I was getting a vibration noise with rapid travel movements in Y and for a while I suspected a bearing was failing. After some investigation I noticed this problem, the Y Axis Carriage plate was flexing away from the bed plate.
I guess my plate being Aluminum it was amplifying the noise.
My fix was simple enough but I think this needs to be added to the main part Y-table-10.stl to ensure future problems.
This also effects the belt tracking as the more tension you apply to the best the more it deflects and the more the belt misaligned on the motor and idles pulleys.