This study was performed for the optimizations of A-IMS assembly by analyzing the stress distributions under the different torque conditions. In order to achieve this, the numerical simulation was performed by SOLIDWORKS commercial code and the torque range that applied on the A-IMS assembly was increased from 10 N·m to 40 N·m. The simulation results were analyzed and compared in terms of Von-mises stress, principal stress, and displacement characteristics. The maximum stress distributions was observed on the contact surface of needle bearing which is located between tubular and solid shaft. It was found that the fracture of A-IMS assembly won’t occur until 30 N·m of torque. Therefore, it was concluded that there is no problem for the manufacturing of A-IMS assembly.