It makes the noise going in a straight line. It almost sounds like the big gear that is on the axle, inside the housing, missing teeth and catching after skipping over the missing teeth. I was going to tear down the rear axle again but someone else mentioned that it could be a gear in the transmission so I wanted to see if anyone else experienced this before so I know where to start. I have only replaced the rear axle and one of the rear hubs as that was bent also when it was flipped.