knocking at rear

hi i have a 51 plate td5 auto with 112000 on the clock. it makes fairly loud knocks at the rear when you go over bumps or speed humps. also if you go around a small roundabout there is a bump you can hear and feel at the rear .dont seem to do it on large roundabouts. i changed the offside rear tie bar bushes .it failed the mot on this about a month ago. i have just replaced the watts linkage bushes the 2 either side of the center bush were really knackered. my mate who is a mechanic had a look underneath and said the shock absorber bushes seem ok but we would perhaps change them next and hope that cures it. any one any ideas? many thanks

did you change all 5 watts linkage bushes? Also, although you changed the anti roll bar drop links, it would be worth sliding under and having a good tug in them again, its not unknown for new ones to becone loose quickly.

+1 for one of the anti roll bar links

Same thing happened to mine and it was the shock absorber. I know your mechanic said it isn't but just take another look.

Mine made a very loud bang when going over any sort of bump. If you have someone rock the car up and down by jumping on the rear step and look at your shock absorbers you will probably see them catching something which is causing the noise.