Knock

Knock, which can occur on all driving phases, has several causes including damaged teeth or gearset.

In most cases, one of the following conditions will occur:





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 or bumps. In this case, the differential case can be removed and the interference points ground out.

Another possibility is simply that one or more rear axle differential gear case bolts are slightly backed-out. Remove, replace and properly tighten the rear axle differential gear case bolts using Stud and Bearing Mount EOAZ-19554-BA or equivalent meeting Ford specification WSK-M2G349-A1 on the threads.

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.

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