Yet another failed axle bolt

[bloodocean]

I did. If I recall, it was around 62K miles. I know it wasn't broke long due to tire rotations and the fact I could hear it.

Mine was prior to 18,000 FWIW.

The icing on the cake is all of the Ford dealers' service departments in my area are almost criminally incompetent. I had it at my dealer, they said 1-2 day turnaround... it sat for 9 days, while they lied about status updates and performed no service of any kind (I had 2 recalls to get done at the same time). The truck has GPS and a modem, I don't know why they lie about working on it when it's plainly obvious it's sitting in the lot collecting tree sap.

Anyhow I took it back home after they stopped replying. I might need to buy a beater to wait out service next time.

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[jhelrey]

Interesting. I scheduled the drop off. Picked up the loaner. Called me 48 hours later wanting the loaner back and to grab my truck.

 

[bloodocean]

Interesting. I scheduled the drop off. Picked up the loaner. Called me 48 hours later wanting the loaner back and to grab my truck.

I ubered home on my own nickel after learning they "don't do loaners." They were much more helpful when I was buying their brand new Platty off the lot.

Where is this epic dealership you found? Could be worth a road trip if the axle holds ?‍

 

[amschind]

Bought a couple of different "Grade 8" (Metric 10.9) coated bolts.

Also looked up the typical torque settings for 12x1.75 bolts and only torqued to 84 ft lbs.

Unlike the Ford bolts, the machined threads are as clean on the bolts as the machined threads inside the axle are. You can thread the bolts in by hand. Just like you would think you should be able to. (try to thread the gnarly oem bolt by hand)

I currently have bolts from McMaster-Carr that have a black coating

There are some Dormans that are the same spec but a gold coating

On the driver's side I added a Bellville washer

On the passenger side I used a polymer washer.

Just 2 different approaches to "dampen" forces against the shear?

Anyways, as stated earlier, I removed them both at each oil change and look for any signs of fretting or deteriorating spline mating.

If you shear a bolt and don't notice it right away, you will SEE the evidence of fretting (red metallic dust) and the axle will no longer be stationary if you push/pull on it.

This last check, the axle and threads looked just like they did brand new.

Immaculate!

Have you noticed that your bolts back out? I.e. is retorquing them now a maintenance item? That is just fine to me.... I don't even run center caps on my wheels, but maybe that's a clue: Ford was so worried about deferred maintenance causing bolts to loosen that they used "sticky" threads and too much torque to keep them stationary.

 

[Snakebitten]

Have you noticed that your bolts back out? I.e. is retorquing them now a maintenance item? That is just fine to me.... I don't even run center caps on my wheels, but maybe that's a clue: Ford was so worried about deferred maintenance causing bolts to loosen that they used "sticky" threads and too much torque to keep them stationary.

I think I'm still less than 10,000 miles on my own bolts. I've checked on them 3 times?

They release at just about the same torque I torque them to. So I don't think they have budged. But theoretically, with the both the Bellville washer and the synthetic polymer washer, whatever forces are at play would be absorbed by the setup. Or at least that's how it feeeeels it would be.

 

[bloodocean]

Wonder if it's possible to rig a safety wire setup through the bolt head & lip of the hub? Better insurance than "sticky threads" I would think.

 

[Snakebitten]

Wonder if it's possible to rig a safety wire setup through the bolt head & lip of the hub? Better insurance than "sticky threads" I would think.

Definitely an option for applications where fasteners might loosen or back out.
But with this application it's a rather long bolt with no evidence of backing out. I don't use any thread locker on my bolts and they are far smoother/slippier than the grainy oem.

 

[xxlt250rxx]

Bought a couple of different "Grade 8" (Metric 10.9) coated bolts.

Why did you choose to stick with 10.9 grade bolts? Why not 12.9 bolts?

 

[Snakebitten]

Why did you choose to stick with 10.9 grade bolts? Why not 12.9 bolts?

Honestly, I was not wanting to increase hardness. That might be flawed thinking, metallurgy wise, because I don't know much about such things. But I equated hardness to brittleness?

I'm looking for less stress (torque) to avoid injuring the bolt to start with. And then providing some elasticity (thousandths) to the equation.

 

[simon]

in general you’re correct- typically the harder the material the more brittle it is. The grade of a fastener refers to strength, not hardness. A higher grade, I believe, would help this situation.

it’s been many years since I took a class in this stuff in college so it’s very possible my understanding is not correct

Honestly, I was not wanting to increase hardness. That might be flawed thinking, metallurgy wise, because I don't know much about such things. But I equated hardness to brittleness?

I'm looking for less stress (torque) to avoid injuring the bolt to start with. And then providing some elasticity (thousandths) to the equation.

 

[Snakebitten]

in general you’re correct- typically the harder the material the more brittle it is. The grade of a fastener refers to strength, not hardness. A higher grade, I believe, would help this situation.

it’s been many years since I took a class in this stuff in college so it’s very possible my understanding is not correct

Thanks for that.

As much as I have discussed the F150 Max Tow Sheared Bolt subject, I've really tried to keep it simple. My approach, that is.

Nothing more than using an alternative fastener. As well as being vigilant at checking for the slightest sign of a problem with it.

If I ever do find such evidence, I'll try a stronger spec bolt.

 

[JoeRedFly]

February '23 Build Date, after the recall dates. No issues, but replaced the bolts for insurance with Class 12.9 (Grade 9) bolts @ 90ftlbs wet. Easy enough to do while I was rotating the tires.

@Snakebitten If you're still collecting data, mine came out at less than the 30 ftlbs I had the torque wrench set to for removal. They felt like it was just the thread glue holding them in.


https://www.mcmaster.com/90373A125/

 

[Snakebitten]

February '23 Build Date, after the recall dates. No issues, but replaced the bolts for insurance with Class 12.9 (Grade 9) bolts @ 90ftlbs wet. Easy enough to do while I was rotating the tires.

@Snakebitten If you're still collecting data, mine came out at less than the 30 ftlbs I had the torque wrench set to for removal. They felt like it was just the thread glue holding them in.


https://www.mcmaster.com/90373A125/

That's amazing!
I wonder if the culprit is something as simple as the factory bolt being over torqued, and/or the bolt not the necessary quality for the official torque setting?

Who knows?
But thanks for joining the experiment.

Can I ask what torque you used for your aftermarket bolts? It's hard to put a ftlbs to it though if you follow the torque procedure the service manual calls for. I chose not to use the torque to #ftlbs, then degrees further.

I googled typical torque in ftlbs for that grade of bolt in 12x1.75 thread. In my opinion I have the bolts torqued less than factory spec.

It isn't like them falling out would be worse than shearing. ???

By the way, they don't appear to be loosening, so they are doing what the bolt should do. Locating the floating axle to the outermost location.

 

[JoeRedFly]

@Snakebitten I torqued them to 90 ft lbs which is pretty damn tight, and way tighter than the factory ones were in there. My intent was to prevent any movement and therefore wear on the splines. Time will tell if that was the right thing to do.....

 

[HammaMan]

Aren't the factory bolts TTY? Sounds like they stopped yielding them.

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