grinding

I have a 2000 explorer. I noticed the passenger front wheel was knocking slightly when turning in that direction while either moving or at a stand still. The knocking has subsided.(kinda scary)... I replaced the front brake pads and tried to clean any remaining fluid off of the discs. Since the front brakes have been replaced I have noticed a rolling grinding noise(not a friction grind) when I have driven the vehicle a reasonible distance.(does not occur when the car is first driven) Thinking it was a wheel bearing, I took it in to have a diagnostic done. The wheel bearings were fine. I had the front end re-aligned and had the rear brakes replaced. I've noticed the grinding happens when turning the wheel and slowing, at the same time. Sometimes the grind is loud, sometimes quiet. Any suggestions would be helpful. Thanks.