Traction-Lok Differential

 WARNING: A VEHICLE EQUIPPED WITH A TRACTION-LOK 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 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 FLOOR.

 CAUTION: 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.

 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.

Tires

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. Also, they 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. The best tires should be on the rear to minimize vibration; especially on vehicles with rear coil springs.

Driveline Angle

An incorrect driveline (pinion) angle can often be detected by the driving condition when vibration occurs.

1. A vibration during coasting from 72 to 56 km/h (45 to 35 mph) is often caused by a high pinion angle.

2. A vibration during acceleration, again around 56 to 72 km/h (35 to 45 mph), may indicate a lower than specified pinion angle. Refer to Section 00-04 for pinion angle procedure.

   When it is certain that the tires and driveline angle are not the cause, inspect the axle and U-joints. Refer to Section 00-04.

Axle Shaft Runout

Runout of the axle shaft at either end is an infrequent, but possible cause of rear end vibration. It is advisable to check the axle shafts for runout of:

1. The pilot (radial)

2. The flange face (lateral)

3. The bolt circle (radial)

   Refer to Section 00-04, for the checking procedures and special service tool for axle shaft runout.

   NOTE: If the axle shaft assembly is removed, check runout of the shaft itself. The forged (unmachined) part of the shaft is allowed to have as much as 3.0mm (0.120 inch) runout. This will not cause a vibration condition by itself.

Circular Companion Flange Runout

Circular companion flange runout should be checked when all other checks have failed to show the cause of vibration.

Another cause of excessive companion flange runout is improper installation of the pinion seal. If the spring on the seal lip is dislodged, it will jam up and cock the flange. Check that possibility before replacing the gearset because of flange runout.