Knock

Knock, which can occur in 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. Occasionally, the rear axle differential gear case bolts will knock against the inside of the rear axle housing casting. The cause may be too little clearance due to casting flash bumps or simply the bolts may be loose. In this case, the differential case can be removed and the interference points ground out.

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

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