Aluminum knuckle failure

[Chocolate Thunder]

When I ordered my RCV axles in Feb, they said 12 weeks out for delivery. That will put me around May when I tear it all apart. I went with the FAD two piece version. I’m not sure if the one piece has a quicker delivery.

Where’d you order them from that said 12 weeks for delivery?

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[19 JLUR Bright Whit3]

Where’d you order them from that said 12 weeks for delivery?

It was on RCV's website. I originally ordered them through Northridge 4x4 with the 10% forum discount in Early Feb. I checked with them last week and they said may be shipping in 5 weeks. I ended up cancelling and going to Poly Performance again to save on the sales tax and shipping.

 

[19 JLUR Bright Whit3]

Hey Jeremy,

Blanket delay verbiage on their site now.

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During this time, RCV Performance working to fufill orders as efficiently as possible. Please allow for some additional lead times on all orders and warranty claims until further notice.
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[benny_rt2]

When i order my new jeep I plan to also order some basic upgrades including Reid racing knuckles, better balljoints and chromo shafts (probably CV) as part of the initial investment. Do it fast, like removing a bandaid.

 

[CarbonSteel]

When I ordered my RCV axles in Feb, they said 12 weeks out for delivery. That will put me around May when I tear it all apart. I went with the FAD two piece version. I’m not sure if the one piece has a quicker delivery.

Despite the general dislike for FAD, eliminating it on a JL/JT creates a different problem. Here from Adam's Driveshafts:

Due to Jeep changing their angles on the JT and JL Models, if you install an After Market Differential or Axle Kit that Eliminates the [FAD] front axle disconnect and the driveshaft spins full-time, it may result in a vibration and/or premature U-joint and CV failure.

 

[Rsarffs]

Looks like breaking an axle u-joint with steering clocked forces pressure against knuckle and breaking at balljoint boss weak point.

 

[19 JLUR Bright Whit3]

Looks like breaking an axle u-joint with steering clocked forces pressure against knuckle and breaking at balljoint boss weak point.

Yes, that appears to be the general consensus.

 

[jessedacri]

Despite the general dislike for FAD, eliminating it on a JL/JT creates a different problem. Here from Adam's Driveshafts:

Due to Jeep changing their angles on the JT and JL Models, if you install an After Market Differential or Axle Kit that Eliminates the [FAD] front axle disconnect and the driveshaft spins full-time, it may result in a vibration and/or premature U-joint and CV failure.

There's no solve for this? The JL is fundamentally not able to lose the fad and have an aftermarket driveshaft that doesn't wear prematurely? I feel like the angles aren't crazy far off from other stuff out there, am I missing something here?

I have an Ultimate 44 axle up front that doesn't have a fad and the stock FCA driveshaft does not vibrate, the CV side flange is all bent up though from being at full flex a lot and I need to replace it soon. Hope to go with something that isn't going to vibrate, that's for sure.

 

[19 JLUR Bright Whit3]

There's no solve for this? The JL is fundamentally not able to lose the fad and have an aftermarket driveshaft that doesn't wear prematurely? I feel like the angles aren't crazy far off from other stuff out there, am I missing something here?

I have an Ultimate 44 axle up front that doesn't have a fad and the stock FCA driveshaft does not vibrate, the CV side flange is all bent up though from being at full flex a lot and I need to replace it soon. Hope to go with something that isn't going to vibrate, that's for sure.

I'm thinking its hit or miss on an aftermarket DS and Adams has to put that out there for the possibility of vibration on a live axle. My $.02

 

[CarbonSteel]

There's no solve for this? The JL is fundamentally not able to lose the fad and have an aftermarket driveshaft that doesn't wear prematurely? I feel like the angles aren't crazy far off from other stuff out there, am I missing something here?

I have an Ultimate 44 axle up front that doesn't have a fad and the stock FCA driveshaft does not vibrate, the CV side flange is all bent up though from being at full flex a lot and I need to replace it soon. Hope to go with something that isn't going to vibrate, that's for sure.

The angles on the JL are much "tighter" than previous versions--but it could be the UD44 improved those angles, but that can depend on the lift height too. I can say that when I had issues with the DS CrMo axles where they seized between themselves inside the FAD and the driveshaft turned all the time, there was a ton of vibration that I'm sure would have caused premature wear. Aside from that, the vibration was not tolerable for long distances. I'm glad I sorted it with RCV axle shafts. I personally like the FAD and wanted to keep it.

 

[19 JLUR Bright Whit3]

There's no solve for this? The JL is fundamentally not able to lose the fad and have an aftermarket driveshaft that doesn't wear prematurely? I feel like the angles aren't crazy far off from other stuff out there, am I missing something here?

I have an Ultimate 44 axle up front that doesn't have a fad and the stock FCA driveshaft does not vibrate, the CV side flange is all bent up though from being at full flex a lot and I need to replace it soon. Hope to go with something that isn't going to vibrate, that's for sure.

I believe the ponytail Asian Youtuber has your axle and was fine with an aftermarket DS.

 

[bjm00se]

The owner of the Jeep and some here are linking "not using lockers" to the bouncing.

I'm with you on being unlocked not necessarily being a *cause* of bouncing.

But in the presence of asymmetric bouncing, with lockers not engaged, the unloaded wheel can pick up more wheelspeed, and thus have a lot more rotational kinetic energy that can be translated into causing damage when the bounces end and the wheel loads up again.

 

[gato]

I'm with you on being unlocked not necessarily being a *cause* of bouncing.

But in the presence of asymmetric bouncing, with lockers not engaged, the unloaded wheel can pick up more wheelspeed, and thus have a lot more rotational kinetic energy that can be translated into causing damage when the bounces end and the wheel loads up again.

Agreed.

But conversely, when unlocked the load from a wheel that suddenly lands and gains traction (chock) is mitigated by the open diff offering - i.e. the open diff allows for, well, different speeds between the two wheels/axles shafts. When you are locked, you make everything into a mechanical connection with no play - when one side stops the load goes solidly everywhere - one component will loose.

 

[bjm00se]

Agreed.

But conversely, when unlocked the load from a wheel that suddenly lands and gains traction (chock) is mitigated by the open diff offering - i.e. the open diff allows for, well, different speeds between the two wheels/axles shafts. When you are locked, you make everything into a mechanical connection with no play - when one side stops the load goes solidly everywhere - one component will lose.

Yep.

As usual, the situation on the ground determines the outcome.

Folks who "always turn on their lockers" or "never turn on their lockers" are oversimplifying.

Right tool for the right job at the right time.

 

[Headbarcode]

Despite the general dislike for FAD, eliminating it on a JL/JT creates a different problem. Here from Adam's Driveshafts:

Due to Jeep changing their angles on the JT and JL Models, if you install an After Market Differential or Axle Kit that Eliminates the [FAD] front axle disconnect and the driveshaft spins full-time, it may result in a vibration and/or premature U-joint and CV failure.

I'm thinking its hit or miss on an aftermarket DS and Adams has to put that out there for the possibility of vibration on a live axle. My $.02

Dana is welding the inner C's according to Jeeps caster specification. Since many of us are finding better handling with more caster, that's putting the pinion at a lower angle. Couple that to a lifted Jeeps increased driveshaft angle, and vibration becomes a concern at highway speeds and a locked front axle in 2h.

I opted for the 2-piece RCV axle set to avoid that likely vibration. I have zero inclination to ditch the FAD until I upgrade to a larger set of axles with manual locking hubs.

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