I have a noise that sounds like a old caliper brake as well, but only during take-off and it goes away. Mine points to a out of adjustment front (or rear) disc brake. Very hard to pinpoint. The Mini is new with only 1 mile so far. I was going to check/adjust everything anyways. Now I know my RadRunner motor makes a funny noise during take-off to mid-range but its a normal noise. Trying to think of what to compare it to. Runner has around 2000 miles. Hope this helps?