Just recently installed a set of Spax coilovers, and there's a rattle that sounds like metal bumping metal on the front passenger side. After some diagnosis, it appears that the top spring mounting plate has about a 2-3mm gap to the strut shaft. I had made sure that the strut piston nut is on as far as it will go, using an impact wrench, and there was no gap there before I mounted it back into the suspension. The spring height hasn't changed, either. I've already taken it apart once to re-check that the piston nut is in as far as it will go. Am I missing something here?

Here is a photograph of the gap between the top mounting plate and the strut shaft:

 

You might check to see if washer #6 in this diagram is there.
http://www.realoem.com/bmw/showparts...41&hg=31&fg=10

 

The coilovers came with a washer similar to #6 in the diagram, and that was what I used. I don't think I'm missing any parts, as this problematic front passenger strut was done in the exact manner as the front driver strut, which does not exhibit the gap.

Thanks for chiming in!

 

Are you sure you put the assembly back together? Some of the washers are beveled, and if you put them on upside down or leave them out like Th3118 stated, it will have some flukes in the set up. Just check to make sure all the washers are there or in the right place.

 

Thank you - I'll take it apart and inspect it again. I wanted some feedback before removing the strut yet again to make sure I'm not missing something blatantly obvious that I just hadn't considered. :impatient

I suppose it also couldn't hurt to compress the spring a bit while tightening the piston nut down to ensure there's no gap, but like I stated earlier, I followed the exact same steps for both the driver's side and the passenger side, and only the passenger side is exhibiting the gap and causing the rattle.

 

Quick thought - might the lack of the OEM bumpstops cause this rattling issue? The Spax installation instructions (finally found a copy floating around online) don't specify the use of washer #6, but does specify retaining the OEM bumpstops.

I appreciate anyone who has the time and experience to answer this.