
334 LIGHT AND HEAVY VEHICLE TECHNOLOGY
20.6 REAR AXLE MISBEHAVIOUR IN SERVICE
Final drive noise
Noisy operation is the most likely type of complaint to
arise in a final drive unit, as a result of either defective
build or long-term wear. It is fairly readily distinguish-
able to the vehicle occupants, because its frequency is
usually much higher than the other potential sources of
noise in a motor vehicle. Before attempting to diagnose
any such complaint of noise, the final drive must be not
only checked for correct oil level, but also allowed to
attain a normal running temperature before testing
proper begins. Furthermore, the possibility o ...