This paper presents a brief introduction to lead and involute modifications. It describes their effect on gear tooth action. A gear tooth action study is presented which will enable the gear designer to predetermine the mechanical disturbances resulting from the uneven transfer of energy along the line of action.Kinematic features of acceleration and deceleration are depicted on a graph. The analysis presented will aid in the determination of proper involute and lead modifications required to weaken sound. It also presents a wear pattern determined by lead and involute specifications.