Inspection and Verification: Knock
WARNING: This page is about a different car, the 2006 Ford Pickup, 2006 Ford F550 Super Duty, 2006 Ford F450 Super Duty, and 2006 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
Knock, which can occur on all driving phases, has several causes including damaged teeth or gearset.
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.