suspension knock

stevexesther · Post by **stevexesther** » Wed 04 Jul, 2007 20:19

Hi All
Hope someone can help, i have had my 2004 Z4 3.0si roadster for a couple of months now and have become very aware of suspension knocking and banging over rough surfaces. i am aware that the ride can be a little unsettled over rough surfaces but did not expect so much knocking and to top it off, if it has been parked up for a couple of days the rear-brake tends to stick on after releasing the handbrake, along with the weather I am starting to think I have made a massive mistake but there you go what the hell. Anyway after whinging so much has anyone else had this type of problem or is it me imagining things.
Your help would be greatly appreciated.
Cheers
Steve

Ian in Lancs · Post by **Ian in Lancs** » Thu 05 Jul, 2007 05:34

if the knock is coming from the rear take a look at the coil springs they have a tendancy to break a couple of coils off, esp the RHS for some reason. My theory is stones hitting the low set coils, penetrating the protective coating, causing a rust spot and stress point from which the crack radiates and causing failure. I had mine replaced under warranty (zforum had a long list of owners that had this problem). You can check yourself by jacking the rear a little and seeing if the coil is complete on both sides. As for the brake binding - on the z4 the hand brake operates shoes inboard of the discs and these sqeak against the backplate - again a comon problem; sound like yours are dry to the point of binding. Cured by lightly lubing the backplate with grease suitable for brakes; copperease or something. Do you have warranty if so they could be done easily at the same time.

stevexesther · Post by **stevexesther** » Thu 05 Jul, 2007 17:48

Your comments are vey interesting Ian and thanks for the advice, although the suspension knock is coming from the front, luckily i have a BMW warranty, I will get it booked in and let you know the outcome.
once again thank you very much for your assistance

Steve

Sephanite · Post by **Sephanite** » Fri 06 Jul, 2007 15:18

i had the same knocking sound from the front aswell and ignored it for quite a while. When i got it checked, i had to get my shock rebuilt as (the reason) during heavy driving, water vapour seeped into the shocks as the shocks got heated via heavy driving and mixed with the liquid inside the shock. I am not sure how much is true but the sound disappeared after the rebuild