Can you replace brake pads without replacing rotors?
That depends on the condition and thickness of the rotors and the amount of rust accumulation in the cooling vanes. If the rotor exceeds the discard thickness stamped into the rotor and if the rotor doesn’t have any deep grooves (deeper than 1/16”) and you’ve cleaned out each of the dozens of cooling vanes, then yes, you can reuse it. But just because you can doesn’t mean you should.
What happens when you install new pads on old rotors?
Used rotors aren’t flat like new rotors. That means the new pads won’t provide full stopping power until the pads wear into the shape of the rotor. Since only a portion of the brake pad is touching the rotor, it will create noise.
Why don’t shops replace pads without replacing rotors?
Because they don’t want the noise comebacks. Putting new pads on used rotors can cause noise complaints. The reasoning can be complicated but it boils down to this; even though the rotor looks perfectly flat, it isn’t. So the new pads don’t sit flat on the rotor until they wear into the unevenness. Until that happens, it’s like a stylus playing the grooves on an old LP record. The brake pad becomes the stylus and the micro-grooves on the rotor contain the “music”.
What can you do to reduce noise when replacing brake pads without replacing rotors?
First, try to match the new brake pads to the old brake pads. Don’t switch from organic to ceramic or semi-metallic to ceramic. Next, perform a brake pad “bedding” procedure. This involves applying the brakes to come to a complete stop multiple times to “embed” a layer of brake pad material onto the face of the rotor and accelerate the wear of the pad to the shape of the grooves in the rotor.
If you still have noise, you may have to resurface the rotor or replace it.
©, 2021 Rick Muscoplat
Posted on by Rick Muscoplat