Clunk Diagnosis

Clunk is due to backlash in the driveline, but not necessarily in the axle. To determine whether driveline clunk is caused by the axle, make a check of the total axle backlash as follows:

1. Raise vehicle on a frame or twin hoist so that rear wheels are free.

2. Clamp a bar between axle companion flange and a part of the frame or body so that flange cannot move.

3. Lock left rear wheel to keep it from turning.

4. Using a torque wrench located on a wheel nut, rotate the right wheel slowly until reaching a torque of 6-8 Nm (5-6 lb-ft). Hold a chalk marker against one side of tire 304.8mm (12 inches) from center of wheel.

5. Rotate wheel slowly in the opposite direction until reaching a torque of 6-8 Nm (5-6 lb-ft).

6. Measure length of the chalk mark, which is the total axle backlash. It should be 25.4mm (1 inch) or less. If the backlash is within this limit, check the following items:
   • Engine mounts
   • Transmission mounts
   • Universal joints
   • Slip yoke
   • Loose companion flange bolts
   
   
   
   
   

   Check for the following conditions if backlash is excessive:

7. Elongation of the differential pinion shaft holes in the differential case.

8. Missing differential or side gear washer.

9. Galling of the differential pinion shaft and bore.

   If none of the above conditions show up, there may be a loose fit of the axle shafts to the side gear splines. Continue as follows until the correction is made.

10. Install new side gears and check the backlash.

11. Install two new axle shafts.

12. Replace the axle assembly.