Right side rattle at highway speeds

[Nine29]

Had the same issue with my 2021 ST. I used hot glue to secure the underbody panels to the studs. Worked well so far...

 

[BigAnt75]

Had the same issue with my 2021 ST. I used hot glue to secure the underbody panels to the studs. Worked well so far...

This may sound dumb but can I see what you did as I’m planning to do that to mine this weekend and that sounds a lot easier to do.

 

[mitchellj22]

What size nuts and washers did you use? I’m having the same issue and it’s annoying as all hell!!

Ditto

 

[Jp1525]

Had the same issue on the right side….rattle/clicking at highway speeds and worse driving into the wind. Had to different Ford dealers look at it with no results. Thank goodness for this forum! Thanks to the responses I found that the felt cover on the under body of the car has a loose connection right under the driver’s side post between the driver’s door and the passenger door. Remove the cheap plastic connector and replaced with (I believe) a 7mm coarse threaded nut and a large washer. There is no noise now! We were very close to trading it in for another vehicle.

 

[Cdubya]

M6 nut and fender washer (stainless). I'd replace them all, even if they seem intact because they'll all lose their grip eventually