2022 F150 Rear Axle exploded... Ford tech said "3rd one this week"

[HammaMan]

By the way, this is why I have them on hand. If I ever discover the broken bolt, and the dealership doesn't have the axle on hand for the repair, I'm drilling it out and rebolting while I wait.
Or at least that's one strategy.

What's the grade marks on those heads? Still can't believe there's enough force to pop those heads off.

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[Snakebitten]

What's the grade marks on those heads? Still can't believe there's enough force to pop those heads off.

I don't remember the grade off hand.
M18 258ftlbs

If it's true that there's a thread mismatch, perhaps the bolt is injured upon assembly, and it's basically ready to pop with very little stress compared to what it otherwise could handle?

 

[Ed21]

This is the first thing that came to mind. Failed bolt, axle migrated in until remaining spline engagement was such it could no longer take the torque and twisted em to nothing.

Ford best be eating this repair due to known design flaw.

I understand the bolt keeping the axle from moving inbound, sounds like the pinion pin is too far away to keep it from moving too far from destroying the splines at the hub. (Must not be much meat there). Since there are no C clips in the differential, what keeps the axle from migrating outward other than the cap in the center of the wheel? And doesn’t the pinion pin on more conventional designs keep the axle from inward migration causing the C clip to drop out? I have a mechanical background, but not auto mechanics. I’m just trying to get a grip on this max tow design.

 

[Ed21]

Nevermind the outward migration question, I see the axle size increase in the photo. One would think it would be the same on the inboard part of the axle.

 

[HammaMan]

I don't remember the grade off hand.
M18 258ftlbs

If it's true that there's a thread mismatch, perhaps the bolt is injured upon assembly, and it's basically ready to pop with very little stress compared to what it otherwise could handle?

It's a beast -- a 3/4" grade 8 has a proof load over 20 tons for an idea of the force that's breaking that damn thing.

 

[Buyer2021]

It's a beast -- a 3/4" grade 8 has a proof load over 20 tons for an idea of the force that's breaking that damn thing.

As you probably know, cyclic stress with even very minute flexing can lead to metal fatigue, rendering 'proof load' values meaningless.

 

[HammaMan]

As you probably know, cyclic stress with even very minute flexing can lead to metal fatigue, rendering "proof load' values meaningless.

But it's a floating axle!? Curious how well that hub holds up and if it allowed any flexing to occur leading to premature failure? The only non HD axle I saw broke was a raptor trying to crawl a rock V in moab. C-clip said nope.

 

[rtf150]

https://www.f150gen14.com/forum/threads/what-did-you-do-to-your-f-150-today.1314/post-380651

I tracked down a Fordbot and asked the question…

its @Snakebitten fault. He pushed me over the edge with his comment.

https://www.f150gen14.com/forum/thr...tech-said-3rd-one-this-week.19644/post-380620

 

[Snakebitten]

But it's a floating axle!? Curious how well that hub holds up and if it allowed any flexing to occur leading to premature failure? The only non HD axle I saw broke was a raptor trying to crawl a rock V in moab. C-clip said nope.

The fact Ford acknowledges that there's ~17,000 trucks built at both plants, within a specific date range, that are affected by faulty axles, implies they have identified that something is not right about the axles in those trucks. Which also implies that trucks before and after those aren't expected to have axles with the manufactured defect.

They also instruct the mechanic to verify the part number of the replacement to make sure it's the later (newer?) design?

Just conjecture on my part, but that bolt looks more than sufficient to do the job of "locating/holding" the axle in position to the hub. There must be something that took place during machining or assembly that injured that bolt, rather than the truck injuring it during use?

 

[fordtruckman2003]

Something machined wrong somewhere.
Axle a hair too short so the bolt is under excess stress when torqued down?

 

[slanker7]

I sincerely hope not, wishing the best for you.

BTW, maybe I missed it in the thread but what engine do you have (3.5EB, 5.0, PB)? Just curious.

I have the 5.0

 

[HammaMan]

I have a feeling this only shows up in the piggyboosts more because they're heavier to begin with. I'd be willing to bet all axles up until they did whatever they did, if they even did anything (axle disappearing suggests not), are a matter of when, not if.

 

[FORDTEXAS]

I have the Max Tow Package. Headed to the dealer now to pick it up. Will post the repair invoice later this evening

my guy.. thanks to you i can’t go to sleep at night now ?

 

[Gros Ventre]

The fact Ford acknowledges that there's ~17,000 trucks built at both plants, within a specific date range, that are affected by faulty axles, implies they have identified that something is not right about the axles in those trucks. Which also implies that trucks before and after those aren't expected to have axles with the manufactured defect.

They also instruct the mechanic to verify the part number of the replacement to make sure it's the later (newer?) design?

Just conjecture on my part, but that bolt looks more than sufficient to do the job of "locating/holding" the axle in position to the hub. There must be something that took place during machining or assembly that injured that bolt, rather than the truck injuring it during use?

I've long thought that the issue with the bolts failing is one of brittle failure. In other words the metal of the factory bolt is not properly hardened thus failing from brittleness. I take that Ford specifying verification of the newer bolt by part number to be likely that kind of failure.

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