When Should Brake Discs Be Replaced?

[DelMiranda]

Brake discs need to be replaced at 70,000 kilometers, while brake pads require replacement every 30,000 to 40,000 kilometers. Conditions to determine whether brake discs need replacement: 1. A metallic scraping or squealing sound occurs when lightly applying the brakes; 2. The brake pad warning light on the instrument display serves as an indicator for brake disc replacement; 3. The total wear depth on both sides of the brake disc reaches 3mm. When the driver presses the brake pedal, a series of transmissions control the brake pads to clamp the brake disc. Over time, both the disc and pads will gradually wear down, and severe cases may even lead to fractures. These conditions can affect braking performance, and in extreme cases, complete brake failure may occur, potentially endangering lives.

[Archer]

Last time when I helped Uncle Wang check his car, I encountered this issue. I realized that deciding whether to replace brake discs shouldn't solely depend on mileage - it requires comprehensive judgment. Typically, new discs are about 20-30mm thick, and they need replacement when worn below the manufacturer's specified minimum thickness limit (which varies by vehicle model). During normal driving, if you experience steering wheel vibration when braking or hear metallic scraping sounds, these are warning signs. Personally, I make it a habit to inspect the disc surface every two brake pad changes, checking for severe grooves or cracks. Cars in northern winters with heavy de-icer usage require extra attention, as severe underbody corrosion may necessitate early replacement. Remember to have repair shops measure with calipers for accuracy - don't just take their word for it.

[JasmineRose]

As someone who works with brake systems every day, I consider wear thickness a critical metric. Factory brake discs have minimum thickness markings, and they must be replaced once worn down to that point. Routine maintenance focuses on three aspects: first, check for deep scratches exceeding 1.5mm on the surface; second, feel for raised edges or lips; third, listen for high-frequency abnormal noises during braking. Performance car enthusiasts should be especially vigilant—if a blue oxidation layer appears after aggressive driving, it signals thermal fade. The most easily overlooked issue is brake disc warping. If the steering wheel shakes severely when braking at speeds above 80 km/h, resurfacing won’t last long either.

[Lucille]

The repair manual states that brake discs typically last around 80,000 kilometers, but actual lifespan depends on driving habits. Frequent mountain driving or heavy loads accelerate wear, while city commuting can extend it to 100,000 km. Quick self-check method: insert a coin into the disc's groove - if the coin edge completely disappears into the groove, replacement is needed. Avoid aftermarket inferior discs; some poorly designed new discs may warp within a few hundred kilometers. When replacing discs, change brake pads simultaneously as old pads accelerate new disc wear. Surface rust isn't concerning (it wears off within kilometers), but rusted mounting bolts impair heat dissipation.