A method and apparatus for measuring cluster gears for run-out employs a plurality of master gears, each engageable with one of the gears of the cluster and each supported on a fluid cylinder powered slide movable radially to a gear to be measured. As the gear to be measured is rotated, the radial motion of the slides is sensed and compared to maximum values by a computer. An additional master gear, having sections engageable with each gear of a cluster simultaneously on its own slide, may be provided to measure the total run-out of the cluster.