I had the same issue and it was a bad strut. No leaks and seamed to work fine, but it was indeed the strut at the end of the day.

 

Automobile March edition, testing the BMW 535i - this after damaging and replacing the tires, "The 535i's suspension is an all-or-nothing affair: either it absorbs everything, working brilliantly to control body motions and absorbs the nastiest of road grit, bumps, and heaves; or it runs out of travel, crashing violently into the bump stops"

Does this sound familiar????

 

Having my car worked on right now at GST and they confirmed it for me - blown strut. Looks fine otherwise, visually. Anyone know how much and how long it might take to rebuild a strut if I send it off to Bilstein? $770 is hard to swallow for a single strut... but the time and effort it takes to take the darn thing off, send it off, and be w/o a car... ugh.

 

check the bilstein website... i think it is $75 per corner for a rebuild.

my front right blew out just before 60k miles, mitsu replaced it under warranty. once that side was quite i could hear the other side popping the same way, just not as bad. they denied the warranty work on the other side.

who replaces one shock anyways?

 

While gettign the rebuild done, substitute an original if you still have them.

 

Luckily I still have my original struts and springs!

I am thinking about sending the whole set and having them all revalved - or at least have the two front ones revalved at the same time, just for consistency's sake. I have Robispec springs on them currently, if I send them with the springs to Bilstein can they valve them correctly to the springs? Do I have to give them any specs?

 

You tell Bilstein the max rate of the spring. They do the rest.