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Predominant brake noise evaluation and rating was developed many years ago and no longer fulfills the need of modern development work. An extended description of a noisy brake event (European expert group guideline EKB 3006) and a standardized test data exchange format, allowing the comparison of different source test results (EKB 3008) are presented. Today's noise rating systems are described and compared by selected examples. The paper proposes an open 4 level noise rating system (EKB 3007). It starts with simple occurrence statistics, noise rating based on sound levels, situational noise rating including duration and finally based on the human perception, described by psychoacoustics.

In the past, each noise shim supplier had its own specifications to describe the properties of their noise shims (often also called as shim or damping shim). Due to that, it was difficult to compare the physical properties of noise shims from different suppliers. The main task was to define common specifications for daily quality/development tests. Traceability in prototype status and production was introduced establishing a clear declaration of noise shim deliveries with batch no. and “use by” date. Harmonization was created through standardized tests and procedures. In addition, a common noise shim database for all noise shim manufacturers was established. A more realistic compressibility test was developed to estimate the additional compressibility of noise shims based on bare pads under cold and hot conditions. These values are important to describe the axial decoupling at low pressure and the maximal displacement at high forces.

Creep groan of vehicles is the low frequency chassis vibration occurring at very low brake pressure and extremely slow speeds giving the driver a very uncomfortable feeling. It is the classic example of a self-excited brake vibration caused by the Stick-Slip Effect. The essay discusses the mechanisms leading to self-excitement of vibrations. In the first section of the essay the state of the art is presented by way of a literature investigation and the phenomenon of creep groan is described. Then, by measuring the vibration characteristics of a creep groaning brake it is demonstrated that apart from a tangential brake caliper movement, a twisting of the brake around the vertical axle takes place. This twisting modifies the pressure conditions of the contact areas of brake disk and brake liner. Based on the measured results of adhesion and sliding coefficients a finite element model is developed simulating the dynamic processes in the friction layer using contact algorithms.