Topic:
Steering Knuckle:
The steering knuckle (also known as knuckle or knuckle body) plays an important role in the wheel suspension. It acts as a pivot point for the ball joint (at the bottom of the knuckle) and the tie rod end. The shock absorber is clamped at the top of the knuckle, allowing it to turn with steering movements. The wheel bearing is also mounted in the knuckle. The image shows part of the wheel suspension with the wheel bearing mounted with 4 bolts, but a wheel bearing can also be pressed into the knuckle. In this case, no bolts are present and special pressing tools are required for assembly or disassembly.
The image is of a steering knuckle from the front axle of a VW Golf (Mk 6).
Ball Joint:
The knuckle in the image is now viewed from the opposite side (the inside). The ball joint is mounted at the bottom. This is the connection between the lower control arm of the chassis (where the triangular plate with nuts is attached) and the knuckle itself. When steering, the tie rod pushes or pulls the knuckle around its axis. It hinges on the ball joint and rotates with the shock absorber. Defects in the ball joint may occur due to a torn dust cover, driving (hard) over speed bumps or road bumps, or extreme loads on the wheel suspension (e.g., by driving over curbs).
