The Dynamics of Automotive Rear Axle Gear Noise

Automotive rear axle gear noise is characterized by a tonal peak of several mph bandwidth, usually in the 40-70 mph speed range.

A study of the mass-elastic system of rear axle gears predicts the existence of a nearly vertical resonance of the pinion, relative to its supports near the frequency of the observed noise peak.

Experimental studies of a variety of rear axles confirm the existence of this vibration peak and its coincidence with the observed noise.

The magnitude of the various orders of gear meshing quality resultant from eccentricities, wobble, heat-treatment distortion and higher harmonics can be assessed by monitoring the amplitude of this resonance at specified gear meshing frequencies.