Just thought I would let you know that I have recently sorted out a knocking that my W reg A140 had developed. The knock was mainly heard when going over pot holes/drain covers or around sharp bends. On jacking up the rear of the car I detected about 4 mm play when pulling/pushing on each wheel which led me to think that the bushes/bearings at the front of the trailing arm were shot. A visit to my local Merc dealer showed that the arms are fitted with a taper roller bearing set up which they insisted was a case of fitting replacement complete trailing arms.However, bearing repair kits were shown on their parts computer and I have now fitted same and all knocking noises have ceased. The good bit- they wanted £480+vat and 4 hours to do the job.I did it for £48 total and 6 hours graft. On asking them about why a just over 3 year old car/30k mileage, had developed such a fault I was told it was "unusual".Makes you wonder just how many A Class cars have had such a problem!
tony