[s-cars] Fw: Suspension Problems in 94 S4

[Rich Assarabowski]

Randy:

Bilstein struts are prone to early failure in these cars.  If you've eliminated all other sources of clunking it could very well be a defective strut, as it was in my case.   The check is very simple -- follow the procedure in Bentley for removing the strut.  This is done with the car on the ground, you remove the strut mount and and allow the strut to extend.  There's no need to remove the strut from the housing, that's as far as you need to go.  At this point it's just the car weight keeping the spring compressed, so you don't lift the car!   Move the strut laterally and if there's any play in it (this will create the clunk which you'll hear very clearly), you have a defective strut.  To align the strut back into position you can raise the car SLIGHTLY to take the load off the suspension, but not enought for the spring to extend and pop out.
 
The good news is the Bilsteins have a lifetime warranty.   Zygmunt Motors who I bought the struts from replaced them with no hassle.  I took the opportunity to send the new struts to Bilstein for revalving (I kept the compresssion the same, increased rebound by 40%).  The difference with the H&R V8 springs was very noticeable, the ride actually improved a lot (less pounding on bad roads) and the car felt tighter.
If you end up pullling the struts and putting in new ones, I would follow a recent recommendation on this list to drill a hole in the low point of the housing for drainage.   There's some suspicion that the housings may be filling up with oil and blocking a vent hole in the strut bottom, apparently they're designed to be open. 
 
-- Rich A.
    ex-'93 S4
    ex-'92 S4
    '08 Mazda MS3
    '99 Miata (CS autocross)