Axle Backlash Check

Clunk noise is due to backlash in the driveline, but not necessarily in the rear axle. To determine whether driveline clunk is caused by the rear axle, make a check of the total axle backlash as follows:
1. Raise the vehicle on a frame or twin-post hoist so that the rear wheels are free.

NOTE: Do not perform this procedure for limited slip axles. There is no effective way to check backlash on limited slip axles.





2. Clamp a bar between the rear axle companion flange and a part of the frame or body so that the rear axle companion flange cannot move.
3. Lock the left rear wheel to keep it from turning.





4. Turn the right wheel slowly until you "feel" it in a drive condition. Hold a chalk marker on the side of the tire 304.8 mm (12 inches) from the center of the wheel.
5. Turn the wheel the other way until you again feel the drive condition.
6. Measure the length of the chalk mark, which is the total axle backlash. It should be 25.4 mm (1 inch) or less.

If the backlash is within this limit, the clunk will not be eliminated by going into the axle.

7. Check for these conditions if the backlash is excessive:
^ Elongation of the differential pinion shaft holes in the differential case.
^ Missing differential pinion thrust washer or differential side gear thrust washer.
^ 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. You should continue as follows until the correction is made.
^ Install new differential side gear and recheck the backlash.
^ Install two new axle shafts.