Abstract: A method for balancing turbochargers or other high speed rotating equipment in which relatively large masses require balancing in two axially separated planes includes the steps of mounting the mechanism to be balanced in a test fixture so that the mechanism can move in a substantially unrestrained manner in any of the three spatial dimensions. Accelerometers adjacent opposite ends of the rotating component measure maximum acceleration of the housing due to vibration. Since the housing substantially unrestrained, the measurement of vibration at any end of the device will be influenced by vibrations induced by the mass at the other end of the device, since the mechanism is not otherwise damped by supporting structures. An optical sensor measures phase angle, and this information along with the information generated by the accelerometers is fed to a conventional vibratory analysis device to determine the unbalance of the rotating component.