A creak that appears exactly as you cross a bump and fades on smooth tarmac is the most widespread interior sound. It rarely means a breakdown, yet it almost always irritates more than real faults: you hear it on every town journey, and it is impossible to place by ear. Here is why a bump triggers the creak, how to separate the interior from the running gear in a single drive, and what to do with the source once found.
Why the sound appears on a bump
A car body flexes elastically. When one wheel goes through a pothole, a door aperture briefly loses its right angles, the body pillars move slightly apart and the floor twists diagonally. Everything mounted inside follows the body, but at different rates — and at the joints microscopic slipping occurs. While a factory seal separates the parts, that movement is silent; once a strip has dried out or a clip has loosened, plastic slides on plastic dry and creaks.
Hence a practical conclusion: the loudness of the creak depends not on how hard the car was shaken but on how asymmetrically. A smooth undulation on a motorway can pass silently, while putting one wheel onto a kerb produces a whole concert.
Interior or suspension
| Sign | Interior | Suspension |
|---|---|---|
| Timbre | Dry, high, plastic | Lower, duller, often metallic |
| Reaction to pressing the trim | Stops or changes | Unchanged |
| Rocking the parked car | Usually silent | The creak reproduces |
| Felt through the wheel and pedals | No | Often yes |
| Window open | Heard from inside | Heard from outside |
The fastest check is rocking. Park the car, push down with your whole weight on each wing in turn and release. If the creak reproduces with no movement of the body relative to the interior, look underneath: dry bushes, a strut mount, anti-roll bar bushes. That catalogue is on the symptom page knocking in the suspension, with the creak version in suspension creaking over bumps.
The second check is an open window while crossing a speed hump slowly. An interior creak becomes quieter (the sound leaves the enclosed space); a suspension creak becomes clearer.
What to look for inside and how to fix it
Start with the obvious: an empty glovebox, cubbies, boot. Then four zones account for most cases. The joint between the dashboard and the windscreen and A-pillars is cured with a felt strip worked into the seam. Door trim panels — by replacing loose clips. Seat runners and adjustment mechanisms — with a smear of grease. The parcel shelf and its supports — with a piece of foam in the seat. Dashboard rattles are their own topic, covered in a rattling dashboard.
The general rule is the same as for any dry contact: the parts need separating with a soft material, not clamping harder. Tightening usually moves the creak to the neighbouring joint and the search starts again.
When to go to a workshop
A visit makes sense in two cases: the creak appeared abruptly after a pothole strike, or a knock, vibration or a change in steering behaviour has joined it. On a lift the suspects are the usual ones — anti-roll bar bushes, control arm bushes, strut top mount bearings, and the underbody fasteners; their signs are in signs of worn anti-roll bar bushes.
If the check shows the suspension is not involved, the remaining creak is cosmetic and can be dealt with without hurry, even at the weekend. It is worth preparing before winter, though: in frost the list of creaking places usually grows — see interior creaks in winter.
The most reliable way to stop arguing with yourself about where the sound comes from is to record it. Start a recording in the Pro-Stuk app before a familiar rough stretch and drive it twice: with the windows closed and open. The app matches the recordings with your answers and shows where to look — inside the cabin or under the car.
