Aluminum knuckle failure

[AnnDee4444]

I hit a raised berm of dirt going about 25-30mph with the passenger side of the rig. Had to swerve off trail to avoid a speeding biker coming over the crest in the opposite direction. Big long straight graded dirt road with some desert shrubbery and uneven terrain to the side - the uneven terrain is what my passenger side went out into. The front passenger wheel took the majority of the force, and the axle was the only thing damaged other than the wheel pushing up enough to pop a couple fender clips. I was running 29lb wheels and 66lb 35 Patagonia MTs and other than a Steersmarts track bar, the rest of the front end components were stock at the time.

The axle bent a few degrees upwards on that side - it didn't totally break but instead the FAD housing cracked at the spot welds and the tube going from the FAD to the C was pushed upward now that it was loose from the FAD housing's spot welds. Result was some funky camber on that side but was drivable (carefully) home. This pic was from below looking up, you can see the cracked paint between the FAD and tube suggesting upward tube movement, and if you look lose on the spot weld in the top right you can see cracks surrounding it. The other spot weld was a bit worse but I can't find the other pics.

Interesting that the knuckle held up here... had it broken, it might have been a cheaper fix (but you wouldn't be driving home).

Out of curiosity, what offset are your wheels/spacers? Was the sway bar connected during impact? Stock shocks?

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[jessedacri]

Interesting that the knuckle held up here... had it broken, it might have been a cheaper fix (but you wouldn't be driving home).

Out of curiosity, what offset are your wheels/spacers? Was the sway bar connected during impact? Stock shocks?

0 offset wheels and no spacers, so they poke about 1.5" over stock. I stayed somewhat conservative with the offset as I was initially worried about the additional torque/leverage over the axle when the wheels are sent out much further than stock offset. Swaybar was connected as this was before I had my tazer for higher speed electronic disconnect, and the shocks are Fox 2.0s for 2.5" lift. The rig itself had a 2.5" Rock Krawler lift with only front lower adjustable control arms, rest of the control arms were stock at the time. I'm running no bump stops other than factory foam piece on the upper perch. That whole side bottomed out as hard as anything can possibly bottom out and sent me basically airborne in the cabin.

As for the knuckle, yeah - I think it shows that they're not always the weakest link. I'm still running the same knuckles that were involved in the incident, it's now the only original factory part on my front axle aside from brakes. I was out of town working when the new axle came in so instead of wrenching the new axle on myself, I had a shop do the swap. From that I've gained a bunch of hammer impact marks on the factory knuckles from when they likely couldn't get it off the balljoints easily to transfer to the new axle. I'm now seriously looking at going to steel, but I just spent $800 on full set of Metalcloak control arms a few days before this thread popped up on here, lol. As far as I can tell there's no wallowing of the balljoint or steering hardware mounting holes and no obvious damage other than the shop's hammering marks. Rig tracks great, has no death wobble and I'm not running a steering stabilizer.

 

[19 JLUR Bright Whit3]

0 offset wheels and no spacers, so they poke about 1.5" over stock. I stayed somewhat conservative with the offset as I was initially worried about the additional torque/leverage over the axle when the wheels are sent out much further than stock offset. Swaybar was connected as this was before I had my tazer for higher speed electronic disconnect, and the shocks are Fox 2.0s for 2.5" lift. The rig itself had a 2.5" Rock Krawler lift with only front lower adjustable control arms, rest of the control arms were stock at the time. I'm running no bump stops other than factory foam piece on the upper perch. That whole side bottomed out as hard as anything can possibly bottom out and sent me basically airborne in the cabin.

As for the knuckle, yeah - I think it shows that they're not always the weakest link. I'm still running the same knuckles that were involved in the incident, it's now the only original factory part on my front axle aside from brakes. I was out of town working when the new axle came in so instead of wrenching the new axle on myself, I had a shop do the swap. From that I've gained a bunch of hammer impact marks on the factory knuckles from when they likely couldn't get it off the balljoints easily to transfer to the new axle. I'm now seriously looking at going to steel, but I just spent $800 on full set of Metalcloak control arms a few days before this thread popped up on here, lol. As far as I can tell there's no wallowing of the balljoint or steering hardware mounting holes and no obvious damage other than the shop's hammering marks. Rig tracks great, has no death wobble and I'm not running a steering stabilizer.

I've been looking at the MetalCloak control arms. Where are they at $800? I'll install them while waiting for my RCVs. LOL

3:31 PM (5 hours ago)
to me

Thank you for your recent order. We don't currently have any of the RCV axles you ordered in stock right now. According to our supplier, we're looking at about 12-14 weeks to get your order shipped

If you're okay with the delay, there's no need to follow up, and we'll send you tracking as soon as possible.

Thanks, talk to you soon.
-Poly Performance

 

[jessedacri]

I've been looking at the MetalCloak control arms. Where are they at $800? I'll install them while waiting for my RCVs. LOL

Screaming Facebook Marketplace deal find. Guy had a full 3.5" GC kit installed by Rebel Offroad and decided 1000 miles later he wanted to go long arms and 60s so he sold the MC arms off. They are essentially brand new and look fresh out of the packaging, but the jam nuts were seated with an air hammer so it's going to be brutal getting them loose to set them for 2.5".

The MC stuff is IMO the best in the business for midarm JL suspension. Buddy of mine has been wheeling the absolute piss out of his JLR for nearly 4 years now and the MC bushings are still good. They flex so nicely and require no maintenance along the way.

 

[19 JLUR Bright Whit3]

Screaming Facebook Marketplace deal find. Guy had a full 3.5" GC kit installed by Rebel Offroad and decided 1000 miles later he wanted to go long arms and 60s so he sold the MC arms off. They are essentially brand new and look fresh out of the packaging, but the jam nuts were seated with an air hammer so it's going to be brutal getting them loose to set them for 2.5".

The MC stuff is IMO the best in the business for midarm JL suspension. Buddy of mine has been wheeling the absolute piss out of his JLR for nearly 4 years now and the MC bushings are still good. They flex so nicely and require no maintenance along the way.

That’s awesome!

 

[falcon241073]

https://www.ebay.com/sch/i.html?_fr..._TitleDesc=0&_odkw=jeep+trail+badge&_osacat=0

Damn $45-$50 a badge?? I have a bunch of the original style badges and when Jeep switched styles they sent me replacement badges for my old style badges. Hmmm…

 

[AnnDee4444]

the shocks are Fox 2.0s for 2.5" lift. The rig itself had a 2.5" Rock Krawler lift with only front lower adjustable control arms, rest of the control arms were stock at the time. I'm running no bump stops other than factory foam piece on the upper perch. That whole side bottomed out as hard as anything can possibly bottom out and sent me basically airborne in the cabin.

So the shock bottomed out before the bump stop? I could see how this might put high loads in the wrong areas... even possibly a twisting motion (shear).

From that I've gained a bunch of hammer impact marks on the factory knuckles from when they likely couldn't get it off the balljoints easily to transfer to the new axle.

Marks on the side? That's actually a method to separate the knuckle from the ball joint without a pickle fork (method #2 in this video). It saves the balljoint boot. Not sure if it's a good idea on aluminum though.

 

[jessedacri]

So the shock bottomed out before the bump stop? I could see how this might put high loads in the wrong areas... even possibly a twisting motion (shear).

Marks on the side? That's actually a method to separate the knuckle from the ball joint without a pickle fork (method #2 in this video). It saves the balljoint boot. Not sure if it's a good idea on aluminum though.

I'm not actually sure if the shock bottomed out first or not. The impact was wholly too much for the entire suspension / axle to compensate for no matter what I was running I think.

And yeah, they did bust off the knuckle with a hammer like that, but they didn't need to save the balljoints. My new axle came with Spicer HD ones pre-installed in the Cs. All I can think about is the aluminum structure inside not being too happy about all it's been through between the original impact and the aggressive remove/reinstall.

 

[gato]

I hit a raised berm of dirt going about 25-30mph with the passenger side of the rig. Had to swerve off trail to avoid a speeding biker coming over the crest in the opposite direction. Big long straight graded dirt road with some desert shrubbery and uneven terrain to the side - the uneven terrain is what my passenger side went out into. The front passenger wheel took the majority of the force, and the axle was the only thing damaged other than the wheel pushing up enough to pop a couple fender clips. I was running 29lb wheels and 66lb 35 Patagonia MTs and other than a Steersmarts track bar, the rest of the front end components were stock at the time.

The axle bent a few degrees upwards on that side - it didn't totally break but instead the FAD housing cracked at the spot welds and the tube going from the FAD to the C was pushed upward now that it was loose from the FAD housing's spot welds. Result was some funky camber on that side but was drivable (carefully) home. This pic was from below looking up, you can see the cracked paint between the FAD and tube suggesting upward tube movement, and if you look lose on the spot weld in the top right you can see cracks surrounding it. The other spot weld was a bit worse but I can't find the other pics.

Thank you so much for taking the time to share the details. From what you posted, I'm actually a bit more reassured. Sounds like your axle survived to let you drive back rome - better than being broken on the trail.

It's possible, even likely, that the same impact would have dislodged the tube out of the diff housing on an old school non-FAD JK D44 axle, and potentially bend it even more. Sounds like the FAD tube connection provided a fuse with a shorter arm to give a little.

Also good to know the knuckle and ball joints survived the hit. I'm starting to think these D44s are actually a little less fragile than we all thing (at least that is the story I tell myself before every wheeling trip )

 

[gato]

WTF, that is just terrible. Its all about earning the badge.

Question - are the badges for the Jeep or for the driver?

I traded in my 2016 JKUR for my 2021 JLUR and I forgot to remove my badges before selling it. (Someone is driving around with my old Jeep and my old badges)

I miss having then on the side of the Jeep (P.S. my JK and JL are the same color and built similarly - viewed from the side and from a distance, most people couldn't tell the difference - to my eyes the missing badges are what I notice the most - LOL)

 

[jessedacri]

Thank you so much for taking the time to share the details. From what you posted, I'm actually a bit more reassured. Sounds like your axle survived to let you drive back rome - better than being broken on the trail.

It's possible, even likely, that the same impact would have dislodged the tube out of the diff housing on an old school non-FAD JK D44 axle, and potentially bend it even more. Sounds like the FAD tube connection provided a fuse with a shorter arm to give a little.

Also good to know the knuckle and ball joints survived the hit. I'm starting to think these D44s are actually a little less fragile than we all thing (at least that is the story I tell myself before every wheeling trip )

The axle did survive an 800 mile drive home! This happened in Moab so I had Rory Irish of Moab Motorsports check it out and he deemed it drivable as long as I wasn't going to wheel it or put it under more stress than speed-limit highway driving. I've seen at least 3-4 others on here and locally who have had the axle completely snap in half at the FAD, but I can't vouch for what caused it in those other cases.

For typical wheeling loads on harder trails I think bending is much less of a risk unless you're bouncing it or otherwise using the skinny pedal where you shouldn't be. Mine was somewhat of a special case of having to essentially dive off the path at a good clip.

 

[Rangemaster]

Question - are the badges for the Jeep or for the driver?

I traded in my 2016 JKUR for my 2021 JLUR and I forgot to remove my badges before selling it. (Someone is driving around with my old Jeep and my old badges)

I miss having then on the side of the Jeep (P.S. my JK and JL are the same color and built similarly - viewed from the side and from a distance, most people couldn't tell the difference - to my eyes the missing badges are what I notice the most - LOL)

Its about the jeep doing the badges, that is my take on it.

 

[falcon241073]

The axle did survive an 800 mile drive home! This happened in Moab so I had Rory Irish of Moab Motorsports check it out and he deemed it drivable as long as I wasn't going to wheel it or put it under more stress than speed-limit highway driving. I've seen at least 3-4 others on here and locally who have had the axle completely snap in half at the FAD, but I can't vouch for what caused it in those other cases.

For typical wheeling loads on harder trails I think bending is much less of a risk unless you're bouncing it or otherwise using the skinny pedal where you shouldn't be. Mine was somewhat of a special case of having to essentially dive off the path at a good clip.

That’s one reason I’m having an artec truss welded on when I get my gears installed

 

[gato]

Its about the jeep doing the badges, that is my take on it.

That is what I thought - so even if I had removed them, I shouldn't automatically slap them on the new Jeep.

Oh well - I only had 3 anyway - another reason to redo them.

 

[gato]

I'd love to have a bolt on axle truss that I could install myself without pulling the axle.

In theory a truss with U-bolts and such should provide some decent strengthening. Not sure why that is not a thing in the Jeep aftermarket.

I'd slap those in in an instant as insurance. Welding are too much of a commitment. Sounds too much like wedding.

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