Rotors and bearings don't make knocking sounds. Bushings could depending on which ones. Common causes are worn ball joints, tie rod ends, struts, upper strut mounts, and anti-sway bar links and bushings. It's helpful to know when and under which conditions the noise occurs. Your best bet is a suspension and steering inspection at a tire and alignment shop. That is normally a part of any alignment.
Monday, June 27th, 2011 AT 8:52 PM