Lebois Racing

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May 31, 2020 / 3 Comments

SRT brake pedal P1 v5.3

The SRT P1 brake pedal is based on the following principle: connect your pedal to a real brake system! Impossible to have a more realistic feeling !

You want to support this project ? https://www.paypal.me/leboisVR?locale.x=en

Summary:

  1. Presentation
  2. Features
  3. Shopping list
  4. Assembly instructions

For info: I do not sell ANY PEDALS OR PRINTED PARTS. That would be trading, and I am not, and do not wish to be a trader. I don’t do black either. No need to ask. However, I am looking for a company that could produce plastic parts for those who do not own 3D printers. If you know of any…

1) Presentation

The P1 brake pedal uses a pocket bike brake calipper.

2) Features

You can tune the lever position by adjusting the bearings position.
There is a screw to add a preload on the master cylinder, so you can shorter the phase of the travel that is very soft.
I use a hydraulic pressure sensor. It acts like a potentiometer. You got only three wires : red (3.3V or 5V), black (ground), green (signal).

Regarding the support:
– Wood version will use wood screws to fix the support to the ground.
– M6 version will use M6 screws to fix the support to the ground.

The Rev2 modifies the system. More informations about the REV 2.

Here is the pictures of the brake pedal (v5.3) REV1:

And in Rev2 :

3) Shopping list

Electronics:

  1. Hydraulic pressure sensor 500psi 1/8″ NPT (Amazon, Aliexpress, Ebay).If you push EXTREMELY hard you might consider using a 1000 psi sensor. I never exceeded 60%.
  2. Cables 3cores 22awg (outer diameter is 4mm).

Mechanics:

  1. Brake caliper : Single piston (A) (Amazon, Aliexpress, Ebay), Double pistons (B), 4 pistons (C)
  2. Master cylinder : Willwood or OBP or Ali
  3. 1kg PLA (Amazon)
  4. 2 bearings KP001 12mm (Amazon, Aliexpress, Ebay) (Each SRT pedal requires two 12mm KP001)
  5. 1 M8 rod end for Ali master cylinder, or this one for the Willwood and OBP. 
  6. 1 Banjo M10x1.25 with pressure sensor mount (Ebay) (goes between the brake calipper and the pressure sensor).
  7. 1 Banjo UNF 3/8-24UNF (Aliexpress, Ebay) that goes on the master cylinder.
  8. 1 brake hose (Amazon, Aliexpress)
  9. Joints

Screws :

– 1 x M5x50mm DIN912 for the preload (Aliexpress)

– 2 x M4x20mm Flat Head Countersunk and 2x m4 nuts. This Amazon kit contains the two screws and many others that will be useful for other projects.

– 3 xM8x35 : 2 for the master cylinder, 1 for the M8 rod end. (Aliexpress)

– 1 x M12x100 metal axle (Amazon, Aliexpress, Ebay)

How to choose the master cylinder ? A priori, there are many master cylinders compatible. The chinese model is the one that I have been using almost since the beginning, and it clearly does the job. Otherwise you can use other brands. Beside the dimensions, you need to mind foor numbers :

– Thread inlet : for the oil reservoir. If it’s not integrated, you need to find one.

– Thread outlet : This is where the banjo is installed, so it needs to match the banjo thread. The one advised above is 3/8″-24 UNF.

– Piston axle thread : it needs to be M8, because the rod is M8.

– Piston diameter : bigger = shorter stroke and harder resistance. The advised master cylinder is 0,7″.

4) Assembly instructions



1) Install the master cylinder in the master cylinder holder

  • Use one M8x35mm bolt and M8 nut for each hole.
  • The head of the lower bolt goes at the back.


2) Install the M8 rod end in the brake lever

3) Use one M8x35mm screw to secure the M8 rod end. It should tight into the plastic

4) Slide the M12 Axle into the brake lever

5) Slide the KP001 bearings to the M12 axle

6) Fix the KP001 bearings to the ground

7) Screw the master cylinder axle into the M8 rod.

8) Fix the master cylinder support to the ground.

9) Build the hydraulic system

(to be continued soon)

May 31, 2020 / 0 Comments

Interfaces for the pedals

Here are all the solutions to plug your SRT pedals. Two philosophies: connect the pedals to your steering wheel, or connect the pedals directly to the computer.

Table of contents

  1. Logitech (G27, G29, G920)
  2. Simucube 1
  3. Simucube 2
  4. Arduino
  5. Leobodnar
  6. Thrustmaster

The vast majority of pedal sets use potentiometers. As the accelerator is based on a potentiometer, and the hydraulic pressure sensor also behaves like a potentiometer, you can connect this pedal sets to most of the steering wheel bases (logitech, Simucube, Thrusmaster…).

Alternatively it can be connected to a Leobodnar or Arduino card which is then connected to the PC via a USB cable.

1) LOGITECH (G27, G29, G920…)

You can connect the SRT pedal set to a G27 or G29 steering wheel. To do so, use a VGA male connector with the following pins:

1 – Ground (0v)

2 – Accelerator

3 – Brake

4 – Clutch

5 –

6 – VCC (+5v)

7 –

8 –

9 – VCC (+5v)

 

2) SIMUCUBE 1

The pedals can be connected to the X11-upper port. See details on the Simucube documentation.

Pin 1 is the rightmost one. A RJ45 (8P8C) cable must be used.

1 – Brake

2 – Throttle

3 –

4 – VCC ( +3,3V)

5 – Clutch

6 –

7 –

8 – Ground (0V)

 

3) SIMUCUBE 2

There is a “SC accessory port” on which there are pins to connect pedals, it’s female vga db15.

See the documentation available here. You can use this type of male connector. The pins you are interested in :

2 – Ground (0V)

6 – Throttle

7 – Clutch

8 – VCC (5V)

13 – Brake

15 – Ground (0V)

4) ARDUINO

If you don’t want to plug the pedals into your steering wheel, using an arduino card is the cheapest solution. The following code allows you to manage from one to three pedals. It only works with Arduino Leonardo and Micro cards (fitted with ATmega32u4 CPU). The Joystick library can be downloaded here.

// V1.0 : ajout du mode verbose
// V1.1 : correction
// Disable verbose mode once you have calibrated your pedals to make work at full speed !
// comment either out to disable || Mettre en commentaire pour désactiver

#define USE_ACCEL
//#define USE_BRAKE
//#define USE_CLUTCH
#define VERBOSE_MODE   //allow to tune min and max

int AcceleratorPin = A0;
int BrakePin = A1;
int ClutchPin = A2;

int minAccelerator = 210;
int maxAccelerator = 595;
int minBrake = 0 ;
int maxBrake = 1023;
int minClutch = 0;
int maxClutch = 1023;

int lastAcceleratorState ;
int lastBrakeState;
int lastClutchState;
int currentAcceleratorState;
int currentBrakeState;
int currentClutchState;

#include "Joystick.h"
Joystick_ Joystick(JOYSTICK_DEFAULT_REPORT_ID,
                   JOYSTICK_TYPE_MULTI_AXIS, 4, 0,
                   true, false, false, false, false, false,
                   false, false, true, true, false);

void setup() {
#ifdef VERBOSE_MODE
  Serial.begin(9600);
  Serial.println("Verbose mode activated");
#endif

  Joystick.setXAxisRange(minClutch, maxClutch);
  Joystick.setAcceleratorRange(minAccelerator, maxAccelerator);
  Joystick.setBrakeRange(minBrake, maxBrake);
  Joystick.begin();
  lastAcceleratorState = analogRead(AcceleratorPin);
  lastBrakeState = analogRead(BrakePin);
  lastClutchState = analogRead(ClutchPin);
  delay(1000); //safety delay to flash the code
}

void loop() {






#ifdef USE_ACCEL

  int currentAcceleratorState = analogRead(AcceleratorPin);

  if (currentAcceleratorState != lastAcceleratorState)
  {
    Joystick.setAccelerator(currentAcceleratorState);
    lastAcceleratorState = currentAcceleratorState;
  }
#ifdef VERBOSE_MODE
  Serial.println("acceleration ");
  Serial.println(currentAcceleratorState);
  delay(500);
#endif
#endif

#ifdef USE_BRAKE
  int currentBrakeState = analogRead(BrakePin);
  if (currentBrakeState != lastBrakeState)
  {
    Joystick.setBrake(currentBrakeState);
    lastBrakeState = currentBrakeState;
}
#ifdef VERBOSE_MODE
    Serial.println("frein ");
    Serial.println(currentBrakeState);
    delay(500);
#endif
#endif

#ifdef USE_CLUTCH
  int currentClutchState = analogRead(ClutchPin);
    if (currentClutchState != lastClutchState)
    {
      Joystick.setXAxis(currentClutchState);
      lastClutchState = currentClutchState;
    }
#ifdef VERBOSE_MODE
    Serial.println("embrayage ");
    Serial.println(currentClutchState);
    delay(500);
#endif
#endif

    delay(10);
  }
Arduino code.

 

5) LEOBODNAR

This adapter allows you to connect the SRT pedals without having to manipulate a code. Indeed, Leobodnar provides an easy to use software that allows to calibrate the pedals.

I created a junction box: a male VGA connector on one side, and three output cables (diameter AWG22, it’s the one indicated in the pedals stroke list. There is an anti-tearing system that ensures reliable operation. The 3D files are on Thingiverse. The male connector can be ordered here on Amazon, or Aliexpress.

6) THRUSTMASTER

The Thrustmaster T-GT, T300, T150, TS-XW, TX and TMX steering wheels are connected to the pedal sets though an RJ12 6P6C (6-wire) cable. If you don’t know where the 1 is on your cable, look at the color codes on Google.

1 – Brake

2 – Throttle

3 – Clutch

4 – VCC ( +5v)

5 – Ground ( 0v)

6 – Ground ( 0v)