I just installed Bilstein 5100s on the front of my 2015 F150. I took the shocks off and took them to a local garage to get the springs swapped over to the new Bilsteins. I reinstalled everything and have a clunking noise in the front. I found that the strut shaft nut (the center nut when looking at the top hat strut mount) is loose. Well I tried to tighten it with a wrench and a socket to hold the shaft - I couldn't even budge it and its only about 2 threads on. It looks like they reused the factory nut on there. Is there a nut that was included with the Bilstein that they should have used for this? I am worried that they forced this nut on and may have stripped the threads off. I did find a product picture that shows a washer and nut laying near the top of the shaft but want to confirm with someone who has done the swap themselves.

 

 

I called the shop that did the swap and he said there was no nut\washer - only the 2 long bolts\nuts for the bottom and the collar.
Not sure I should trust their word for it or not. Either way they probably have the top threads messed up now. They said to bring them back down and they will see what can be done.

 

Anyone know what thread size\pitch nut is needed for that?

 

I called Bilstein and the nuts and washers should have been included. The size is M12x1.5.
From the little info I could find on the OEM nut, it is M12x1.25.

This should be a fun fix.

 

 

I bought the correct nuts and washers at NAPA yesterday and went home after work to tackle this. I was able to get the jammed nut off using a pass through socket set. The threads on the strut shaft weren't messed up too bad, the nut was worse looking so I would say the shaft had the harder steel. I greased up the threads and was able to run the correct nut on completely. I double nutted it for insurance.