Vibrations

Few vibration conditions are caused by the rear axle. Follow the diagnosis procedure for vibrations concerns unless there is a good reason to suspect the rear axle or drive shaft.

Most vibration in the rear end is caused by tires or driveline angle.

TRACTION-LOK DIFFERENTIAL

WARNING: NEVER RUN ENGINE WITH ONE WHEEL OFF THE GROUND. A VEHICLE EQUIPPED WITH A TRACTION-LOK ID DIFFERENTIAL WILL ALWAYS HAVE BOTH WHEELS DRIVING. IF, WHILE THE VEHICLE IS BEING SERVICED, ONLY ONE WHEEL IS RAISED OFF THE FLOOR AND THE REAR AXLE SHAFT IS DRIVEN BY THE ENGINE, THE WHEEL ON THE FLOOR COULD DRIVE THE VEHICLE OFF THE STAND OR JACK. BE SURE BOTH REAR WHEELS ARE OFF THE GROUND.

TIRES

WARNING: DO NOT BALANCE THE REAR WHEELS AND TIRES WHILE THEY ARE MOUNTED ON THE VEHICLE. POSSIBLE TIRE DISINTEGRATION AND/OR DIFFERENTIAL FAILURE COULD RESULT, CAUSING PERSONAL INJURY AND/OR EXTENSIVE COMPONENT DAMAGE. USE OFF-VEHICLE WHEEL AND TIRE BALANCER ONLY.

NOTE: Some vehicles are equipped with directional tires (see tire rotation arrows on tire sidewall). If a directional tire is removed for service, it must be remounted in its original location.

Vibration is a definite concern with modern, high-mileage tires if they are not true both radially and laterally, They are more susceptible to vibration around the limits of radial and lateral runout of the tire and wheel assembly. They also require more accurate balancing. Wheel and tire runout checks, truing and balancing are normally done before axle inspection.

Sometimes a vibration concern can be corrected by properly rotating or inflating the tires.

U-Joint wear vibration can be caused by worn or binding universal joints.

U-JOINT WEAR
Vibration can be caused by worn or binding universal joints.

AXLE SHAFT RUNOUT

Special Tool:

Runout of the axle shaft is an infrequent but possible, cause of rear end vibration. Check the axle shaft for runout of the following surfaces as shown in the illustrations:

DRIVE PINION STEM AND REAR UNIVERSAL JOINT FLANGE
Rear axle universal joint flange runout should be checked as a potential cause of vibration.

A cause of excessive rear axle universal joint flange runout is improper installation of the pinion seal. If the spring on the rear axle drive pinion seal is dislodged, it will jam up and cock the rear axle universal joint flange. Check that possibility before replacing the gear set because of rear axle universal joint flange runout.