Car suspension system is composed of many links and the links are connected with rubber bushings. When forces from road excite tire, the forces are transmitted through rubber bushings and then vibrations of car body and interior noises are occur. Therefore it is very important to know correctly the transmission forces through rubber bushings to improve the ride comport and interior noise of car. This paper studied indirect method to estimate the transmission forces. By using vibration signals on links, vibration on elastic center of bushing can be estimated and then with known values of stiffness and damping coefficient of bushing, the transmission forces can be estimated. In the process of estimating the vibration on elastic center of bushing, sensors must be located properly to get independent vibration signals. This is studied in the simulation by using AUTOSIM, commercial simulation software to simulate multi-body system. In the experiment two tri-axial accelerometers and one-axial accelerometer are used to estimate the transmission forces.
