Brake noise

There’s a knocking noise from the front brakes on my Mercedesbenz W202 C-class in forwards and in reverse. I have fitted new discs and pads, but still have the noise. Graham Moore

I am assuming that the noise was there before replacing the brake discs and pads and has not changed as a result of the new parts. If this is the case, I would check that the noise is coming from the brakes and not one of the suspension components. A quick check for this would be to jack up the vehicle and get an assistant to depress the brake pedal while you turn the road wheel backwards and forwards. If you can recreate the noise, then the most likely problem is a loose brake pad. As the pads are new, this may suggest a worn carrier. A small application of brake grease on the contact surfaces of the brake pads may be sufficient to silence the noise.

If you cannot recreate the noise, the problem could be a worn swivel – either one of the top or lower swivels may have enough movement when braking to create the noise. A distorted backplate is another common source of brake noise and it takes only a tiny contact point to cause a loud sound.