Knocking or Clunking Over Speed Bumps? Common Suspension Faults

What that knock usually is

A knocking or clunking noise over speed bumps is almost always something in the suspension that has worn and gone loose. The most common culprits are anti-roll bar drop links, worn bushes, ball joints, broken coil springs and worn shock absorbers or top mounts. Most are not expensive parts, but they do affect how the car handles and brakes, and several are MOT failure items.

The usual suspects

Drop links: short rods that connect the anti-roll bar to the suspension. When the joints wear they rattle or knock over uneven surfaces, especially at low speed. One of the most common causes of a clunk.

Coil springs: springs can snap, often at the bottom coil, and a broken spring is an MOT failure. It may cause a clunk, the car sitting lower on one corner, or a sharp bang when the break happens.

Bushes: rubber bushes locate the suspension arms. When they perish or split you may hear a knock or a creak and feel the car wander.

Ball joints: a worn ball joint can knock over bumps and make the steering feel loose. It needs replacing promptly, as a failure affects steering control.

Shock absorbers and top mounts: worn dampers make the car bounce and float after bumps, and a worn top mount can clunk as you turn the steering.

What about squeaking?

A creak or squeak over bumps, particularly in cold or dry weather, is often a dry or worn rubber bush. It is less urgent than a knock, but worth checking at your next service or MOT.

Why it matters

Worn suspension affects braking distances and how the car behaves in an emergency swerve, and it can wear your tyres unevenly. With speed bumps on so many residential roads around Northfield, Kings Norton and Selly Oak, suspension parts here take a lot of punishment.

What we do

We put the car up on the ramp and check each joint, bush, spring and damper for play and damage, then show you what we have found and give you a written quote. If only one part is worn, we will tell you that — we do not replace parts that do not need replacing. Call us on 0121 476 2287.