The Reptiles team has been seeking a greater knowledge of the components used in the prototype. Commercial components are very important in the early stages, where the main focus is to make the system work. At the present moment, we are seeking to improve understanting of the theory, starting with the design of our own components. The first step has already been taken with all the team s brake discs. Corroborating the team s main goal of supporting PUC-Rio in the formation of better engineers. This work presents a methodology for obtaining the optimal sizing of an important mechanical component, the brake caliper in an onboard system of the current prototype of the Reptiles team. This part presents more complexity in obtaining the stresses in components to be added to it, such as the fluid seal and bolts. The first part of the methodology consists in determining the working conditions, considering the efforts made by the pilot and the multiplication of system forces, the braking resistance forces, and the supports to which the caliper is subjected. Then, the part will be modeled in Solidworks software, and structural simulations and topological optimization will be performed in Ansys software in order to have the knowledge of the regions with important structural function.