What could be causing a 'knocking' from my Renault Scenic's front suspension?

I have a 2002 Renault Scenic 1.9 dCi 75,000 miles. Having had to change two sets of Michelin tyres, to Falken 205/50 R16 (ZIEX ZE914) due to distorted tread, I now seem to have acquired slightly noisy suspension, both back and front. The front is still slightly noisy and feels like something is knocking or loose, with a bad shudder when crossing full road-width grooves. I've had two garages check the front suspension but neither can find any faults. My best guess would be the front dampers but the garages say they're OK. My thought is the problem is a lack of compression control as opposed to rebound control.

Asked on 5 October 2013 by DW, Crawley

Answered by Honest John
A suspension rattle is often caused by a sleeve bush dropping out of one of the attachments for the anti-roll bar.
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