The harness tensioner allows for a limited budget to make the negative Gs (braking, ABS, shifting) credibly felt. It works with Simhub.

Final rendering: frankly very nice. At the first braking, we say to ourselves “Well, maybe it wasn’t worth the trouble…”. After a few laps we forget it. Then it’s when the belt doesn’t work anymore (yes because at the beginning, there were some tests…unsuccessful ^^) we can’t do without it anymore… we have again the feeling to play a video game, and not to drive a race car…

The system is quite precise, it engages immediately, and you can feel the braking difference between an F1 and a base car, you can also feel the activation of the ABS.

It’s probably not precise enough to use the information to dose the brake, like “ah it’s not working for me, I can brake more”.

NOTA BENE :  The harness tensioner can be dangerous. At full power, it is very stressfull around the clavicles. Therefore, an emergency stop button must be installed.

Want to support this project ?

Summary :

  1. Presentation
  2. Caracteristics
  3. Shopping list
  4. Building instructions


1) Presentation

The harness tensioner consists of a harness (4 or 5 points), an electric motor, an electric motor driver, and an arduino board connected to Simhub.

2) Caracteristics

The motor pulls the belt backwards, it gives the impression of being thrown forward, especially in VR.

3) Shopping list

Electronics :

  1. A 350W electric motor.(Amazon, Aliexpress, Ebay)
  2. 24V  15A 360W Power supply. It can good a good idea to add an emergency stop (Amazon, Aliexpress, Ebay)
  3. Motor driver (Amazon, Aliexpress, Ebay)

Mecanics :

  1. A 5-point harness. 4 points do the trick (that’s what I use). When the motor pulls, the buckle goes up, but once everything is under tension, you can feel the effort in your shoulders, so no worries.(Amazon, Aliexpress, Ebay)
  2. 0,1kg PLA (Amazon)to print the rewinder. I would like to add a mechanical preload system to make the belt lightly preloaded at rest.
  3. Bicycle brake cable (Aliexpress).

4) Building instructions

The belt retractor is mounted on the motor shaft. Caution, the motor shaft is in reverse pitch, so do not lose the nut.

The connection of the power supply and the motor to the driver is indicated on the PCB.

Cut the electrical connection (with a cutter for example). (thanks to Banfy211 from RacingFR to get rid of the RC circuit previously used)

Connect the leg of the resistor to the pin 9 of the Arduino.

Connect the ground of the PCB to the ground of the Arduino.

On Simhub: We flash an arduino with the PWM signal function (usually used to drive fans to make a wind simulator) and we associate the deceleration function to it.