Clunking noise over bumps: what is worn

What it means

Every pivot in the suspension has a bushing, usually rubber or polyurethane, that cushions the joint, absorbs vibration and allows slight controlled movement without metal on metal contact. Ball joints let the control arm pivot in more than one direction, so the wheel can steer and travel at the same time.

Bushings degrade gradually with age, heat and road exposure. Once they wear, the result is a clunk or knock over bumps, a looser feel, and sometimes uneven tire wear.

Common causes

• Worn bushings, one of the most common causes
• Worn sway bar links
• A loose component
• A worn ball joint, especially if it also clunks when turning
• On an electric car, extra weight wearing these parts sooner than the mileage suggests

What to do now

1. Note exactly when it happens: over bumps or on smooth roads, turning or straight, and whether it changes with speed.
2. Notice whether the steering also feels looser or less precise.
3. Look at the tires for uneven or unusual wear.
4. Check for visibly torn rubber boots on the steering or suspension parts you can see.
5. If it clunks when turning and the steering feels loose, have it inspected right away.

Over bumps, or when turning?

• A clunk or knock over bumps, especially at low speed: often worn bushings or sway bar links
• A clunk when turning, with looseness or wandering: possibly a ball joint, so get it inspected right away
• A hum or growl that changes with speed: a wearing wheel bearing, not a clunk
• Manual car, a clunk on take-up or when lifting off: possibly a tired dual-mass flywheel
• Electric car, a clunk over bumps at five years old: not unusual, because the extra weight wears these parts sooner

What people often get wrong

That a clunk can wait because the car still drives fine. Worn bushings and links tend to get worse, not better, and can affect alignment over time. Some wear is expected with age, but a new or worsening noise is still worth checking.

When the car must go to a workshop

Ball joint, control arm and bushing replacement all belong with a professional, and a suspected ball joint should not wait: a failure while driving can cause a sudden loss of steering control. Ask for an alignment check after any suspension work.

Read next

• Car making a clicking noise: what the sound tells you
• Humming noise that rises with speed: wheel bearing?
• Car pulls to one side: how to find the cause

This page is general information and does not replace a professional assessment. Symbols, codes and behaviour vary between makes. Always check the handbook for your own car.