Knocking wiper blades

[ojiisan]

In order to stop this irritating noise, I have changed the blades to new Bosch ones. I have tried cleaning the screen thoroughly but they are still noisier than they should be or than they were several months ago. I drive a Toyota Avensis (51 Reg). Can anyone please advise.

[woodchopper]

If they are new wipers I would doubt that they are doing the knocking - possibly a worn joint in the wiper arm assembly or where it attaches to the pivot, a worn pivot itself or worn linkages - also make sure the end of the wiper blade isin't being bashed off the door pillar/bulkhead at the top and bottom of its movement.
If the blades judder accross the windscreen it is because they are not set correctly - to check this, lift the wiper off the windscreen and put it back again almost touching the screen - the blade should be at 90 degrees to the windscreen.
If it needs altering - get an adjustable spanner and close it on to the wiper arm close to where the wiper attaches and twist the arm round so that the blade is at 90 degrees to the screen.

[markja]

in addition to woodchoppers reply, make sure the metal/plastic blade holder is in the slot of the blade where it is meant to be, not between the correct slot and the blade itself. this will make it judder however you adjust it . check top and bottom slots/guides.