I need some help on my 318i cabrio. Horrible shaking on bad road surfaces. Replaced front control arm bushes which made no difference. Checked rear shock mountings and have a question. When leaning on the back of the vehicle there is about 5mm play between the washer below the lock nut and the shock mounting (in the boot). This does not seem right I dont think there should be play on a shock mounting. Could this be the cause or is this play normal?