Abstract
Disc Brake noise can be roughly classified as squeal or groan, with frequencies of 1000Hz to 15000Hz and 50Hz to 500Hz respectively. The suppression of both types of noise is important for vehicle driving comfort. Many studies have been made and published about squeal; however, few studies have been published about groan. What is simply called "disc brake groan" actually consists of four species of groan classifiable by generation mechanism. The scope of this discussion is the basic studies and experiments which were conducted focusing on rumble groan, which is one of the major issues in the market. We confirmed the generation mechanism and some preventive measures.