Your Porsche – A school bus?

Your Porsche – A school bus?

Is your Porsche sounding like a school bus or garbage truck when coming to a stop?

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This can happen if you do a considerable amount of slower speed city driving, or stop-and-go driving in traffic, especially when using lighter brake pedal pressure. What commonly occurs is that a glazing layer will build up between the brake pads and brake rotors, due to a lower amount of friction/heat being present during the lower speed braking. This squeaking or screeching is a completely different issue than grinding, and can occur with any street brake pad compound—from factory/OEM to performance pads. One way to remedy this squeaking or screeching noise is to completely re-bed the brake pads and rotors, as this introduces a high amount of heat/friction which will help burn the glazing layer off of the brake components. We suggest following the brake component manufacturer’s recommended bed-in (ie brake bedding) procedures. After proper bedding, your brake squeak should subside (until you get stuck in stop-and-go traffic again, at which time the squeak may or may not return).

You will know when the bedding is complete when the rotor has an even shine on the rotor surface. Any spotting or blotting on the rotor surface is an indication that the pads are not yet fully bedded. Repeat the bedding procedure until the rotor surface is even.

An example of a bedding proceedure

Another potential cause of brake squeak can be brake dust which has built up considerably between the brake pads and brake rotors. Washing out this brake dust with a hose can help minimize this annoying squeak.

If you hear a grinding noise from your brakes, then it’s possible that you either have a small rock stuck between your pad and rotor, and/or your brake pad material is worn down to the pad’s metal backing plate. If the latter, then you will need new brake pads and rotors installed, as now the brake rotor(s) is grooved from being scored by the metal backing plate.

If you have any questions regarding this topic, please feel free to ask. No question is a silly question.

Jeremy Williams is the Oregon PCA Technical editor. He co-owns Matrix Integrated Inc. (Matrix Integrated Inc.) with his brother Justin. Jeremy can be reached at techeditor@oregonpca.org

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