Ring and Pinion gear teeth sheared root cause?

Hey all,

I am no gear expert but I am having an issue with my rear ring & pinion gears and would like some input from you all.

Background
I had a Detriot trutrac locker installed in March of 2018 by 4WP.

Situation
This past weekend I heard a loud bang while on trail and the truck had a rotational bang there on after until we got off trail. We knew it was in the diff and just thought the locker broke and was binding up.

However after towing it home and taking out the diff, the ring gear and pinion are sheared. As you can see, there is a bit of water mixed with the gear oil but not much and it couldn't have been in there too long. I don't do very many water crossings..

Questions
Could the water in the diff cause the breaking of the teeth?
Could it have been the incorrect setting of the backlash curing the locker install?
Is there anything else that could have caused it?

I would prefer not to be taken advantage of by 4WP. Thanks!

I would also like to add that I am not a "hardcore" wheeler or a rock-crawler. I am an adventurer so I am pretty mild on my truck.

 

These marks look like the pinion gear contacted the carrier. Did the pinion nut back off? Were the pinion bearings loose as a goose?

 

That is a good question! I am not exactly sure but I will look at that tomorrow! These are the pics that 4WP sent me so I haven't inspected it yet.

 

Good Lord, glad it didn't blow up with you on the high way man!

 

Did your truck start bucking when you lost traction off-roading? That could cause it, plus the water wasn’t helping. If not it could be installation error. 4WP isn’t where really good techs work that you want doing differential work.

 

You sure those are marks? They look like REFLECTIONS to me...

 

NO, I'm NOT sure. Just what it LOOKED like. Maybe they ARE reflections.

 

what was the driving situation that was occurring when it popped?

 

I think that's a reflection...I have had a pinion drive into the carrier in the front of a solid axle rig once. hit hard and the drive shaft bottomed out and forced the pinion into the 3rd. When i took the 3rd out it was obvious with the play in the pinon shaft (forward and back) and also the marks on the carrier. When that happened my gears were fine though.. Might have just been lucky...

It was also a open diff. With yours locked, it may have just bound real good when locked up and one wheel was caught and that was just the weakest of all the points to give...Maybe too much movement or space between the gear contact cause slippage or not proper meshing of the teeth on a load and in turn breakage so if they had to mess with that after the truetrac install, that would be where I would think my failure came from.

 

I was a bit off camber in the rear but all 4 tires had contact

 

Were you bouncing or the tires slipping?

 

That gear oil looks like shit for less than a year.
How many miles on it?
I would be leaning towards contamination if you found water in there.

 

4wp set up the bearings to tight on my 60 arb install causing the races to spin in the housing,
They refused all liability.
Ended up having a different shop fix it for around another $1000, I'm not gonna pay them to screw me twice.
To my knowledge they just higher dudes off the street and have no real diff experience.

I wouldn't pay them to fix it.

And I've never spent another dollar at that crap hole.

 

Yuuuup 4wp took 0 responsibility and wouldn’t really work with me on the price. Oh and they also didnt carry new 4.10 gears. Thus, I went with ECGS this next time around. Cheaper and 5 year warranty.

 

It happens with soft steel gear sets and where high traction is encountered

I've sheared many ring gears and snapped pinions but not in off road situations but drag racing . Something about launching off the transbrake at 4k rpm with hot / sticky slicks will do it everytime

Once I swapped to hardened steel Pro Gears I don't clean the teeth off the ring gear

 

4wp is a shit show sorry about that.
As far as water I'd say that is more of a rusty bearings then they spin out.
I'd say this is more of a fluke something came loose, or a shock load, or maybe just a bad set, hard to tell.

Do the diff breather mod.

And I know marlin has a strick 500 mile oil break in and change it or no warranty

 

That looks like spinning tires suddenly grabbing traction. In the first picture you can see where the teeth on the ring gear that are broken are bent. Although I am no expert.