At what level of wear must brake discs be replaced?
3 Answers
Brake disc replacement criteria are around 2 millimeters. If the wear on the brake discs exceeds this standard, replacement should be considered. More knowledge about brake discs is as follows: Brake discs, simply put, are round discs that rotate as the vehicle moves. The brake calipers clamp onto the brake discs to generate braking force. When you press the brake pedal, the calipers clamp the discs to slow down or stop the vehicle. Brake discs provide effective braking performance and are easier to maintain compared to drum brakes. There are three types of brakes: disc brakes, drum brakes, and air brakes. Older vehicles often have disc brakes in the front and drum brakes in the rear. Many modern vehicles use disc brakes on both the front and rear. Because disc brakes dissipate heat better than drum brakes, they are less prone to heat fade during high-speed braking, making them more effective in such conditions. However, during low-speed cold braking, their performance is not as good as drum brakes.
I've seen too many brake disc wear issues at the repair shop. Generally, when the thickness drops to 80-85% of the original, it's time to replace the disc. Just use a simple tool to measure the thickness - if it's below the manufacturer's specified minimum, don't delay. I always remind car owners that discs that are too thin can warp from heat, reducing braking force by several times during emergency stops and increasing the risk of rear-end collisions. It's also important to check for surface cracks or deep grooves, as these can be warning signs. Measure the disc thickness during routine maintenance - you should check it every two brake pad replacements. Don't skimp on this for the sake of saving money. Safety comes first, and delaying replacement can damage other components like calipers, ultimately costing you more.
I'm just an ordinary car owner. Last time when my brakes were squeaking, I checked the disc thickness and it was less than 2mm, while new discs are 10mm thick. The mechanic said anything below 2mm must be replaced, or the brakes could fail completely. That really scared me, so I replaced them immediately. Usually, I pay extra attention when driving - if the pedal feels spongy or there's any unusual noise, I get it checked right away. The wear limit is generally below 20% of the original thickness, and things like cracks or deep grooves are also warning signs. Trying to save money by not replacing them? In the end, repairing damaged calipers costs even more. I've learned my lesson and now check every six months - safe driving depends on this.
