JK Axle *TUBE* Failures?

[chuck45]

The bent C's and trackbar mounts breaking are the most common issues right now.
It's a good thing to watch though.

That's what I've been noticing too. The ORE gusset kit seems to take care of the C issue. Mt Logan also offers a weld on gusset but it seems to have less coverage than the ORE ones.

Trackbar mounts are a bit problematical. They seem ok if the JK is left stock but with any extention upward (to correct bump-stear issues) they are stressed and break unless braced. Rock Krawler makes a 20.00 two piece gusset kit that supposedly braces it and eliminates problems. I've bought it but haven't got around to installing it yet. JKS makes a real substantial kit that reinforces it, braces the passenger side upper control arm mount and provides the option of a high and low (std) track bar pivot position.

 

[R_Lefebvre]

As I posted in one of the threads, I wasn an engineer at Dana a few years ago. I was doing underhood plumbing not axles, but we had a problem with bad batches of steel tubing coming out of the mills. The macroscopic carbon concentration was ok, but you would have large microscopic pure carbon inclusions that were making what is supposed to be a ductile low-carbon steel actually be brittle. That's kinda what this looks like to me.

As for all the discussion of the way the axle flexes... what kind of suspension is it? 4 bar or 3 bar? 3 bars have no geometric problems, but 4 bars do have bind designed in. The 80's - 90's Mustangs had a 4 link called "Quadra Link" which we called Quadra Bind. It's what made those cars handle so bad. There's a geometric problem, which can only be compensated by large rubber bushings.

My Rover has no upper arms, just semi-rigid lower arms which definitely twist the housing when it articulates. I say semi-rigid, because the arms aren't welded to the housing, but mounted with large bushings.

 

[Zeero]

I know of two people in the JK's this has happened to, but they were not D44's, they were the D30's that broke on two separate occasions with different Jeeps....one was an X model, the other a Sahara.

 

[SixLug]

As I posted in one of the threads, I wasn an engineer at Dana a few years ago. I was doing underhood plumbing not axles, but we had a problem with bad batches of steel tubing coming out of the mills. The macroscopic carbon concentration was ok, but you would have large microscopic pure carbon inclusions that were making what is supposed to be a ductile low-carbon steel actually be brittle. That's kinda what this looks like to me.

As for all the discussion of the way the axle flexes... what kind of suspension is it? 4 bar or 3 bar? 3 bars have no geometric problems, but 4 bars do have bind designed in. The 80's - 90's Mustangs had a 4 link called "Quadra Link" which we called Quadra Bind. It's what made those cars handle so bad. There's a geometric problem, which can only be compensated by large rubber bushings.

My Rover has no upper arms, just semi-rigid lower arms which definitely twist the housing when it articulates. I say semi-rigid, because the arms aren't welded to the housing, but mounted with large bushings.

Thanks...thats what I was looking for. Bushings are the saving grace for those then. I was thinking more about a 4-link.

 

[Root Moose]

It's a materials problem that was supposedly corrected during the `07 model year run. Both Dana 44s and Dana 30s are affected. The failures happen on both street trucks and wheeling trucks.

One of the guys I know was on an EOTB run a few weeks ago and a JK had this happen to it. Sure enough, MY07.

 

[chuck45]

As I posted in one of the threads, I wasn an engineer at Dana a few years ago. I was doing underhood plumbing not axles, but we had a problem with bad batches of steel tubing coming out of the mills. The macroscopic carbon concentration was ok, but you would have large microscopic pure carbon inclusions that were making what is supposed to be a ductile low-carbon steel actually be brittle. That's kinda what this looks like to me.

As for all the discussion of the way the axle flexes... what kind of suspension is it? 4 bar or 3 bar? 3 bars have no geometric problems, but 4 bars do have bind designed in. The 80's - 90's Mustangs had a 4 link called "Quadra Link" which we called Quadra Bind. It's what made those cars handle so bad. There's a geometric problem, which can only be compensated by large rubber bushings.

My Rover has no upper arms, just semi-rigid lower arms which definitely twist the housing when it articulates. I say semi-rigid, because the arms aren't welded to the housing, but mounted with large bushings.

I think a lot of failures we see today are due to poor materials. I was recently on a job where we had a 40 ft piece of 7" pipe split at it's seem for 35 ft of it's length; at a fraction of it's rated burst pressure. Most pipe has a seem; you just can't see it (nobody wants to pay for seamless). The pipe had been sourced in China. The Asian pipe we're working with today is thought of as junk and doesn't hold up.

So I'm curious, do you know where the tubes in the axles that failed came from? Was it domestic or foreign? How does something like this slip past QC?

As to the issue of 3 and 4 link and bushings - how do arms that have johnny joints or superflex joints compare to bushings? From what I can see there is more articulation with the flex type joints. I know on my setup I have a bushing at one end of a control arm and a flex joint in the other. For instance the front uppers have a bushing at the axle and the lowers have the bushing at the frame.

 

[R_Lefebvre]

So I'm curious, do you know where the tubes in the axles that failed came from? Was it domestic or foreign? How does something like this slip past QC?

I don't know where the axles came from, but the tubing I had problems with came from the good ole' USofA. Anybody is capable of producing junk.

How does it get past Q&A? I can't speak with authority on axles, but *generally* in the auto industry... there is NONE. Well, at least not what you'd think. All the "torture testing" happens before a vehicle launch. After launch, there really isnt much materials testing going on. As long as the parts fit the jig after welding, they're good to go. The Tier 1 supplier relies on the steel supplier to self-certify the material. Fox watching the hen house.