Clunking noise
Q
My 2005 BMW 535d has got a strange clunking noise from the front when hitting potholes and some uneven road surfaces, and also when driving onto our drive. I tried to record the noise, but it didn’t really work.
The noise is a clunk rather than a metal-to-metal noise. It sounds like something is moving but is still insulated in some way. I had both front wheels off and checked the various arms and joints and everything looked OK. I can only replicate the noise by driving onto our drive by getting both wheels to hit the slightly raised kerb at the same time.
If I drive at an angle with one wheel hitting first the noise is nowhere near as evident or not there at all. When the front of the car was jacked up one side at a time there was a large gap (big enough to slide a large cable tie through) between the anti-roll bar and the anti-roll bar bush.
I presume these bushes are meant to be a very snug fit. Due to this the first things I was going to try changing are the anti-roll bar bushes and whilst I’m at it the droplinks as I know from previous cars they are one of the more likely things when worn to cause noises on bumpy roads.
Would you agree this is a good place to start? Are there any weak points that you know of on 5-series suspension that may be the cause of the noise?
The car passed its MOT only a few hundred miles ago and the noise was there then but has got a bit worse now.
Any advice you can pass on would be much appreciated. I have checked underneath the car for loose trim, heat shields and exhaust, etc., all being secure and they all seem OK. Ian Turner
A
I would totally agree with your diagnosis and before I reached the later part of your email – the anti-roll bar inner bushes were where I was going to suggest you looked. The droplinks are prone to wear and do produce a loud clunk when worn even slightly, but the inner bushes should as you say be a snug fit, and when worn do produce a slightly insulated thud, as the noise is metal hitting hard rubber as opposed to metal on metal.
I would certainly agree with the procedure you intend to follow and would be confident that this should resolve the problem.