The performance and reliability of screw compressors depend significantly on the precise geometry and placement of the contact belt, the region where the male and female rotors engage along their helical profiles. This is significant for screw compressors, in which the male rotor drives the female rotor through the contact belt. This study investigates the effects of clearance variation on the force and sliding velocity in the contact of screw compressor rotors. By examining the sealing line between the rotors and adjusting the contact placement, this research aims to optimise the sealing efficiency, minimise leakage, and ensure effective torque transmission between rotors whilst maintaining reasonably low pressure and load on rotor bodies. The analysis considers the influence of different clearance variations and profiles, focusing on how these parameters affect force distribution, contact pressure, and sliding velocity. The key aspect of this investigation was achieved by using SCORG (an in-house computational tool) to place the contact belt to involute the pitch circle, which directly impacts the load and friction between the rotors. Preliminary findings demonstrate that optimising the contact belt placement can balance contact forces, reduce Hertzian stresses, and maintain acceptable sliding velocities, contributing to enhanced efficiency and longevity. This study highlights the trade-offs between stress reduction, leakage minimisation, and manufacturing tolerances, offering guidelines for the design and operation of high-performance screw compressors.