I found this interesting.. in my case i considered it more of a chuff chuff chuff.. sound.. slower at slower speeds, speeds up as I do.. stays at a constant volume.. almost as if i had something in just one spot that rubs.. drives me insane.. I have had all 4 corners apart several times trying to figure out what the hell the noise is.. had the drums cut.. on and on.. still no idea.. if this 'woo woo woo' you speak of is the same thing I have going on, do you have any insight as to what it is and how I might make it stop?? lol