Yet another failed axle bolt

[Snakebitten]

I hope you are correct.

I am simply pointing out Ford did something. We just don't have any information regarding.

If there had been no effort spent inside the conference room at Ford, no decisions of any kind made, no changes of any kind in manufacturing, supply, assembly........
How would we explain the obvious drop in number of sheared bolts?

It's very similar to the exhaust heat exchanger. Ford obviously did SOMETHING. We just aren't recipients of the memo. Lol

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[HammaMan]

The lack of reports could be due to people googling it and getting it in to be replaced. When google provides answers, not everyone creates an account to share it -- typically frustration driven / lack of answer. Quite a few vehicles are within the recall period ready to pop the bolts. Given repeat offenders, perhaps some axle housings aren't perfectly straight. No telling how many ford engineers came by dealers to take a look at the housings when trucks came in to take some measurements.

 

[simon]

In case anyone's wondering, I FINALLY got my truck back after it's been at the dealer with no loaner. Paperwork indicates both axle shafts were replaced, despite a failure only in the right hand side.

 

[Snakebitten]

So how long did they have the truck?

 

[simon]

So how long did they have the truck?

16 days. Major inconvenience, but not as bad as some other folks, I suppose.

 

[FaaWrenchBndr]

16 days. Major inconvenience, but not as bad as some other folks, I suppose.

Could you post the part numbers of the axle assemblies?

thanks

 

[Snakebitten]

16 days. Major inconvenience, but not as bad as some other folks, I suppose.

Not the worst, I agree.
But far longer than it should be these days. I sheared one and would have gotten it back with 2 new assemblies in 2 days if the parts order would have followed the directions properly the first time.

 

[simon]

Could you post the part numbers of the axle assemblies?

thanks

Sure - here are all of the parts that were replaced:

• qty. 1: ML3Z-4234-J Shaft assembly
• qty. 1: ML3Z-4234-H Shaft assembly
• qty. 1: XY-75W85-QL Gear Oil
• qty. 4: -W718680-5439 Bolt

 

[amschind]

I have changed my mind on wanting Max Tow. "A guy I know" read the internet and determined that the IH 82 combine weighs about 2500#. "He" neglected to read his copy of the International Harvester instruction manual, where International Harvester had cleverly concealed the actual weight of the combine, which was 3850#. This "guy" also guessed that a 102" car hauler weighs "about the same" as an 83" utility trailer. Finally he completely failed to account for the fact that cross ties and an aftermarket pickup head also have relevant mass. My "friend" is not very smart, and decided, based upon his arithmetic, that he would require only the hitch portion of his Equalizer hitch, keeping the rest of it safely at home.

Fast forward, and after Carolina Leaning "his" way from Iowa to Oklahoma, "he" is feeling quite good. "He" then found a certain highway too bumpy, and elected to take a "shortcut". This "shortcut" proved to be (very nicely paved, probably because only crazy people drive on it) 12' wide snake path through the Winding Stair Mountains. "He" was several miles into said snake path before realizing that nothing larger than a unicycle could turn around, so he white knuckled it through 70 miles of foggy 2 lane mountain roads. He noted that had he looked at the topography, he would've seen that while the ROAD travels generally north/south, the intervening branch of the Ouachita Mountains runs east/west, and that the road curves about accordingly as it traverses them.

I am happy to report that my "friend" survived, and that while he has found religion, he is not any smarter. "His" truck is built VERY similar to mine, right on down to the paint and the fire hydrant scar on the front passenger door, and "he" no longer believes that Max Tow is necessary. "He" also now has a much lower threshold for calling a hotshot trucker.

 

[FaaWrenchBndr]

Sure - here are all of the parts that were replaced:

• qty. 1: ML3Z-4234-J Shaft assembly
• qty. 1: ML3Z-4234-H Shaft assembly
• qty. 1: XY-75W85-QL Gear Oil
• qty. 4: -W718680-5439 Bolt

Damnit, looks as if they are still using the same axle part numbers.

 

[Buyer2021]

Damnit, looks as if they are still using the same axle part numbers.

No surprise here, per Ford & NHTSA it's still an "Interim Service Action" pending a "final remedy" ....

 

[Snakebitten]

The assembly part # could be the same and yet have a different bolt and/or torque spec?

It's entirely possible that the many hundreds of thousands of trucks that haven't sheared a bolt are equipped with the same part# assembly?

 

[amschind]

I really appreciate the picture, but I still don't understand exactly what that bolt is doing. The loss of that bolt clearly doesn't cause the axle to shoot out of the truck like a PT boat launching a torpedo, but I suspect that Ford put it there for a reason (thought my faith in that assumption has worn real thin). If it w ere a material science or quality control issue, Ford would almost certainly have just ponied up for Unobtanium XX1233Y and been done with it; it appears that the original bolts were not the issue, which suggests that no material with those dimensions would reliably stay in one piece.

I wonder if this is intermittent shock loads, the bolt cross section is simply too thin, or some other bizarre issue. Again, if there were so much force that no bolt could survive there, how come the catastrophic failure of the bolt just results in.....nothing?

 

[Snakebitten]

The bolt "locates" the axle to the furthest point outboard in the spline portion.
Literally, it just holds it from sliding inboard, which it can do if the bolt is sheared. It can move about 3/4-1 ".

It appears that if it moves inboard the full 3/4-1", that the reduction in spline surface mating is enough to lead to spline failure.

I've removed and retorqued that bolt enough times that I still can't understand why the torque spec is so high. Nor why the OEM bolt is so corsely manufactured.

Another picture of the assembly

 

[amschind]

The bolt "locates" the axle to the furthest point outboard in the spline portion.
Literally, it just holds it from sliding inboard, which it can do if the bolt is sheared. It can move about 3/4-1 ".

It appears that if it moves inboard the full 3/4-1", that the reduction in spline surface mating is enough to lead to spline failure.

I've removed and retorqued that bolt enough times that I still can't understand why the torque spec is so high. Nor why the OEM bolt is so corsely manufactured.

Another picture of the assembly

That's almost more confusing to me based upon my cave man understanding of floating axles. Isn't the entire point of the "3/4 floating axle" to have more bearings in order to better resist the loads of heavy towing/hauling? My recollection is that the bearing are also conical, such that they should resist sliding along the shaft axis in either direction. If Ford put a whole other bearing into the axle, how does that result in a problem keeping it form sliding along its axis vs the 1 bearing of the regular axle? Ford also does not have this issue on Superduty trucks, so clearly they know how to design an axle. Is this axle just an example of a hybrid manifesting all of the flaws and none of the virtues of its parents?

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