How deep should brake disc grooves be before replacement?
2 Answers
Brake disc grooves exceeding 1 millimeter require replacement. The wear limit for brake disc grooves is 2 millimeters. If the grooves are not deep, the brake pads can be removed and smoothed with coarse sandpaper, then reinstalled. During use, this can help eliminate the grooves on the brake disc. Owners may opt for softer brake pads, which wear out faster but are less likely to cause grooves on the brake discs. For deeper grooves, the brake disc can be removed and the grooves smoothed out, a process commonly known as brake disc resurfacing. After resurfacing, the disc can be reinstalled and used, though its lifespan will be shortened, so direct replacement is recommended. Front brake discs typically need replacement every 60,000 to 80,000 kilometers, while rear brake discs should be replaced around 100,000 kilometers. Once the grooves reach the wear limit, they can affect the vehicle's braking performance. For safety reasons, it is essential to replace the brake discs with new ones.
I've previously helped people deal with many brake disc issues at the repair shop. Based on my experience, grooves on brake discs are mainly caused by metal friction marks from worn brake pads, and they need replacement if the depth exceeds the standard. Generally speaking, when groove depth reaches 1.5mm or more, it indicates high risk—many automakers like Toyota or Honda specify this threshold in their manuals, as it may lead to reduced braking performance, such as longer stopping distances, vibration during braking, or increased noise. You can measure groove depth with a vernier caliper. If you find localized deep spots averaging over 1mm, that's also cause for concern. Remember: safety first—never cut corners. It's best to inspect the braking system every six months and check brake pad thickness to determine if combined replacement is needed, preventing potential stall accidents. Addressing these minor issues promptly extends vehicle lifespan while saving time and hassle.
