392 broken axle

[rdfact]

I have a ‘21 JLUR-XR. My front axle just has plug welds. I can only see one, I assume/hope there is another behind a bracket. No welds around the perimeter of the tubes in that area.
So these are just press fit with a couple plug welds? Would some welds around the perimeter of the tubes have helped in this situation?

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[chevymitchell]

I have a ‘21 JLUR-XR. My front axle just has plug welds. I can only see one, I assume/hope there is another behind a bracket. No welds around the perimeter of the tubes in that area.
So these are just press fit with a couple plug welds? Would some welds around the perimeter of the tubes have helped in this situation?

There should be 4 welds, I believe. I have welded many tubes to housings to help with strength. It wouldn’t have helped here though. The tube would have bent even if the cast housing didn’t break. Best thing for this is a truss. Even then, you’ll end up bending the C or bending a ball joint or cracking the knuckle. Something is going to give. Bottoming out your bump stop hard like this will destroy all sorts of stuff.

 

[Paluss]

You can get an empty housing for $1k. So, that plus the labor to swap all parts over. $3k is a good number for this.

Thanks!

 

[chevymitchell]

Thanks!

This person needs to make sure they inspect everything.

The spring perches are likely bent, too, which could be hiding cracked welds on the frame.

Think about the energy transference in a logical sense and in straight lines. Follow the energy and inspect everything.

In order for the axle to break like this, there has been an enormous amount of leverage. That $3k could be $5k+ easy depending on what happened to the rest of the energy.

 

[Canjeeper]

Increasing the thickness will not help with what happened here.

Even if you had something like a ProRock 44 without the FAD, the tube would still bend. 60’s will bend. If you out-drive your bump stop on one side of the rig, then this is the price you pay, especially if you repeatedly do it. Your best bet is to hit the wash out at the same time with both tires so you can double the up-travel resistance.

The factory axles aren’t built for this style of abuse. Even the XR with the thicker tubes aren’t made for it. Gotta upgrade everything around the axle and even then, bottoming out the bump will break all sorts of things.

The Rubicon tubes are the same thickness as the other axles. The only tube that’s thicker is the XR axles.

Like i said, what kind of abuse ? we have no idea . If a Jeep part breaks is it obvious driver error ? I have seen lots of abused Dana 44 solid axles in full sized 3/4 ton trucks with big block engines hold up fine with 1/2 inch thick axel tubes . They all have bump stops .

 

[chevymitchell]

Like i said, what kind of abuse ? we have no idea . If a Jeep part breaks is it obvious driver error ? I have seen lots of abused Dana 44 solid axles in full sized 3/4 ton trucks with big block engines hold up fine with 1/2 inch thick axel tubes . They all have bump stops .

The kind that bottoms out the bump stop… I’m not sure I can make it any clearer. Lol. Size of the engine doesn’t matter. It’s an up travel issue. With these 392’s and XR’s, you have about 2-2.5” before you smash the bump stop.

By abuse, I mean, driving your rig outside its means. You can use abuse and ignorance laterally here. Almost no one pays attention to the actual geometry of their rig. Bolt on some cool stuff and go play.

 

[Canjeeper]

The kind that bottoms out the bump stop… I’m not sure I can make it any clearer. Lol. Size of the engine doesn’t matter. It’s an up travel issue. With these 392’s and XR’s, you have about 2-2.5” before you smash the bump stop.

By abuse, I mean, driving your rig outside its means. You can use abuse and ignorance laterally here. Almost no one pays attention to the actual geometry of their rig. Bolt on some cool stuff and go play.

So your advice is dont bottom out your bump stops if you own a Jeep ? Weight does matter Bigger is usually heavier .

 

[chevymitchell]

So your advice is dont bottom out your bump stops if you own a Jeep ? Weight does matter Bigger is usually heavier .

What are you missing here?

My advice is don’t out-drive your equipment. I don’t care if it’s a Jeep, TRX, PowerWagon or something you built yourself. The geometry doesn’t lie. If you fail to calculate your limits or simply not pay attention, stuff like this axle breaking happens.

Weight certainly matters. More weight means more spring rate needed. More weight means more lb per inch of shock load needed. Means more bump space required. It’s not just weight over the spring either. It’s unsprung weight.

Washouts will appear out of nowhere. Driver error isn’t always intentional.

 

[donmontalvo]

You can get an empty housing for $1k. So, that plus the labor to swap all parts over. $3k is a good number for this.

Seems like you'd be able to get a complete front axle for $3K.

I was able to get front/rear takeoffs from a 2020 Rubicon for my previous Sport S for just under $3500.

https://donmontalvo.com/2020/11/29/more-pre-moabrubicon-mods/

 

[chevymitchell]

Seems like you'd be able to get a complete front axle for $3K.

I was able to get front/rear takeoffs from a 2020 Rubicon for my previous Sport S for just under $3500.

https://donmontalvo.com/2020/11/29/more-pre-moabrubicon-mods/

That’s honestly the way I would go, as well. It’s really the best bang for buck. No better excuse to get a PR44 though. Lol. 392 doesn’t use the FAD, anyway.

 

[Canjeeper]

What are you missing here?

My advice is don’t out-drive your equipment. I don’t care if it’s a Jeep, TRX, PowerWagon or something you built yourself. The geometry doesn’t lie. If you fail to calculate your limits or simply not pay attention, stuff like this axle breaking happens.

Weight certainly matters. More weight means more spring rate needed. More weight means more lb per inch of shock load needed. Means more bump space required. It’s not just weight over the spring either. It’s unsprung weight.

Washouts will appear out of nowhere. Driver error isn’t always intentional.

My problem is that you stated this was a driver caused situation without knowledge of what the actual cause was . You sounded like a Service writer at a dealership .

 

[chevymitchell]

My problem is that you stated this was a driver caused situation without knowledge of what the actual cause was . You sounded like a Service writer at a dealership .

That’s what experience and years of tuning rigs gives you. Not sure how that compares to a service advisor, but it’s too obvious to me what happened. If you don’t understand it, that’s ok. That’s why there’s great people on this forum to help.

I can look at those pictures and tell what’s happened. It’s a common failure. You don’t bend an axle tube and have a catastrophic failure of the axle without an error. There is no amount of material degradation that would cause what you see in those pictures without some driver error/influence.

The 2nd most common failure like this is people that re-tube or truss housings and don’t weld things properly or control their heat. Then you end up with something like this:

There are many examples of this failure. A lot of them happen in sand. People like to blame the FAD. The truth is, it’s them out-driving their rigs. Almost always driving too fast and not enough up-travel available.

 

[chevymitchell]

There’s a reason Jeep has a trim called the Rubicon and not Baja. It’s an off the shelf rock crawler. The best you can get is the Mojave edition of the JT. Even then, it’s not a race truck. Play stupid games, win stupid prizes.

You can’t drive a mass produced machine like you want. There are limits. The TRX and Raptor are great examples. You can break those trucks doing the same thing. The ones that break are driven outside of their limitations nearly every time.

 

[Spartan99]

Forget the axle. Anyone notice the scratch on the frame from the winch install?!

 

[19 JLUR Bright Whit3]

Forget the axle. Anyone notice the scratch on the frame from the winch install?!

You cant forget the....

"Hey, you cant park there". LOL

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