just don't see how gussets, or lower control arm skids make your ring and pinion any stronger. If you want to invest in anything other than gears buy a 9,500 pound winch for extra pulling power. Remember, vehicle weight * 1.5 is the minimum, not the maximum, pulling capacity you want. We have no idea what the conditions of your recovery were including the vehicle you're pulling out. If it was a 5,000 pound half ton truck buried to the axles it matters vs a Suzuki Samurai.