Symptoms
- Clunk or knock sound specifically when going over bumps or dips
- Silent on smooth roads
- May be felt as a jolt in the steering wheel or seat in addition to heard
- Could come from the front or rear, one side or both
Likely causes
- CommonWorn sway bar end linksThese small linkages commonly wear and develop play, creating a clunk over bumps, especially at the front.
- CommonWorn or failing strut mountsA worn mount at the top of the strut allows extra movement and can clunk over bumps.
- CommonWorn suspension bushings (control arm, sway bar)Bushings that have hardened, cracked, or separated allow excess movement.
- PossibleLoose or worn ball jointA ball joint with excess play can clunk over bumps and is a safety-relevant component.
- PossibleLoose shock absorber or strut mounting hardwareHardware that's backed off slightly can allow enough movement to clunk.
What to do
- Note whether the clunk seems to come from the front or rear, and from one side or seemingly both.
- Check the trunk and cargo area for loose items that might be shifting, since this is an easy thing to rule out first.
- Have a mechanic put the car on a lift and use a pry bar to check for play in sway bar end links, ball joints, and bushings, which is far more reliable than a visual check alone.
- Have strut mounts checked, since these can be a common source of a bump-related clunk, especially on higher-mileage vehicles.
- Avoid ignoring a suspension clunk, since some of the components involved (ball joints, in particular) relate directly to steering and handling safety.
- Get any worn ball joint replaced promptly, since a joint that fails completely while driving can cause loss of control.
- Replace sway bar end links and worn bushings as diagnosed, which are generally moderate-cost repairs.
- Have the full suspension inspected at the same time, since worn components often aren't isolated to just one part.
Tools and parts
- Flashlight
Sway bar end linkSearch: “sway bar end link for [year make model]”
Strut mountSearch: “strut mount for [year make model]”
When to call a pro
A clunk over bumps should be diagnosed by a mechanic on a lift with a pry-bar check, since worn ball joints and other suspension play aren't always obvious from a visual inspection alone, and some of these components are safety-critical.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.