A big thank you to Joe Spddracer for helping me diagnose and fix this annoying problem... he emailed me saying the noise comes from the axle creaking on the bearing face on the inside... to fix just move the axle in slightly and spray some White lithium in behind the axle and bearing. The hardest part would have been to remove the axle nut (36mm), but I used ZonaZs impact wrench which made it easy. After it was greased up and torqued back to spec... the clicking was history :)