Broken ring and pinion gears

TJim

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Hey guys,
Yesterday, I went to a mild off road trip with some challenges but nothing too extreme. Mostly rocky stuff, a few mud points.

That happened to the TJ of a friend:

His setup is 2.5L engine, 33x12.5 BF KM3, 4.88 gears, stock dana 35 and dana 30 axles.

He realised that something went wrong when we returned to the road. He heard a noise, then he called for help.

What do you think happened? My guess is that maybe the guy that installed the gears didn’t do it correctly? Maybe he left some unnecessary slack between the gears?

* I must mention that the new gears were not installed in the past few months. Also, this is not his first off road trip after the installation of the gears. He is wheeling quite often. Not extreme stuff though.
 
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Damn that's not good! Surely they have a warranty if a shop installed them.
Do you think this is the fault of the guy that installed them?
I think that if something should break first with 33s and stock axles would be the axle shafts, since they are stock. Am I wrong?
 
Do you think this is the fault of the guy that installed them?
I think that if something should break first with 33s and stock axles would be the axle shafts, since they are stock. Am I wrong?
Breaking an axle shaft is not uncommon with a Dana 35 but certainly something was wrong with either the gears themselves or the guy totally botched the installation. That kind of R&P breakage makes me think more gear problem than install problem.
 
Breaking an axle shaft is not uncommon with a Dana 35 but certainly something was wrong with either the gears themselves or the guy totally botched the installation. That kind of R&P breakage makes me think more gear problem than install problem.
I just spoke with the friend.

The mechanic claimed that 33s put stress on the gears. He also claimed that if he had 4.88 with Dana 44 the gears would be stronger than 4.88 with Dana 35.

What do you think about those statements? I believe that he is just trying to scam him.
 
I just spoke with the friend.

The mechanic claimed that 33s put stress on the gears. He also claimed that if he had 4.88 with Dana 44 the gears would be stronger than 4.88 with Dana 35.

What do you think about those statements? I believe that he is just trying to scam him.
He's full of bullshit. 4.88 gears are VERY commonly installed into a Dana 35 with 33's.
 
That's the wrong question. The correct question would be do 4.88 gears have problems in the Dana 35 with 33" tires. The answer is a resounding no.
I understand that. Thats what I told him. Plus that stock axle shafts would be the first failure point in that case and not the gears.

I am just curious if there is any difference in strength between same ratio gears of dana 35 vs dana 44. Besides that case
 
Yes, the gears are bigger in a Dana 44 but that's not to say the 4.88 gears in a Dana 35 are not strong enough. They are for 33's.
Ok! Good to know! Thanks Jerry.

* offtopic: What about 35s? Would dana 35s with 30 spline axle shafts have a problem as far as gears are concerned?
 
That's the wrong question. The correct question would be do 4.88 gears have problems in the Dana 35 with 33" tires. The answer is a resounding no.
Do i understand it wrong that with Dana 35 and 33s the first thing to fail (if it fails, which can never happen) would be the axle shafts (assuming stock shafts, not any aftermarket chromoly) with bigger tires? Also, my understanding is that Spider gears is also a weak spot of stock Dana 35 diff, and they can also fail. It sounds really suspicious that Ring&Pinion in Dana 35 fails BEFORE the shafts or spider gears.
Also, with 2.5L engine and assuming 2.73 low gear - how is that even possible to create so much stress on ring and pinion to snap it like that?

Is that possible that whoever did the gear install did a very sloppy job and tries to get himself out of the heat but blaming anything but the quality of his job?
 
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The owner of that shop should come on here to defend his position on the gears not being strong enough. We'll tear him a new asshole.
He is Greek. Funny thing is that he is one of the “big” shops in Greece. However, they tend to bullshit everyone just in case they dont have the knowledge (most of them dont). I dont know if the same happens over there.

You cannot even imagine how many times I listen things that are opposite of what I learn in this forum. It is not even difficult for me to figure out who is right and who is wrong.

I am lucky that I found this forum and dont just spend money to build my TJ the wrong way.
 
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Do i understand it wrong that with Dana 35 and 33s the first thing to fail (if it fails, which can never happen) would be the axle shafts (assuming stock shafts, not any aftermarket chromoly) with bigger tires? Also, my understanding is that Spider gears is also a weak spot of stock Dana 35 diff, and they can also fail. It sounds really suspicious that Ring&Pinion in Dana 35 fails BEFORE the shafts or spider gears.
Also, with 2.5L engine and assuming 2.73 low gear - how is that even possible to create so much stress on ring and pinion to snap it like that?

Is that possible that whoever did the gear install did a very sloppy job and tries to get himself out of the heat but blaming anything but the quality of his job?
The usual point of failure with the Dana 35 is its axle shafts, not its gears. No telling if those broken gears are from shitty quality gears or a shitty installation but I'd lean toward a gear problem.