Do Brake Pads Need to Be Replaced When Changing Brake Rotors?
2 Answers
Replacing brake rotors does not necessarily require replacing brake pads. If the brake pads are still thick, you can change the rotors without replacing the pads. It depends on the situation: Brake rotors typically need to be replaced after two sets of brake pads. When the combined groove depth on both sides of the rotor exceeds 3mm or the edges become sharp, it's time to replace them. When purchasing brake pads, pay attention to the "Four Checks and Two Choices." Here are the details: 1. Four Checks: 1. Check the friction coefficient, which determines the basic braking torque. Too high can cause wheel lock-up, loss of control, or pad burning; too low increases stopping distance. 2. Check safety. Brake pads generate instant high temperatures during braking, especially during high-speed or emergency stops. High temperatures can reduce the friction coefficient. 3. Check comfort, including braking feel, noise, dust, smoke, and odor, which directly reflect friction performance. 4. Check lifespan. Typically, brake pads should last for 30,000 kilometers. 2. Two Choices: 1. Choose brake pads from reputable manufacturers with license numbers, specified friction coefficients, and compliance with standards. The packaging should include a quality certificate, production batch number, and manufacturing date. 2. Choose professional repair shops for installation by qualified technicians.
Replacing brake discs doesn't necessarily mean you have to replace brake pads, but based on my years of auto repair experience, it's best to change them together. I've encountered many car owners who tried to save money by only replacing the discs, only to end up with uneven wear on the old brake pads, causing screeching noises during braking and even longer stopping distances - a major safety hazard. I remember a friend last year whose car almost rear-ended someone on the highway precisely because he only replaced the discs but not the pads, resulting in poor break-in and brake failure. Generally speaking, brake pads must be replaced when their thickness falls below 3mm or reaches the manufacturer's recommended lifespan. New discs have smooth surfaces while old pads are rough, which can easily cause scratches or uneven wear, ultimately shortening the disc's service life too. My suggestion is: if discs need replacement, check the pads at the same time. If they've been used for over three years or driven more than 50,000 kilometers, just replace them directly to avoid repeated garage visits and unnecessary expenses. Safety comes first - don't risk it just to save a few dozen bucks.
