Brake Noise Resolution on the 1998 Mercedes-Benz M-Class 982245

This paper summarizes a case study involving the characterization and reduction of the brake noise on the 1998 Mercedes-Benz M-Class Sport Utility Vehicle. Noise was identified on both the front and rear brake systems. The front disc brake noise was described as a low frequency squeal, while the rear disc brakes exhibited a high frequency squeal.

Investigation into this problem incorporated vehicle and dynamometer testing as well as experimental modal analysis (EMA) for component characterization. The use of EMA and dynamometer testing resulted in the identification of several possible countermeasures including: pad chamfers, pad compressibility control, pad scorching, and rotor modifications. Various noise insulators were also examined as a potential solution to this problem without making any additional changes to the existing components. Dynamometer and vehicle testing were used in the evaluation and selection of a noise countermeasure for each the front and rear braking systems. For the final countermeasure, an insulator change was made on the front brake, and chamfers were utilized on the rear brake. Fleet evaluations have shown these countermeasures to be effective in reducing the occurrences of noise on the Mercedes-Benz M-Class.