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DIAGNOSIS AND TESTING GEAR NOISE Axle gear noise can be caused by insufficient lubri- Gear noise usually happens at a specific speed range. When road testing, first warm-up the axle fluid by driv- • Check for insufficient lubricant. • Incorrect ring gear backlash. • Gear damage. Differential side gears and pinions can be checked by turning the vehicle. They usually do not cause noise during BEARING NOISE The differential and pinion bearings can produce noise when worn or damaged. Bearing noise can be either a whin- Pinion bearings have a constant-pitch noise. This noise changes only with vehicle speed. Pinion bearing noise will Worn or damaged differential bearings usually produce a low pitch noise. Differential bearing noise is similar to Wheel hub bearings produce noise and vibration when worn or damaged. The noise generally changes when the LOW SPEED KNOCK Low speed knock is generally caused by a worn U-joint or by worn side-gear thrust washers. A worn pinion shaft VIBRATION Vibration at the rear of the vehicle is usually caused by a: • Damaged propeller shaft. • Missing propeller shaft balance weight(s). • Worn or out-of-balance wheels. • Loose wheel lug nuts. • Worn U-joints or CV joints. • Loose/broken springs. • Damaged axle shaft bearing(s). • Loose pinion gear nut. • Excessive pinion yoke run out. • Bent halfshaft(s). 3 - 248 REAR AXLE - 215RII LX |