In the 2023-2024 season with Longhorn Racing, I became part of the vehicle brakes team, dedicating the initial months to extensive research on brake systems and vehicle dynamics, alongside performing calculations to optimize braking efficiency. Our primary objectives were to reduce the size of the brake calipers for weight savings without surpassing system pressure limits, and to refine the brake rotor design to enhance cooling, reduce weight, and endure the load demands placed on the rotors.
At the beginning of the season, during dynamic events with the previous year's car, the brake rotors experienced a catastrophic failure, breaking in three places. This incident proved to be a valuable lesson in brake rotor design, igniting discussions on the merits of slotting versus drilling rotors and highlighting the importance of selecting the appropriate material for the new design. Further analysis suggested the failure was due to drilled holes being too close together, reducing cross-sectional area and leading to structural weakness, compounded by the cast iron rotors reaching a temperature at which the material integrity was compromised.
To qualify for the dynamic events in FSAE, it's mandatory for all four wheels of the car to achieve lock-up, necessitating precise hand calculations of braking torques, tire forces, longitudinal forces, and other braking dynamics. This year, our aim was to reduce caliper size while increasing line pressure for more effective braking. We selected Brembo P2.34 calipers for the front wheels, chosen for their lightweight, efficiency, and ability to handle high brake line pressures, aligning with our design goals.
The redesigned rotor utilizes a slotted hole path for enhanced cooling, constructed from 4130 steel to balance manufacturability with the necessary strength to withstand high stress and ensure compatibility with our chosen brake pads. Care was taken to maintain the cross-sectional area within safe limits to support the load cases, specifically addressing the demands on the front wheel, which experiences the highest stress. This consideration led to the inclusion of six brake buttons in the floating rotor design to accommodate significant longitudinal forces.