Roll die forming is investigated as a new process for manufacturing a clutch hub; in this process a tooth shape is formed by a deep drawing process using a die set with rotational rolls. Some problems are still encountered during roll die forming, such as a proper process design that takes into consideration the forming limit of sheet material, the improvement in the wear resistance of the punch and the rotational roll, and the control of dimensional accuracy. Particularly, the dimensional accuracy of the final product is affected by the clearance between the punch and the roll. Therefore, the objective of this study is to determine the optimal clearance between the punch and the roll for improving the dimensional accuracy during the roll die forming for a clutch hub. FE-simulation and the design of experiment method are employed to determine the optimal clearance required to produce a final product with satisfactory dimensional specifications. An experiment is performed under the same process conditions as the FE-simulation with an optimal clearance to validate the results obtained in this study. The results of the FE-simulation are in good agreement with the experimental ones within a maximum error of 5.55[%].