A Systematic Approach to the Analysis of Brake Noise

Brake noise is a complex phenomenon and a full understanding of it has eluded investigators for many years. Initially, methods of evaluating the noisiness of a given brake consisted of running it in a vehicle road test and recording the test driver's opinion of its noise characteristics. When a brake was judged to be excessively noisy, the friction material took the brunt of the blame, and the frequent approach to curing the problem consisted of running more vehicle tests using alternate friction materials. In this paper, a more systematic approach to the control of disc brake noise is suggested. First are described test methods, based on the use of modern techniques, including the Fast Fourier Transform Analyzer and Computer Data Acquisition Systems which replace or supplement tests where the output is the subjective opinion of a test driver. Second are described approaches to the design of quiet brakes which consider not only the friction material, but also the friction pad assembly and other components.