Thumping noise front

[SteveC]

I have a loud thumping noise from the front of my 2001 Discovery. I just replaced the brake calipers, pads and rotors on all four tires. During test drives for bleeding the brake lines everything seemed fine. Within the first 20 miles or so after considering the job done a loud thumping started. It is coming from the front, it seems like the driver's side. It is rhythmic and changes to match speed. I shifted to neutral while underway and the symptoms did not change. The vehicle sat in the garage for a few months while I was working on the brakes but the thumping is louder\stronger than a flat spot on a tire would cause. What should I check?