Knocking noise under car after bottoming out on driveway
Impact to the underside of a vehicle can bend or loosen protective shields, exhaust hangers, or suspension components like the CV axle and control arms. This creates persistent rattling over bumps and when braking, even if the car otherwise drives normally.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
- 1Checking components like swaybar end links, worn strut/shocks, inner tie rods, and link pins
- 2Using a metal pipe under the control arm to lift and simulate going over a bump to locate the sound
- 3Replacing suspension components like sway bar links
- 4Having mechanics inspect the vehicle
- 5Considering returning the vehicle's suspension closer to stock configuration
- 6continuing to drive
- 7inspecting for damage
In their words
Unedited, most upvoted first, each linked to the thread it came from.
“Been hearing knocking like the sound in the video when driving over bumps so I removed the wheel to investigate and this is what I found. Would you say that the CV axle needs to be replaced?”source ↗
“I backed my car up on an unfinished driveway and slammed my car on the ground and every since it does this knocking It drives 100% fine. It’s just a rattling sometimes it happens when I break I speed it’ll happen for almost anything.”source ↗
“Noise goes away when I accelerate or im at higher speed.”source ↗
“Does anyone know what this sound is? It only happens when I'm entering or exiting a ramp. I already replaced the sway bar links, but the noise is still there.”source ↗
“It's even been checked by mechanics and they still can't figure out where it's coming from—plus, all of this started right after I installed coilovers.”source ↗
“Also, it's been getting worse lately and happening more frequently.”source ↗
Where this came up
People with this problem also raised
- 7Why does the strut top mounting plate rotate by hand?
- 16Why are my brakes squeaking and shaking the floorboard?
- 3How to tell if a front end shake is tie rods or wheel bearings
- 48How to explain an intermittent car noise to a mechanic
- 26Why does my car make a loud rattle when starting the engine?
- 2Why is my car suspension popping after replacing struts and springs?