I have a set of KYB AGX struts on my 04 WRX. I heard some where that everytime you remove the strut nut at the top of the strut that you needed to replace it with a new one. I belive there is a subaru document saying this. If anyone can direct me to this document or if you have any helpful information I would really appreciate it.

 

It is a self locking nut. Technically it should be replaced, along with the nuts that hold the top hat to the chassi. Actually, I'd bet that these nuts never get replaced unless you have this done at a dealer.

 

I have had some issues with rattling so i have removed them a couple times so far. I just had the dealership remove them and put on different top hats to fix the problem. At first everything was cool but just over a weeks time i can tell it has gotten loose again. My guess is these nuts are coming loose. The dealership claims that I don't have to replace them though.

I remember finding some subaru documentation stating that everytime they remove the nut they needed to replace it.