4x RejsaRubberTrac - no individual data except for FL (front left)?

I've built a system out of 4 equal ESP32 boards, the MLX90640s and with the distance sensors. It works nicely, I can see the tire temps for all four tires in the "analog" display (colored rectangles with the avg value). For the FL (front left) I can also add the digital value display for the individual data (like avg temp, temp1-8, distance, etc.). but for the other 3 tires, this does not work.
I got 4 bluetooth devices, named GT4_FL, GT4_RL, GT4_FR, GT4_RR. It's not a hwardware issue. If I swap the sensors, it's the same, only FL works. And as I see the colored tires (with the 8 ranges), something appears to be wrong with the individual data selection to show as digital text value.

Anybody experiences the same or has an idea?


  • Hi, please send a sample session (where all tires are recorded) to tracks(at)racehcrono.com
  • Good day! I have a similar story. I assembled two devices based on the nRF52 board. When connected to the RaceChrono, the temperature is displayed from both devices, but only the distance from the one that was added first. However, data recording is performed for both temperature and distance.
  • Yes, please send a sample too. This is most probably RC issue, that I can fix for upcoming v8.0.
  • Sorry, I had no chance to drive it yet due to the bad weather and record a session, hopefully in a couple of days.
  • Please find below the screenrecording. The values are there in the detailed view, but distance for FR is missing in the 4 tire display (end of video, bottom right). Same issue if I want to display any other individual value except for the FL.

  • @Richter if possible please send the session over to me :)
  • Sorry, I think there is no session file as there is no GPS signal in the garage. Or is there one? If the weather forecast holds, I can drive next weekend.
  • edited April 2023
    @Richter I think there's more than one issue. I think the distance measurement might be broken in the sensors displaying "0 mm". But the main issue, missing readings for the configured gauges, seems to be purely a RaceChrono bug.
  • Thanks for looking into it. I only have the distance for the front, no distance sensor for the rear. That's why for the rear tires it shows 0mm.
  • Here's a fully working setup. Only the rear cam view needs to be adjusted.
  • Nice job! I am working on a similar setup.

    Did you ensure that the sensor is installed so that it covers the area of the tyre and not less or more than that? I mean that all 8 readings are from the surface of the tyre?

    For example the rear tyres on the outer part are always blue. So either the sensor catches the temp of the air and not the tyre in this area or you may have too much negative camber.
  • edited July 2023
    Update: The fix to the issue in the original post did not make v8.0. I will try to fix it again in v8.1. It was more complicated than I expected.
  • @aol_of_RaceChrono : Thanks for following up. As the data recording is working fine, it's not critical for me.
  • @sikrip : Finding a mounting place is a challenge and it's difficult to have the right distance.On the front I'm now happy, the rear is difficult. There I use the 55 degree cam and seeing the tire is only within a small range. It's either seeing the track or the mud flap (or whatever that is called) if not within the exact direction. For the rear that's a bigger problem than the left/right. I can trim the left/right in SW, but gave up as it's not worth the iterations to get it perfect.
  • First tests with the potentiometer approach for measuring suspension travel are encouraging:

    Next I will add the tyre temp sensors.
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