Cracks (Stress-Relief Microstructure) In The Brake Disc Friction Surface
WARNING: This page is about a different car, the 2024 Porsche 911, 2023 Porsche 911, and 2022 Porsche 911. However, it is still accessible from the selected car via links, so may be relevant.
Cracks in brake disc friction surfaces are viewed differently to cracks in grey cast-iron brake discs. Cracks in PCCB brake discs do not constitute a wear criterion but exist already in new brake discs because of the way in which they are manufactured.
Stress-relief microstructure in PCCB brake disc friction surfaces
Information
- Due to the composition of different materials in the friction layer and support body, the friction surfaces have an non-critical crack pattern (stress-relief microstructure). Individual relaxation cracks sometimes run along the perforated bores.
- The stress-relief microstructure results from the way in which the brake disc surface is manufactured and does not pose a risk to safety. There is also no danger of the friction layers flaking off from the support body because the friction layers are virtually free of internal stresses as a result of the stress-relief microstructure.
- The stress-relief microstructure is sometimes clearly visible in new brake discs and can be significantly different on the brake disc hub side and the side opposite the hub.