Looks like another axle bolt shear…

[notabot]

@Ries Thanks for this picture! The numbering underneath the washer shows ZERO signs of wear or rubbing by the washer. One of the running theories is axial play in the wheel bearings allow the bolt to be tilted by a small amount during normal running. This continuous movement creates the sheared bolt shaft we see in every single failure.

Now I'm wondering if the bolt is moving on top of the washer. Has anyone taken apart the failed bolt head to see if there is wear? Would you be able to punch that bolt out of the washer and take another picture of the top of the washer?

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[Ries]

I guess if it looks like nothing had moved much from where it's intended to be located, things should be just fine otherwise?

Well a few things come to mind.

Axle shaft retracts into differential. Now full load is being applied to half of the splined end of the shaft at the hub/differential, which results in either 1) splines shearing off axle at hub, 2) splines shearing off hub, 3) splines shearing off axle at differential, 4) side gear splines shearing off in differential… or any combination there of. In any case all scenarios are no bueno.

 

[UGADawg96]

So has anyone else had this issue??!!

yes

https://www.f150gen14.com/forum/threads/can-anyone-tell-me-what-this-is-part-failure-on-axle.8963/

https://www.f150gen14.com/forum/threads/f150-powerboost-axle-bolt-sheared-off.10392/

 

[Snakebitten]

Well a few things come to mind.

Axle shaft retracts into differential. Now full load is being applied to half of the splined end of the shaft at the hub/differential, which results in either 1) splines shearing off axle at hub, 2) splines shearing off hub, 3) splines shearing off axle at differential, 4) side gear splines shearing off in differential… or any combination there of. In any case all scenarios are no bueno.

That's what I meant though about catching the broken bolt but finding no evidence that the axle had moved inboard or outboard. I'm assuming that it wouldn't be difficult to visually see whether anything has moved?

 

[Ries]

@Ries One of the running theories is axial play in the wheel bearings allow the bolt to be tilted by a small amount during normal running. This continuous movement creates the sheared bolt shaft we see in every single failure.

I’m pretty convinced they have a tolerance stack issue where the bolt is too short and/or a setting issue.

Now I'm wondering if the bolt is moving on top of the washer. Has anyone taken apart the failed bolt head to see if there is wear? Would you be able to punch that bolt out of the washer and take another picture of the top of the washer?

Yes, here you go. I was able to just thread the bolt back out of the washer. Something hardened around the bolt in the washer ID.

 

[notabot]

Well a few things come to mind.

Axle shaft retracts into differential. Now full load is being applied to half of the splined end of the shaft at the hub/differential, which results in either 1) splines shearing off axle at hub, 2) splines shearing off hub, 3) splines shearing off axle at differential, 4) side gear splines shearing off in differential… or any combination there of. In any case all scenarios are no bueno.

Perfect and thank you! Now I'm more puzzled. No wear there either.

In your post above, you covered the two components involved in this failure and I agree, this is muy malo.

Now I want a new axle and a new wheel hub. Those two children are NOT playing well together.

 

[powerboatr]

my question is WHY did they use this axle? why not a full floater ? those axles are tried and true.

 

[Buyer2021]

So has anyone else had this issue??!!

This post has a table listing 76 bolt failure events (plus some repeat failures) with model year, build month, engine, and miles when discovered.

Your 12/2021 build month is near the middle of the date range reported.

Make of it what you will.

Post your info in that thread if you would like to contribute to that dataset, I update it regularly.

 

[Pedaldude]

Assuming they can get the remaining section of the bolt out of the axle.

I wouldn’t even bother with a broken bolt extractor and go straight to welding onto the stub and unscrewing it that way.

Any halfway decent weld shop can get that out in ten minutes easily. It would have to be a lift start, or scratch start TIG because HF can fry the electronics.

Some fellas have had the mechanic actually extract the bolt and replace it with the new torque spec. Similar to if you repaired it yourself. Of course this assumes that nothing has had an opportunity yet to damage the hub or tube or differential. I guess if it looks like nothing had moved much from where it's intended to be located, things should be just fine otherwise?

That’s one of the big questions, so far nobody has gotten their hands on a sacrificial hub to disassemble or section.

What’s holding the rotating and static hub elements together, if anything?

Is there play in the new ones?

What does the bolt even do?

Does driving without the bolt damage the hub? Some of the people that have only had the bolt replaced have reported what sounds like excessive runout causing brake noise from the problem side.

Other than the rendering in the workshop manual that is the same as you can see by taking your brakes off. There’s nothing to describe the 3/4 float hub’s anatomy other than some shit from a 1970’s textbook and an image of what looks like a museum display from the 60’s or 70’s.

Someone needs to get their hands on a hub and either pop it apart or cut it in half with a bandsaw.

 

[Nomis]

It's already reaching a legendary status on the forums.
Mostly reported to affect a specific range of production dates.

This is probably a stupid question for OG Ford guys, but Im new. How do you find the production date?

 

[Buyer2021]

This is probably a stupid question for OG Ford guys, but Im new. How do you find the production date?

The build month/year (the VIN-specific EPA Compliance Date) is on the white sticker affixed to your driver doorframe with info about GVWR, GAWR, etc.

It's required by law on all vehicles from all manufacturers, the exact form and content may vary.

 

[Truckstuff]

What dates do you know are seeing the axle bolt issue

 

[Buyer2021]

What dates do you know are seeing the axle bolt issue

click the link in post 23 above or the hyperlinked note below

FYI here's some 'stats' for the table of bolt failures at that link

MILES = miles when failure was discovered, miles when failure occurred is never exactly known
Note this data is subject to frequent update

 

[Nomis]

The build month/year (the VIN-specific EPA Compliance Date) is on the white sticker affixed to your driver doorframe with info about GVWR, GAWR, etc.

It's required by law on all vehicles from all manufacturers, the exact form and content may vary.

Thanks, I guess it has just never been a thing I looked in to before.

Mine was built a month before I bought it, on November 14, 2022 in Kansas

 

[Farmerj]

Definitely seems like shear. Looking at the bolt I’m guessing it was compromised at the install and then corrosion and operational vibration finished it off. This would explain why it was not seen on the assembly line.

However I know how their assembly line works. I guarantee that Ford has the installation torques documented for these axle nuts with their DC tools for ever truck manufactured. So it will nust be a matter of reviewing th

I suspect their was an error in the torque call out for their standard work and they didn’t adjust it until later on. However, I don’t know why this wasn’t caught with the initial 2021 model builds. This means that there are now thousands of impact trucks out there.

Wouldn’t want to be the engineer responsible for that oops.

If it was an over torque situation it would be a tensile break, not a sheer break.

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