Yet another failed axle bolt

[FaaWrenchBndr]

Respect. Taking it as it should be taken and not getting mad or defensive. Being accountable.

Thank you

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[FaaWrenchBndr]

You're not the only one, I've built and had many rear ends apart also, this collateral damage doesn't make sense. Spider Gears have a center pin that at least in my experience keeps the shafts from working too far inboard off the diff splines. Maybe Ford did away with that redundancy and saved a bit of material off that pin and our assumptions are wrong?

that or the spline length at the hub are too short. Just makes no sense…..

 

[HammaMan]

My guess is that there's a bit of a taper and when only ~1" of 3 or so remains that's slightly tapered it ends up being ~15% or so of remaining strength left. It's simply a matter of time. It showed up first in the powerboosts due to their significantly higher torque load down low (plus regen helps work it back and forth each braking cycle). One guy was towing and well that's a for-sure torque spike. The manual says its a press fit but the evidence so far appears that it's not the case. Granted excessive wheel bearing heat may just let it loose. Even then there needs sufficient force for it to migrate into the diff. Quite a few theories and an exceptionally long lead time for the fix which isn't supposed to show up for another 7 months or so.

The oddest part of this is that ford is STILL shipping trucks with this axle.

 

[FaaWrenchBndr]

My guess is that there's a bit of a taper and when only ~1" of 3 or so remains that's slightly tapered it ends up being ~15% or so of remaining strength left. It's simply a matter of time. It showed up first in the powerboosts due to their significantly higher torque load down low (plus regen helps work it back and forth each braking cycle). One guy was towing and well that's a for-sure torque spike. The manual says its a press fit but the evidence so far appears that it's not the case. Granted excessive wheel bearing heat may just let it loose. Even then there needs sufficient force for it to migrate into the diff. Quite a few theories and an exceptionally long lead time for the fix which isn't supposed to show up for another 7 months or so.

The oddest part of this is that ford is STILL shipping trucks with this axle.

quite possible.

Thank you for your insight and thoughts. I appreciate it, well done, sir

 

[simon]

This is unfortunate. Has anyone tried extracting the broken part of the screw and replacing? In my head this seems like a relatively easy fix, but drilling a grade 10 screw also seems like a daunting task. Also, does anyone know the part number for this screw?

 

[Buyer2021]

My guess is that there's a bit of a taper and when only ~1" of 3 or so remains that's slightly tapered it ends up being ~15% or so of remaining strength left.

Quite likely, IMO, given that the Ford service procedure calls for using a hydraulic press to seat the axle into the hub before installing the bolt (IOW, the spines are not a slip-fit on the hub-end as they are on the differential end).

 

[oncechance]

This is unfortunate. Has anyone tried extracting the broken part of the screw and replacing? In my head this seems like a relatively easy fix, but drilling a grade 10 screw also seems like a daunting task. Also, does anyone know the part number for this screw?

Maybe @Snakebitten can chime in. I believe he tried but could be mistaken.

 

[jhelrey]

How many people are out there driving around with a broken bolt?

My dealership did give me a loaner.

 

[Snakebitten]

Maybe @Snakebitten can chime in. I believe he tried but could be mistaken.

I'm not a master mechanic by any means, but I have been around for a very long time and have wrenched on my own machines since I was a pup. Got tools too.

I absolutely believed that I was going to succeed at extracting that sheared bolt out of the axle. Spent the time, effort, and more than a few techniques. And yet I ended up crying U.N.C.L.E (I told you I am old ?)

Perhaps not all sheared axle bolts are the same and so some might not be equally stubborn? But I ended up just letting the dealership throw 2 new axle/hub assemblies on the truck and I promptly went home and swapped the new bolts out for 2 alternative machined bolts. Which I have checked on a couple of times and all seems well.

 

[simon]

Yeah... I am mostly concerned with removing the screw remains. What gave you trouble with the extraction? I imagine the screw is loctited in from the factory which will give the extractor grief too.

I will call around to other dealers in the area tomorrow, but not having anything to drive for 5+ days will be a huge problem

I'm not a master mechanic by any means, but I have been around for a very long time and have wrenched on my own machines since I was a pup. Got tools too.

I absolutely believed that I was going to succeed at extracting that sheared bolt out of the axle. Spent the time, effort, and more than a few techniques. And yet I ended up crying U.N.C.L.E (I told you I am old ?)

Perhaps not all sheared axle bolts are the same and so some might not be equally stubborn? But I ended up just letting the dealership throw 2 new axle/hub assemblies on the truck and I promptly went home and swapped the new bolts out for 2 alternative machined bolts. Which I have checked on a couple of times and all seems well.

 

[Snakebitten]

Yeah... I am mostly concerned with removing the screw remains. What gave you trouble with the extraction? I imagine the screw is loctited in from the factory which will give the extractor grief too.

I will call around to other dealers in the area tomorrow, but not having anything to drive for 5+ days will be a huge problem

Why would you need to be without the truck for 5 days? I thought the dealerships stopped being silly on this procedure.
They take a picture of the broken bolt and submit it with the parts order in the TSB. The parts could easily be there next day if they don't already have them.
The swap itself is measured in minutes. Less than 1 hour per side.

The factory screw is red loctite.
And the factory screw has some kind of granular anti-corrosion coating/treatment that really does a number on the thread precision with the threads of the machined axle.
The axle threads are beautiful and smooth. The bolt borders on gnarly, by comparison. You aren't threading the factory bolt into the axle very far with your fingers, yet I can thread 3 different bolts I purchased after market and it's smooth as nice machining would suggest.

 

[simon]

The factory screw is red loctite.
And the factory screw has some kind of granular anti-corrosion coating/treatment that really does a number on the thread precision with the threads of the machined axle.
The axle threads are beautiful and smooth. The bolt borders on gnarly, by comparison. You aren't threading the factory bolt into the axle very far with your fingers, yet I can thread 3 different bolts I purchased after market and it's smooth as nice machining would suggest.

Thanks for your input. I think extracting it may be impossible like I'm concerned about.

The dealership told me they have to order the part, but can't order it unless the truck is in the shop and the part is a 5 day lead time. He also said they have no loaners available and ford won't authorize a rental. They have "no avenue to help". I'll call other dealers in the Atlanta area tomorrow

Simon

 

[Snakebitten]

They do in fact have to have the truck to take the picture.
But there's absolutely no reason you can't drive the truck until the parts arrive.

Surely they know that these trucks often go thousands of miles and perhaps weeks/months being driven daily with a sheared bolt?

What’s happened to even the common decency of NOT making the customer experience unnecessary inconveniences? There's no reason to leave your truck sitting in a parking lot.

Nor do I believe they know for a fact that it would be 5 days before they receive the part. Ford supposedly expedites this order if it is put in properly.

 

[HammaMan]

Pulling off the hub should allow the axle to slide out. If the failure is like most others, it should have a nice little spot to use a CCW drill bit on it. Heat up the axle quite a bit and drill it. If it's not centered you'd need a lathe and mill end to rectify that. A machine shop could do it in 10 minutes or so.

 

[Hog_Johnson]

I emailed my dealer a pic of the broken bolt and they ordered new axles without me taking it in. The parts only took a couple days to show up.

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