A single thump or thunk over bumps at low speed is almost always a worn suspension component. The slower the speed, the more isolated the noise, so failing parts stand out. The usual suspects: worn strut mounts, dead sway bar end links, blown control arm bushings, or a broken coil spring.
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A torn strut top mount lets the strut shaft shift inside the bearing and thump on every bump. Often paired with a slight clunk when turning. Parts: $35 - $120 each. Labor: $150 - $300. Difficulty: Medium DIY / Shop. Severity: Medium.
Get a Free AI Diagnosis →The cheapest, easiest cause. End links connect the sway bar to the strut. When the rubber bushing fails, the link slaps on every bump. Parts: $20 - $60. Labor: $50 - $120. Difficulty: Easy DIY. Severity: Low.
Get a Free AI Diagnosis →A failed front lower control arm bushing thumps when the suspension cycles. Often visible: rubber is cracked or oozing. Parts: $30 - $200. Labor: $150 - $400. Difficulty: Medium DIY / Shop. Severity: Medium.
Get a Free AI Diagnosis →The rubber bushings that hold the sway bar to the frame dry out and let the bar shift sideways, thumping over bumps. Parts: $10 - $40. Labor: $30 - $120. Difficulty: Easy DIY. Severity: Low.
Get a Free AI Diagnosis →A snapped coil spring (often at the tip) makes a dull thunk over bumps and can sag one corner of the car. Inspect visually. Parts: $80 - $250. Labor: $150 - $400. Difficulty: Shop. Severity: Medium.
Get a Free AI Diagnosis →On older cars, strut-tower bolts can loosen and the strut thumps in its mount. Free to torque back. Parts: $0. Labor: $0 - $80. Difficulty: Easy DIY. Severity: Low.
Get a Free AI Diagnosis →A loose tie rod or rack mount can thunk when the wheel deflects over a bump. Often paired with vague steering. Parts: $50 - $300. Labor: $150 - $400. Difficulty: Shop. Severity: Medium.
Get a Free AI Diagnosis →Use this quick-reference table to narrow down the cause based on exactly when you hear the noise.
| When You Hear It | Most Likely Cause |
|---|---|
| Thump on every small bump at low speed | Strut mount or end link |
| Loud clunk only over big bumps | Control arm bushing or broken spring |
| Thump + clunk turning the steering wheel | Strut top mount |
| Thump only on rough pavement, never on smooth | Sway bar bushings |
| One corner of car sits lower | Broken coil spring |
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Usually yes for short distances, but a broken spring or loose tie rod is a safety issue. Get it inspected within a week.
At low speed each bump is isolated. At highway speeds bumps blend together and the suspension stays loaded, masking the noise.
Yes, but more often it is the strut mount, not the strut itself, that thumps. A blown strut bounces.
About $80 - $200 per side, parts and labor. The easiest, cheapest suspension fix.
No. Alignment is about angles, not loose parts. You need to find and replace the worn component.
In many states yes, if the inspector finds a torn bushing or broken spring. Cheap parts to fix and pass.