MIE.29 – Design of Pedal Box for Formula Combustion and Electric Racecars

• Vishek Masalia
• Jonathan Simon
• Pranav Vora
• Nicholas Whitney

The Society of Automotive Engineers Collegiate Design Series is an opportunity for engineering students to build vehicles and compete against other schools yearly. The University of Illinois Chicago chapter, SAE @ UIC, is designing their first electric racecar, the FE25 in addition to building their new combustion car, the F24. The previous combustion car, the F23, requires a redesign of the pedal box due to lack of rigidity under hard braking causing bending of the brake bias bar and overall pedal assembly. Since the F24 requires a more rigid pedal box and the FE25 will use a similar front chassis design for pedal box housing, the group was tasked with designing a pedal box compatible with both cars. Design alternatives differed primarily in pedal box structure and how master cylinders were mounted. Pedal box structure alternatives consisted of a baseplate or tubular structure, while master cylinder mounting alternatives consisted of static or rotating cylinders, attachment above or below the brake pedal pivot, and location in front of or behind the brake pedal. The selected design consisted of a 4130-steel tubular structure combined with a 6061-T6 aluminum baseplate to maintain strength while reducing weight. Rotating master cylinders located behind the brake pedal were chosen to improve direction of forces into the pedal box structure. Additionally, a fastened, rather than welded design was chosen to improve manufacturability and cost. To ensure strength and reduce the likelihood of failure, static structural simulations of the baseplate and pedals were performed in ANSYS. Boundary conditions were obtained using free body diagrams with applied forces from the driver and criteria from the 2024 FSAE rules. Initial validations of the selected design were performed with prototypes made from laser-cut acrylic to ensure proper fitment. With reduced deflection under hard braking, lower weight, and lower cost, the updated pedal box is a sound improvement over the previous one.