FSAE brake pedal

A complete brake pedal assembly for a Formula SAE electric car, designed for the AME27 Apprentice Mechanical Design Challenge.

2.13factor of safety at 2 kN

Render of the brake pedal assembly: aluminum pedal arm, twin Tilton master cylinders and balance bar on a base plate — View AFSAE EV brake pedal assembly

Project details
RoleSole designer: research, hand calculations, CAD and FEA		DatesFall 2026
ContextAME27 Apprentice Mechanical Design Challenge, Texas A&M Formula SAE Electric	ToolsSolidWorks, SolidWorks Simulation, Hand calculations

The assembly in 3D

Live model

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Click a part on the model, or pick it from the parts list.

Requirements and architecture

Rule T.3.2.2: the pedal must withstand 2,000 N at the pedal face without failure of the brake system, pedal box, chassis mounting or pedal adjustment.

The rules require two master cylinders, so I chose Tilton 78-Series (78-700) units on independent front and rear circuits, linked by a Tilton 72-250 balance bar. They come with return springs built in, which kept the design simple and compact.

After reading the rules I split the parts into what to buy (master cylinders, shoulder screws, bearing, locknuts) and what to design (pedal arm, base, switch holder).

Hand-drawn free body diagram of the brake pedal with the 2000 N pedal force, pushrod force and pivot reaction — Fig. 1Free body diagram, by hand

Pedal geometry and hand calcs

Floor-mounted pivot with the balance-bar clevis and the pad on the same side of it, the common FSAE pedal-box layout.

Clevis 45 mm above the pivot and pad 180 mm from it: a 4:1 pedal ratio, inside the typical FSAE range of 4:1 to 6:1. I kept the arm short to protect stiffness.

The pivot is a pin and cannot react a moment, so the peak moment sits at the balance-bar bore. The 12 mm arm tapers to be deepest there.

180 / 45 = 4 : 1
Pedal ratio: Typical FSAE range is 4:1 to 6:1; M ≈ 270 N·m
Peak moment at the balance-bar bore: 2,000 N × (180 − 45) mm = 2,000 N × 0.135 m

CAD and FEA

Imported the bought parts into a SolidWorks assembly and placed them with mates before drawing the arm, so its geometry was set by real hardware.

Ran a first FEA at 2 kN on the extruded profile, then added fillets for a lighter, easier-to-machine aluminum part and a tapered rectangular pad that spreads the load. The final study gives a factor of safety of 2.13.

Designed the base to be milled from one aluminum block, with arches and shoulder screws so the pedal and both master cylinders can rotate.

Found where over-travel occurs (36°) and designed an adjustable holder for the brake over-travel switch, a McMaster push/pull switch that stays latched once tripped, as the rules require.

Von Mises stress plot of the pedal arm under a 2 kN load at the pad — Fig. 2Final FEA, 2 kN at the pad: FOS 2.13

Side view of the pedal assembly in SolidWorks — Fig. 3Assembly, side view

Studio render of the pedal assembly from the rear quarter — Fig. 4Render, rear quarter

Render of the pedal assembly from the side — Fig. 5Render, side

Results

2.13
Factor of safety at 2 kN: ≈ 270 N·m
Peak bending moment: 4 : 1
Pedal ratio: 36°
Over-travel trip angle