Designing a Successful Pedal Box 2025-26

This page comprehensively covers the steps, considerations, and cautions needed to avoid failure

Steps

1. Calculations and miscellaneous planning

   1. Calculations on what pedal ratio; brake and accel*

      1. *Accel Pedal calcs are only for comfort and can be adjusted by buying a correctly specked tension spring (Ref. Optimal Accel Pedal Force → 4lbf)

      2. **Pedal Ratio can be generic to begin with (Start at around a pedal ratio of 3) and change later if need be

   2. Figure out what miscellaneous components need to be bought/integrated into design

      1. Brake

         1. Master Cylinder

         2. Balance Bar

         3. Brake Light sensor; rotational potentiometer, linear potentiometer, or limit switch

      2. Accel

         1. Tension Springs

         2. Accelerator sensor; rotational or linear potentiometer

2. Plan and design Mounting points for pedal box

   1. 2 flat tabs that are welded onto the frame w bolts? Vertically welded tabs? Try different mounting methods that works best with your design.

   2. Open

      

       

3. Preliminary design with integrated miscellaneous

   1. Make sure to include all nuts and bolts to check for any potential interferences

4. Simulation

   1. Simulate components most prone to failure

   2. Example Simulation Document from 2024

5. Prelim Design Review

   1. Set up a design review with Devansh, Kenta, Sohan Kureti, Advait Joshi

6. Make Changes (Iterate, iterate, iterate…)

Brake Pedal

The brake pedal is the component that causes the most failure within the whole assembly. When designing, things to consider include integrating the master cylinder, balance bar, and the brake light sensors. Along the way there are a few safety considerations to take as you design.

Integration of components

Current Master Cylinder to be integrated*: Tilton 78-series

Pull from Design Library: DL_TIL-78-625_Summit Racing_TILTON 78-Series Master Cylinder.SLDASM

*Note: Master cylinder can be changed if harder to mount onto pedal box base

**Ex. MC with a different mounting method

Consider how the master cylinder sits within the whole assembly. Is it going to be sitting behind the pedal, vertically positioned, under the drivers foot. Whatever position you decide to pursue, you need to keep in mind of the pedal ratio to make sure you are sending enough pressure into the brake line to meet brake regulations.

Open

MC Behind Pedal

Open

MC Sitting Vertical

Open

MC in front of Pedal

 

Balance Bar within Brake Pedal Assembly

Current Balance Bar to be integrated: Tilton 600-Series Pedal Assembly Balance Bars

Pull from Design Library: DL_TIL-72-262_Summit Racing_Tilton Balance Bar.SLDASM

*Note: Balance Bar can be changed for a longer one if it doesn’t work with design.

When installing a balance bar onto the brake pedal, a hole matching the sleeve’s outer diameter will be made in the pedal. The sleeve will fit concentrically in this hole and be secured in place by the clevises on both sides. *There doesn’t need to be a fixture that prevents the sleeve from moving out of place as long as the clevises are close together when assembled

Open

Brake Calculations

Brake Calculations are done as a way to figure out how much force is induced on the whole assembly and will help with simulations later on. As an ergo member, you don’t actually need to figure out the deceleration rate but rather the forces amplified onto the master cylinder from the driver input.

Pedal Ratio - Output/Input; Force input into MC/Force by driver

Open

Example Brake Calculations from Daybreak 2025

POC for Question regarding calculations: Kenta Yoshizaki or Sohan Kureti

Open

Generic Formula that works with MC laying flat

 

Open

Actual Brake Calcs with numbers from Daybreak 2025

 

Accel Pedal

The Accel Pedal is important in making sure that the driver controller knows how much voltage to send over to the motor. We don’t expect to see much force going to the accel pedal so no extensive simulations have to be done compared to the brake pedal.

Integration of components

• Rotational or Linear Potentiometer

  • Look into seeing if Rotational Potentiometer works in your design as it is more compact

  • *Considerations: Rotational Potentiometer has a dead zone where there is a certain portion at the beginning where it sends the same resistance. Integrate into your design in a way that the rotary potentiometer can be easily moved around a specific tolerance.

  • Pull Example Rotational Potentiometer from Design Library*: DL_HSTPSSAM810_HiSport (Rotary Potentiometer)

    • Does not have to be this rotational potentiometer; whichever one you find that works best with your design

• Tension Springs

  • Use tension springs bought from McMaster specked to the correct tension. Calculate the best pedal force necessary for the accel pedal and buy the right tensioned spring.

  • Potentially include hook areas in your pedal and base where you can hook on the springs on both sides. Ex. pedal has a thin metal shaft sticking out that you can hook the tension springs on

    Open

    

Simulation

Simulation is necessary to make sure that the pedal box doesn’t fail under the expected load that the driver applies. The simulation process is different from person to person but a valid way to simulate the brake pedal assembly (brake pedal, balance bar, mounting shaft, mounting tabs) under load is to hand calculate the forces induced in each component and doing part level simulations

Pedal Box Simulation Standard:

• Pedal box shall withstand a force of up to at least 1100N at a factor of safety of 1.4

  • Force found from physical testing done on how much force a driver can leg press

Minimum Parts to simulate for Pedal Box

• Brake Pedal

• Balance Bar

• Mounting Shaft

• Mounting Tabs

• Pedal Box Base