Considering the crucial function of Axle set, especially the vehicle brake drum due to its relevance to the safety of the passengers, the study of the producing and assembling processes and conducting the quality control experiments during these stages is of great importance. With regard to the great significance of three main factors, namely, seal-oil spindle diameter, seal-oil internal diameter, and nut lock torque as independent variables, the present research attempts to optimize the rotatory torque of the automobile brake drum (as the response variable) getting help from the discussions in the design of experiments and response surface methodology. In the following parts the amount of the optimum torque has been calculated using the non-linear programming model and genetic algorithm .