How do you break a axle?

How do you break an axle/drivetrain? Does it always happen when you’re stationary or almost so, pinned against an obstacle that you’re trying to mount and giving it more and more gas? Does it ever break on the go? Exactly what breaks, and how does it break? Is it always the weakest link in the chain that breaks, or does it depend on the circumstances? And what’s the hierarchy of exactly what the weakest link is (assuming parts in perfect condition), i.e., 260 u-joint breaks first if you have it, if you don’t have that then a D-35 will break before the 297 u-joints break, but 297’s will break before a D-44 will break, etc.?

Also, am I right in thinking you have to consider both the axles and the drivetrain? I hear things like if you get 35 inch tires you need a bigger axle, with no mention of the drivetrain, but it seems like the weakest link between the engine and the wheels is what will break.

often.

anything and everything will break eventually, it doesn't matter how "Heavy Duty" it is. Even non-technical terain will break axles and other stuff. You dont even have to be off roading to break stuff. If its on your truck it will beak.

The weakest link will always break.... that is, since it broke - it was obviously the weakest link. Predicting which one is weak link is difficult though - since not all parts are created equal. But if all the parts were created equal then you could predict that the weakest link would always break. Different cicumstances though make different things the weakest link. For instance, the d35 has weak axle tubes. On flat ground this isn't a problem, but with heavy tires and/or jumping it can become the problem. That sort of thing... I'll spare you my ignorance and leave any more specifics to more knowledgable people.

Concerning the drivetrain - the higher the output torque of the engine the tougher the rest has to be. The lower the gearing the tougher the rest of the drivetrain has to be (past the gearing, that is). But since the output torque of the 4.0 is fairly consistent across all models - it's not usaully discussed along with tire size or other factors when being discussed on an XJ or Wrangler board.

I know that doesn't help much, but since I'm no expert I'll leave the numbers and all that jazz to others....

Very easy and do not ask me how I know because I will plead the 5th

I’m not real sure where you want to go with this conversation, but it seem to me that the only answer to your question is that it depends. A better question may be to ask about the specifics in instances where people broke stuff. Driving over rough terrain is a very dynamic situation causing drive train loads to go all over the place. If you have weak stuff it’s going to break more than if you have strung stuff.
The only axel I ever broke sounds like I was trying to snap it to hear tell of it. I was fartin' around in a dirt lot with my new big tires and locker but before the regear and I got it in my head that I needed to climb this three foot ledge left by the earth movers. It was to steep for my entry angel, so I came at it at about a 45 and turned the drivers side wheel straight into the edge, then I started feathering the clutch (before the regear). That 260 let go so easy I thought that I had left it home. The moral of this story; don't turn your wheels when you are asking ones wheel to lift your whole rig up a shear ledge??? Or, 260’s are to weak??? Or, don't wheel till you regear??? In this case I don't think that a geo axel in the back would have let go before that 260. I have since run some hairy trails and not had another incident. :angel:

Bronco said:

I’m not real sure where you want to go with this conversation, but it seem to me that the only answer to your question is that it depends. A better question may be to ask about the specifics in instances where people broke stuff...

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Yeah, I guess that's mainly what I'm after, a description of what you were doing when something broke, as well as a description of exactly what broke, and then maybe some generalizations from people who have been around a lot of broken stuff. I'm just trying to get a feel for the real life situations behind some of the advice I've been reading in the archives. I've read stuff like you need bigger axles in you go over xx-inch tires (usually 33, some say 35) but stock axles are fine for smaller; rock crawling is where you break axles and drivetrain parts, you don't need a D-60 if you're just mudding; the gas pedal is what breaks things, so if your driving style is more finesse then you don't need bombproof stuff.

Where this is all going is I'm thinking of 32-inch tires to do some light rock-crawling type stuff, and I'm thinking of regearing to 4.56 and keeping my current stock axles (8.25 in back), with the idea that the lower gears will give me good climbing power and also help protect the weaker axles. But before I spend the money to regear I wanted to rethink the axles, whether my stock axles will be good enough, so I don't spend $800 on gears and then wind up getting new axles next year. Various other people have asked that question, answers come both ways but it sounds like stock is probably good enough, at least with the 8.25, for that size tire. But, in my usual irritating way, I'm trying to understand the theory behind it all, and theory is best illustrated with real life stories that demonstrate how the theory works. I like advice all right that says just "do this" or "do that", it's a good starting point, but I've got this bad habit of wanting to know why and to hear lots of details.

So, tell me how you broke your axle everybody.

OK maybe i can help alittle. One thing is that yes deeper gearing can help keep you from breaking since you can crawl instead of hamering on it but with deeper gearing those shafts are seeing more tourqe than before so that can also break them. you real didn't say what TAD you were considering but they can have a huge effect on how easy it is to break. Open front and rear its tough to break but still posible. with a locker in the rear ( i belive you have the 35 c-clip) you chances of breaking goes up real quick. you may wheel it for years and never have a problem but it may break frist time out. a girl in my local club has a tj with the 35 c-clip and wheel the snot out of it for a year with 32s and had no problems then we added a lock right and still had no problems for anothe year then we put on 33 MTRs this spring and was running 8s and 9s with no breakage untl last month when we entered the VA rock crawling championship and on the second day on an easy ledge that she should have walked up she hit the gas and the tell tale pop of a shaft followed by me spending some time under the jeep..
Now for the front the biggest problem is being on the gas and the wheels turned and teh u-joint working lose and rotating the clip off. with 32s your at the point of breaking the rear. so a 44 or a 8.25 29 spline would be good and safe. the front up grade to the larger joints and either mod the shafts for full circlips of tack welled the caps in place and keep an eye on them. I wwhat i said the end all of this dicusion NO but its steps in the right direction

REDXJ4FUN said:

) I wwhat i said the end all of this dicusion NO but its steps in the right direction

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"Me fail English? That's unpossible!" - Ralph Wiggum

Low gears, big tires, hard on drive line and trany (a bit) high gears, and big tires, hard on axle parts. Pick what you want to break

RedXJ, yeah, I've got the c-clip 8.25, and on TADs I’m thinking of the ARB air lockers front and rear. I can kind of see how that makes breakage more likely, but exactly how? Is it just binding when you’re on a good traction surface (like rough rocks)? With ARBs, couldn’t I get over that by being aware of it and unlocking, rocking it a little and then re-locking when I get in a bad spot?

Here’s some excerpts from another thread I just found this morning – sounds like pretty much all the stories are about the gas pedal. I can’t promise I won’t do something stupid but usually I’m not the run and gun type, more like go easy, if that don’t work back and try a little harder, etc. I’m not competing, just trying to get places. I haven’t really heard a story yet where a 35 or c-clip 8.25 just broke without lots of provocation, except the last one below and there aren't any details there.

Still, I have to say from the comments here and on other threads, it sounds like the better way to go is to upgrade the axles before spending all that money on gears and lockers.

Below are the stories. I was especially interested in the one about gradual breakage from twisting the axle over time, any thoughts on that?

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I broke my D35 twice with open diff and stock gearing running 31" m/t's. I am not easy on the throttle. I have a D44 now and have a complete spare D30. I am upgrading to D60 rear and D44 front in my new project. When I broke the first time I was going up rollover hill and just reached the top when SNAP! busted spiders rolled all the way back down it wasn't fun but a tree stopped me from rolling. The second time axle shaft snapped.

I blew up my Dana 35 spider gears on the street! But then again I was being sort of stupid with the gas

Running 33s..... Grenaded my d30 spiders last weekend... and it was a swapped in HP d30. My own fault though, bumped the front up and landed it under load.....Just for reference, no rocks down here.... Soup & mud but no rocks and folks are blowing their d35s on 32s & 33s....

During some bearing maintenance, I noticed the grain in the axles seemed twisted some, didn´t really know if it was machining or torque. Well being a curious type, I marked a straght line down the length of my axles with a carbide metal marker and inked it with machinists ink. A year or so later, pulled an axle out, and bigger than you know what, there was a twist in the axle. I´m thinking many of the broken axles are a progressive thing. They stretch until they break.

I was running 32in bfg muds with open diffs and very light on the gas, and still broke. And do you know what that c stands for? That means that the only thing holding that tire and wheel on is that c clipand its in the spider gears. So if you break that axle shaft, your tire, wheel and what is left of the shaft with fall off the jeep.

I think throttle kills axles. If you're a crawler type, you'll be fine. I also think what makes stuff break is when you jump and land under load, even just slightly, just slight bouncing while the wheels are spinning. When landing, the tire will get tremendous grip because of the extra weight/pressure on it, and the engine and drivetrain will have rotational inertia that won't just stop in an instant. With a locker you'll be more likely to break because a) with open diffs the load is always split in half over the two driveshafts and b) if you're boncing and spinning tires with open diffs you are very likely to bounce on one side at the time, allowing the wheel on the other side to spin. With a locker you risk getting all the torque on one shaft, which is twice the usual.

I broke my D35 spider gears, but that was because I didn't bother to use lsd additive in the diff oil, thinking the clutches were all worn out anyway. But they weren't, tires chirped on pavement and the spider gears broke after a week. Clever!

I blew up my Dana 35 spider gears on the street. That was because of copious ammounts of the go petal and leaving a stop sign I dont see why the axle broke with it being open and 32's (or may be it was because of the go fast goodies under the hood), factory equipment should be more heavy duty than that.

I have not had a problem off road with axle breakage but thats partially because I drive like Mrs. Daisy. It sucks enough doing axle work in the driveway, much less out on a muddy trail so why hit the stupid petal if you can finess your way through?

AARON

I agree with someone earlier in the thread who said "it depends"
My advice to you would to be to get out on the trails and see how it goes. Take it easy and take some junkyard spares with you. Learn how to swap an axleshaft if you don't know. While the official Jeep Jamborees cost money, they're a great way to get experience with trail leaders who are trying to get you through stuff without breaking. This is in contrast to some guys I know. (A well worn saying in our club is Don't Follow Ray)
Most local clubs will be happy to have a newbe in a stocker along on at least some of their trail rides. Most guys remember that they were once in your shoes. If they won't let you drive, ride along. See what other guys with a driving style similar to yours break. Find out what's on their wish list.
Good luck, get out there, enjoy what you have
mattk
('97, D44 front, CTMs, D60 rear, 35 splines, Detroits, 33s, soon AtlasII. Broke a u-joint once and a transfer case)