What are Wishbones / Control Arms?

In plain English

The control arm — often called a wishbone because of its A- or V-shape — is a hinged suspension link that connects the wheel hub to the car’s chassis (subframe). There is typically one or two per wheel: an upper and a lower arm on double wishbone setups, or a single lower arm on MacPherson strut systems. They are usually made of pressed steel or cast aluminium and have rubber bushings at the pivot points to allow controlled movement while absorbing road noise.

How it works

The control arm works like a lever. When the wheel moves up over a bump, the arm pivots around its bushings, keeping the wheel in the correct geometry while allowing vertical travel. The bushings dampen vibrations and maintain alignment. Drop links (on the anti-roll bar) connect through the arm to transfer stabiliser forces. On some designs, the arm also carries the lower mount for the shock absorber or spring. Everything is held together with ball joints at the outer end so the wheel can still steer while the suspension moves up and down.

Signs of trouble

• ⚠Knocking or clunking noise when driving over bumps or potholes
• ⚠Uneven or premature tyre wear, especially on the inner or outer edges
• ⚠The car pulling to one side under braking
• ⚠Vague or wandering steering feel at motorway speeds
• ⚠Visible play or movement in the wheel when jacked up and rocked (known as the 3-9 or 12-6 o’clock test)
• ⚠Bushings look cracked, perished or oil-soaked during a visual inspection