when at a stop light it cannot be the brakes. and yes the other mounts need to be replaced. that should solve the problem. when my first mount went it was like a chain reaction, they all started to go. even with one mount broke, it will still vibrate. and only when you are coming up to a stop light will the steering wheel shake and that is tellign you that your rotors are warped. hope that helps. so get those mounts fixed. the mounts work together to stop the vibration.