Ok so my 07 lbz has been makin a loud hummin noise, I'm not positive its the transmissions but the noise gets louder as I shift gears an then it cuts out when I go in 5th an 6th. I've checked for codes an there aren't any. I have changed the transmission fluid since bought it used 30,000 miles ago. It has 132000 now. It seems to always make the noise after the transmission gets over 180. I don't know what to do.