How to Determine When Car Brake Pads Need Replacement
3 Answers
Methods to check if car brake pads need replacement: 1. The vehicle dashboard has a brake pad wear limit warning light; generally, when this light comes on, it reminds the owner to replace the brake pads. 2. The thickness of brake pads is between 1 to 1.5 cm (may vary by manufacturer). When the wear thickness is less than 3 mm, the brake pads should be replaced promptly. 3. If there is brake caliper leakage, contaminating the brake pads and soaking into them, and oil stains are still found after sanding with sandpaper, the pads must be replaced regardless of thickness. 4. A decrease in brake fluid in the brake fluid reservoir. 5. Hearing a squeaking sound when braking is a reminder for the owner to replace the brake pads promptly.
As an experienced DIY car maintenance enthusiast, my advice focuses on three key aspects: thickness, sound, and pedal feel. Use your phone's flashlight to check between the wheel spokes - if the brake pad thickness is below 3mm (about two coin thicknesses), it's time for replacement. If you hear sharp metallic scraping sounds (like squealing) when lightly braking, this means the wear indicator tabs are grinding against the rotor, which severely damages the disc. I learned this the hard way - delayed replacement cost me an extra 800 yuan for new rotors. Now, whenever I smell burning after continuous downhill driving or notice the brake pedal feels spongy requiring deeper depression, I know it's inspection time. City drivers should check every 50-60k km, while mountain road users need inspections every 30-40k km.
Last week, while helping my neighbor's daughter check her car, I noticed iron filings accumulating on the right rear wheel. This is actually quite easy to diagnose: by observing the brake pad thickness through the wheel hub gaps. New pads are about 1 cm thick, and they must be replaced when worn down to 3 mm. Hearing a harsh grinding noise means the wear indicator is activated, at which point you can drive at most another 200 kilometers. I taught her to feel the brakes with her foot—if the pedal vibrates severely or needs to be pressed very deeply to stop, these are both danger signals. I remember one car owner who ignored the squeaking noise and ended up with deep grooves worn into the brake discs, requiring expensive replacements.