Stop/start/change direction clunks - FIXED

[dermot]

Issue overview:

Both my 2024 F-150 Lightning (my truck) and my wife's 2023 Mustang Mach-E developed noises when stopping and starting.

• Mustang Mach-E: Emitted a distinct clunk and it came from the back.
• F-150 Lightning: Emitted a 'ting' or click, often when changing direction. This was particularly noticeable with the windows down while navigating roundabouts and corners and was coming from the front.

Root Cause and Visual Evidence

The source of the noise on both vehicles was loose and corroded axle nuts (also known as spline, spindle, or half-shaft nuts). The larger motors in these vehicles—front for the Lightning, rear for the Mach-E—put significant stress on these components.

Reference the attached file Axel nuts.png for a visual comparison:

• Left side: Lightning nuts (heavy corrosion is visible on the top two).
• Right side: Mach-E nuts (the bottom right pair are from the rear axle, which houses the more powerful motor).

Repair Procedure and Specifications

Following Ford's official service procedures (some details in the attached file Lightning Axel.png), the fix requires replacing the hardware.

• Remove the old nuts and discard them.
• Apply Loctite to the threads and install the new wheel hub nuts.
• Critical step: Tighten the nuts using a torque wrench in one continuous rotation. Always install a new wheel hub nut after loosening or if not tightened to specification in a continuous rotation, otherwise damage to the components may occur. Do not use an impact gun; continuous rotation is required to generate the necessary friction. Applying the brake (for the front) and parking break for the rear will keep the halfshaft from rotating during this process.

Torque Specifications

• 2023 Mustang Mach-E: 150 ft-lbs.
• 2024 F-150 Lightning: 258 ft-lbs.

(above is for the F-150 Lightning)

Conclusion

The noises on both vehicles disappeared immediately after completing this repair.

References

Ford Motor Company. (2026). Motorcraft service information. Motorcraft Service. https://www.motorcraftservice.com
Ford Motor Company. (n.d.). Front disc brake, removal and installation (206-03) [Service manual excerpt]. Lightning Axel.png.
User provided photograph. (n.d.). Corroded axle nuts. Axel nuts.png.

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[Artifex]

How on earth did you figure this one out? Or is this a known issue?

 

[gavine]

How on earth did you figure this one out? Or is this a known issue?

It's a known issue. Ford actually has a new part# for the nut that has thread locker on the threads.

 

[Artifex]

Good to know. Thanks.

 

[dermot]

It's a known issue. Ford actually has a new part# for the nut that has thread locker on the threads.

There was thread locker on the passenger side of our Mme. not the driver side.

 

[AndyPugno]

Is there a service bulletin on this?

 

[dermot]

Is there a service bulletin on this?

Not that I'm aware of, but there should be! Obviously quality control is an issue in my car's case because only one side (2 of 4) axels had thread locker. It was white and made it quite difficult to remove the nuts... the driver side was super easy.

 

[Corey_lax]

I snugged up my existing nuts a couple weeks ago and it made no difference. The click still persists. I did just order new nuts with the loctite and will try that tomorrow night hopefully. Maybe taking it right off and putting the new ones on will fix it up.

 

[dermot]

I snugged up my existing nuts a couple weeks ago and it made no difference. The click still persists. I did just order new nuts with the loctite and will try that tomorrow night hopefully. Maybe taking it right off and putting the new ones on will fix it up.

Just make sure you clean up the wheel hub surface that the back of the nut tightens down on - I didn't hear -- but did after this picture. Need to remove any corrosion to make sure the surface can grip enough. You can see the blue loctite on the thread.

 

[Corey_lax]

Just make sure you clean up the wheel hub surface that the back of the nut tightens down on - I didn't hear -- but did after this picture. Need to remove any corrosion to make sure the surface can grip enough. You can see the blue loctite on the thread.

Sounds good! Finally get to use my Milwaukee die grinder lol

 

[dermot]

Sounds good! Finally get to use my Milwaukee die grinder lol

that's my truck vs. the Mach-e -- but same idea! . (in case someone counts the lug threads) ha ha. Also the Mach-e nuts don't have the plastic insert on the nut.

 

[Bluestang]

Not that I'm aware of, but there should be! Obviously quality control is an issue in my car's case because only one side (2 of 4) axels had thread locker. It was white and made it quite difficult to remove the nuts... the driver side was super easy.

Lock tight on one side to counter the tourney from wheel start stop from loosening nut. One side tightens and one side loosens.

 

[Corey_lax]

Lock tight on one side to counter the tourney from wheel start stop from loosening nut. One side tightens and one side loosens.

What if you reverse a lot?

 

[McSquashy]

I found that torquing my factory nuts a smidge helped eliminate the clunk... At least for a short while. I noticed today that it's starting to come back.

Looks like I'll be ordering up a new set of nuts and trying that next. I'll also be sure to inspect for and remove any corrosion first.

Thank you @dermot for the post!

 

[dermot]

Lock tight on one side to counter the tourney from wheel start stop from loosening nut. One side tightens and one side loosens.

Well, I think you just explained it! Thanks, that makes sense! I wonder if they'll do a reverse thread in the future on the passenger side to elevate the problem.

So weird on my Lightning how the driver side was so corroded and clicky.

Thanks for the insight on this.

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