Suspension system provides a function to stabilize the vehicle when it travels on uneven roads. A passive suspension system consists of sprung mass (body vehicle), unsprung mass (wheel), spring and damper with fixed characterization. However, variability in unsprung mass possibly to occur due to changes in the type of damper employed and variability in the damping coefficient is possible due to the type of damper employed which is being a pneumatic, hydraulic or magnetorheological damper with a different damping coefficient. This research analyzes the sprung mass and damping coefficient as parameters that were characterized to the system’s natural frequency. This research proposes an objective function in the frequency domain to determine the optimum damping coefficient value to reduce/mitigate the effect of variability of parameters to the sprung mass displacement and the relative displacement of sprung mass—unsprung mass.