Why does it feel like scraping the chassis when braking?
4 Answers
The reasons for feeling like scraping the chassis when braking include: worn brake pads, loose chassis components, aging rubber parts of the chassis, lower arm failure, etc. Car owners can eliminate such abnormal noise by replacing brake pads, tightening chassis screws, or replacing rubber parts. Braking refers to the action of stopping or reducing the speed of running locomotives, vehicles, other means of transport, or machinery. The chassis refers to the combination of the transmission system, running gear, steering system, and braking system on a car, which supports and installs the car engine and its various components and assemblies, forming the overall shape of the car, bearing the engine power, and ensuring normal driving.
Last time I hit the brakes hard, I also encountered a similar situation, like the sound of the chassis scraping against a stone. Later, after checking, I found out there are mainly two reasons: one is small stones getting stuck between the brake disc and brake pads, especially after driving on gravel roads in the rain; the other is aging brake components, such as the spring clips holding the brake pads coming loose. I remember that time I got out to check if there were any stones stuck in the tire grooves, and when I took it to the repair shop and put it on the lift, it turned out the brake pad retaining clip on the left rear wheel had broken. The mechanic said if you encounter this situation, don't push your luck—addressing it promptly can both eliminate the noise and prevent damage to the brake disc.
Having repaired cars for over a decade, I've encountered numerous similar complaints where customers always report clanking noises from the chassis during braking. In reality, about 80% of such abnormal noises originate from the brake system: it could be the wear indicator tab on the brake pads scraping against the rotor, or possibly loose ball joints in the suspension's lower control arm. Once, a car owner thought it was chassis scraping, but upon disassembly, we discovered the issue was stuck brake caliper guide pins causing poor brake pad retraction. My recommendation is to first test with gentle braking in a safe open area. If metallic scraping sounds persist, head to the workshop immediately. Have the mechanic check while also using a pry bar to test for play in the lower control arm.
Last month, I encountered this issue while picking up my child—there was a screeching sound like metal scraping when braking. I asked a mechanic I know, and he said it's common for brake discs to rust after rain or car washing, causing noise during the first few brakes. However, in my case, the noise persisted for a week. Upon inspection, it turned out the anti-vibration shim behind the brake pad was deformed. Another easily overlooked issue is forgetting to install spacers when modifying rims, which can cause the inner side of the rim to rub against the brake caliper. Now, during every maintenance session, I make sure to check both the brake pad thickness and the spring clips.
