392 broken axle

[supermike]

Not my vehicle, shared by my friend. Seems the breaking point is at the welded plug/pin and axle tube slide out afterwards. Rarely not actually snap in half or cracked at the FAD housing. At the end of the days it’s still a wrangler with even heavier front end applying more force…

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[2nd 392]

Not my vehicle, shared by my friend. Seems the breaking point is at the welded plug/pin and axle tube slide out afterwards. Rarely not actually snap in half or cracked at the FAD housing. At the end of the days it’s still a wrangler with even heavier front end applying more force…

Did it break on the road or was it towed there? Hopefully not on the road, would not be a good sign. Edit—upon further viewing I doubt if it could be pulled there.

 

[Babeinsap]

Almost looks like it was not fully welded around maybe just the plug weld?

 

[JLDIESEL]

Truss and guss!

 

[chevymitchell]

Not my vehicle, shared by my friend. Seems the breaking point is at the welded plug/pin and axle tube slide out afterwards. Rarely not actually snap in half or cracked at the FAD housing. At the end of the days it’s still a wrangler with even heavier front end applying more force…

This looks like the bump stop bottomed out during some spirited driving. If you continually hammer your bump stops, then the axle can't go up anymore. If the axle can't go up anymore, but all the weight of the Jeep is still trying to push the tire up, the bump stop will act as a fulcrum point. The the weakest point on the opposite side will break. I don't see anything here that looks like an oddity. The scenario I just mentioned can happen if you hit something big with only one side of the axle, like a wash out on the passenger side while driving at a speed too great for the spring, shock, and bump stop to do their job.

In other words - Fuck around, Find out. Lol

I'm certain this is what happened. See Banana picture below.

Tube is bent up from housing to FAD.

 

[Renegade]

We’ve seen a few axle tubes break at the FAD housing, but this one does seem to have broken the welds, and the tube slid out. A rotational or lateral shear force would be required to do that.

 

[chevymitchell]

We’ve seen a few axle tubes break at the FAD housing, but this one does seem to have broken the welds, and the tube slid out. A rotational or lateral shear force would be required to do that.

Yes, the scenario I spelled out in my previous post breaks these welds and literally pulls the tube out of the FAD.

The bent tube gives it away as to what happened. As the tire was shoved through the bump stop, it pulls everything down and out.

This is a common failure in any live axle setup. Main reason why Baja uses independent suspension up front. The inability for the two tires to move individually with what cause this.

There isn't a failure of the Jeep here. This is 100% driver error and driving past the mechanical limitations of the rig. Stock, these things aren't meant for this type of abuse.

If you look at the bottom of the FAD tube, it's broken out. The top weld, the one you have circled, just breaks off. The top of that weld is still intact, but the weight of the Jeep when it hit will break something that small very easily.

 

[chevymitchell]

We’ve seen a few axle tubes break at the FAD housing, but this one does seem to have broken the welds, and the tube slid out. A rotational or lateral shear force would be required to do that.

There was another post on here a while back... I think it was a Red Jeep in the sand dunes. Broke his axle, as well. Silly foam bump stops. Good for rock crawling, not forest road bombing. Lol.

 

[Canjeeper]

Without knowing what was hit, it is hard to speculate on the guilty partner .

 

[chevymitchell]

Without knowing what was hit, it is hard to speculate on the guilty partner .

This is a very common failure for live axles. Certainly driver error.

 

[Canjeeper]

Why did jeep increase tube thickness on Rubicons ?, maybe they need to increase it again for the heavier 392 ?

 

[chevymitchell]

Why did jeep increase tube thickness on Rubicons ?, maybe they need to increase it again for the heavier 392 ?

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.

 

[Ted392]

392's have very little bump stop gap. Plus, this one seems to have a wide stance with fender chop.

 

[Paluss]

I'm sure warranty won't cover the repair. Curious what will it cost to fix $3,000?

 

[chevymitchell]

I'm sure warranty won't cover the repair. Curious what will it cost to fix $3,000?

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.

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