Suspension knocking over bumps: causes and what to do

Knocking, squeaking or dull thuds from underneath over potholes, speed bumps and cobblestones. Often the cause is worn rubber and ball-jointed parts, less often the shock absorbers or steering. You can’t pinpoint the part by ear alone — it takes an inspection on a lift with a check for play.

How it shows up

• Light, dry knocking over small bumps and cobblestones
• A dull thud on a big pothole or over a speed bump
• Squeaking when the body rocks, over speed bumps or in freezing weather
• Knocking or clicking when turning the steering wheel at a standstill or while parking
• The car keeps bouncing after a bump or feels floaty at speed
• Uneven tyre wear, the car pulls to one side

Possible causes

1. 01

   Stabiliser links

   A typical cause of light knocking over bumps, especially when one wheel hits an obstacle. The part is inexpensive, but its noise is easy to confuse with more serious faults.

2. 02

   Control arm and stabiliser bushings

   Rubber bushings crack and separate over time. This causes dull thuds, squeaks and vague handling; stabiliser bushings often squeak in the cold.

3. 03

   Ball joints

   A worn ball joint knocks over bumps and gives the wheel play. It is a safety-critical part: with heavy wear the joint can separate, so don’t put it off.

4. 04

   Shock absorbers and strut mounts

   A leaking or worn-out shock absorber gives hard bottoming-out thuds and bouncing. A worn top strut mount knocks and creaks from above, often noticeable when turning the wheel.

5. 05

   Tie rods and tie rod ends

   Play in a tie rod end or inner tie rod causes a knock felt through the steering wheel and imprecise steering. If the noise comes from the steering rack itself, that’s a separate fault, which we check along with the suspension.

6. 06

   Dust boots, bump stops, springs

   A destroyed bump stop or shock boot causes thuds on big potholes. A cracked or sagging coil spring can knock and lower ride height on one side.

How we check

1. 01We ask exactly when it knocks: over which bumps, at what speed, when turning the wheel
2. 02If needed, we take a short test drive to hear the noise
3. 03On a lift we check joints for play and inspect bushings, boots and shock absorbers
4. 04We explain what’s worn and agree on the repair and its cost before starting work