Knock

Knock, which can occur on all driving phases, has several causes. In most cases, the technician will discover one of the following conditions:
1. A gear tooth damaged on the drive side is a common cause of the knock. This can usually be corrected by grinding the damaged area.





2. Knock is also characteristic of excessive end play in the axle shafts. Up to 0.762 mm (0.030 inch) is allowed in most axles. The frequency of knock will be less because the axle shaft speed is slower than the driveshaft.

NOTE: Be sure to measure the end play with a dial indicator and not by feel.