A diagnostic vibration analyzing system 10 and method for measuring and characterizing the torsional vibrations in a vehicle or a piece of industrial equipment collectively a "vehicle". An electronic control unit 22 and sensor 12 cooperate to measure speed fluctuations occurring between the passing of adjacent teeth of a rotating gear. These time measurements 18 are the basis for displacement, velocity and acceleration calculations which, combined with driveshaft rotational order information, can be used to pinpoint the source of excessive driveline torsional vibrations. The use of multiple sensors 12 can maximize per test the information available for analysis. The use of multiple sensors 12 in a substantially simultaneous manner can isolate particular components in the tested vehicle.
