What Is a Wishbone / Control Arm?
The wishbone — also called a control arm — is a triangular or A-shaped suspension component that connects the wheel hub to the vehicle subframe at two pivot points. The outer end connects to the hub via a ball joint; the inner end connects to the subframe via rubber or polyurethane bushes. On multi-link suspension systems, several arms work together to control every aspect of wheel movement — camber, toe and caster — as the suspension compresses and extends.
What Does the Wishbone / Control Arm Do?
The wishbone geometry precisely controls how the wheel moves relative to the vehicle body as the suspension travels. Correct wheel alignment is maintained through the designed geometry of the wishbone and its attachment points. Worn bushes or a bent arm (from kerb strikes or pothole damage) compromise this geometry, causing tyre wear, handling instability and potential pull to one side under braking.
Fault with your wishbone / control arm?
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Get My Free Fault Scan →Symptoms of a Failing Wishbone / Control Arm
Worn wishbone bushes cause a clunking or knocking noise, particularly under braking or on rough surfaces. The steering may feel vague and the vehicle may wander at motorway speeds. Abnormal tyre wear on the inside or outside edges is a common consequence. A bent wishbone (visible on inspection) causes pulling and handling instability that cannot be corrected by wheel alignment adjustment alone.
When Should the Wishbone / Control Arm Be Replaced?
Wishbone bushes are replaced on wear — typically every 60,000 to 100,000 miles on high-mileage vehicles. Bush replacement requires pressing the old bushes out and new ones in — often requiring a workshop press. Complete wishbone assemblies (including new bushes and ball joint) are sometimes more cost-effective than bush replacement alone.
If you are experiencing symptoms related to your wishbone / control arm and are unsure whether it needs replacing, a free MotorLoom fault scan can help identify whether the component is likely at fault - giving you the most likely cause and estimated repair cost before you visit a garage.
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Related Parts
Other components that work alongside or are related to the wishbone / control arm: