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GEAR NOISE Axle gear noise can be caused by insufficient lubri- cant, incorrect backlash, tooth contact, worn/damaged Gear noise usually happens at a specific speed range. The noise can also occur during a specific type When road testing, first warm-up the axle fluid by driving the vehicle at least 5 miles and then acceler- • Check for insufficient lubricant. • Incorrect ring gear backlash. • Gear damage. by turning the vehicle. They usually do not cause BEARING NOISE The axle shaft, differential and pinion bearings can all produce noise when worn or damaged. Bearing Pinion bearings have a constant–pitch noise. This noise changes only with vehicle speed. Pinion bearing Worn or damaged differential bearings usually pro- duce a low pitch noise. Differential bearing noise is Axle shaft bearings produce noise and vibration when worn or damaged. The noise generally changes LOW SPEED KNOCK Low speed knock is generally caused by a worn U–joint or by worn side–gear thrust washers. A worn VIBRATION Vibration at the rear of the vehicle is usually caused by a: • Damaged drive shaft. • Missing drive shaft balance weight(s). • Worn or out–of–balance wheels. • Loose wheel lug nuts. • Worn U–joint(s). • Loose/broken springs. • Damaged axle shaft bearing(s). • Loose pinion gear nut. • Excessive pinion yoke run out. • Bent axle shaft(s). or engine/transmission mounts. These components All driveline components should be examined before starting any repair. Refer to Group 22, Wheels and Tires, for additional vibration information. DRIVELINE SNAP A snap or clunk noise when the vehicle is shifted into gear (or the clutch engaged), can be caused by: • High engine idle speed. • Transmission shift operation. • Loose engine/transmission/transfer case mounts. • Worn U–joints. • Loose spring mounts. • Loose pinion gear nut and yoke. • Excessive ring gear backlash. • Excessive side gear to case clearance. mined with the assistance of a helper. Raise the vehi- TRAC–LOK Y DIFFERENTIAL NOISE The most common problem is a chatter noise when turning corners. Before removing a Trac-lok y unit for repair, drain, flush and refill the axle with the A container of Mopar t Trac-loky Lubricant (fric- tion modifier) should be added after repair service or After changing the lubricant, drive the vehicle and make 10 to 12 slow, figure-eight turns. This maneu- 3 - 70 194 RBI AXLE XJ DIAGNOSIS AND TESTING (Continued) |