Reduction of Groan and Grind Noise in Brake Systems 2011-01-2364
Low frequency brake system noise has been a systemic and ongoing issue for several automakers. The noise is a combined effect of brake and suspension systems working with each other. The noise transmission path is also important. The latest warranty and quality indicators on this has resulted in high degree of dissatisfaction for several vehicles. The customer complaints have been for grind noise, grunt and groan. The team focused on a multi-level integrated approach for this problem. The first step was deep diving and dissecting the customer complaint data. The low frequency noise for grind and groan can be reduced to several contributors. One of the main issues was the movement of pads over the rotor fins resulting in dynamic groan type of noise. It was important to relate this to the customer complaint for grind. In association with that, the grind noise was also caused by in-stop grunt type of noise. The grunt happens due to the stick slip of the pad material and the reaction of the suspension system. Considerable effort was put on finding the appropriate friction material to help with the noise.
Several incremental improvements were applied to reduce the noise. The next step was to understand and develop the dyno and vehicle noise prediction techniques. The testing method for Los Angeles City traffic was changed to more accurately predict the noise. Also, local vehicle testing methods were developed. After developing confidence in the testing, several possible counter measurers were applied. A new caliper and rotor design was developed. A new lining with innovative damping techniques was developed. The end result of this has been seen in customer cars and pre production builds.
This project resulted in substantial reduction brake noise. Also, new techniques for predicting low frequency noises along with innovative friction materials came out of this process.