As it can be seen from the simplified diagram, motor has 320 Nm of torque. And with the facture of safety, lets say of 3. total torque will be 3*320 = 960 Nm. I calculate the force on the motor housing from torque equation T = F * R, where the R is the inner radius of the housing. so the force is around 8.74 KN from the above equation. Now I have to decide the pretension force of the screw so that the motor housing will not rotate with the rotor. so how to calculate the pretension force on the screw. The thickness of the motor housing is 3 mm. there are total nine bolts(M8) in the assembly. your inputs are valuable to me. thank you in advance.