Steering knuckle explained

0 votes
added in Auto system and parts by Beta

Delta, RSLab

Steering knuckles, also sometimes called uprights, are vital components in a vehicle's steering system. They play a critical role in connecting the suspension, steering, and wheels, allowing for controlled turning and proper wheel alignment. Here's a breakdown of their key functions and components:


  • Connects Suspension and Steering: The steering knuckle acts as a central connection point between the suspension components (control arms, struts) and the steering system (tie rods). This allows the steering input from the driver to be translated into movement of the wheels.
  • Supports Wheel Assembly: The steering knuckle provides a sturdy mounting point for the wheel hub and bearings, which in turn support the wheel and allow it to rotate freely.
  • Enables Steering: The steering knuckle has attachment points for the tie rod, which transmits the turning force from the steering gear (rack and pinion or steering box). The design of the knuckle allows the wheels to pivot left and right as the tie rod pulls or pushes on it.
  • Maintains Wheel Alignment: The steering knuckle plays a role in maintaining proper wheel alignment. The angles at which the knuckle is positioned relative to the suspension components and the wheels affect factors like camber (tilt) and toe (straightness) of the wheels.


  • Knuckle Body: The main body of the steering knuckle is a forged or cast metal component that provides strength and support.
  • Spindle or Hub Mounting Point: This is the area where the wheel hub and bearings are mounted, allowing the wheel to rotate.
  • Ball Joint Attachment Points: The steering knuckle typically has one or more ball joint attachment points for the control arms (upper and/or lower) from the suspension system. Ball joints allow for controlled movement while maintaining a strong connection.
  • Tie Rod Attachment Point: The knuckle has a designated point where the tie rod connects, enabling the transfer of steering force.


Steering knuckles are typically made from high-strength steel or forged aluminum for a balance of strength, rigidity, and weight efficiency. They need to be able to withstand the significant forces exerted during steering and suspension movements.


Steering knuckles are critical for safe vehicle operation. Worn or damaged steering knuckles can lead to:

  • Difficulty steering or loose steering feel
  • Uneven tire wear
  • Abnormal noises from the suspension
  • Vibrations in the steering wheel
  • In severe cases, misalignment or complete loss of steering control

Regular inspection and maintenance of the steering system, including the steering knuckles and their components (ball joints, tie rods), are crucial for ensuring safe and predictable vehicle handling.