thumping noise when coasting
 

I hear a thumping sound when my car is coasting. When I apply the brakes the noise tends to stop. Under acceleration the noise is faint. But coasting it is very present. I have an hour drive ahead of me and am worried about this noise. what can i look for?

i have a 2002 wrx. I just replaced my rear brake pads.

Does your steering wheel vibrate when the brakes are applied? Sounds like something is up with the rotors. Sometime when the rotors are really bad they make a knocking sound. Which is actually the pads getting kicked around within the caliper if the rotor is not straight.

thanks foolio.