Saving the brakes

If you’ve been following along, you know that last week we placed 3rd in a 24 hour endurance race and that we had to make a set of pads last as long as possible. With 2 drivers left, there was about 2 mm of pad remaining. So the plan was to save the brakes. The next driver in decided to completely ignore those team orders and drive as fast as possible. How do I know? By looking at the telemetry. I can also see that he needs some coaching on how to drive. So let’s take a look at the traces. You’ll probably want to open this in another window to see the details.

The blue and red lines are driver #1 (going as fast as possible). The green and black lines are driver #2 saving the brakes (green) and driving faster on the very last lap of the race because there were no brakes to save (black). The panels are speed, RPM, throttle, and time differential going top to bottom.

  • At 1100 and 1400 feet, the red line speed graph hits the bottom of the graph. Driving so fast that one runs off track (1100 ft) and spins the car (1400 ft) in the same lap were not part of the plan and could get you pulled from the car.
  • The plan was the green line. Notice how the slope of the line goes gradually down at 8500, 10000, and 13500. Driver #2 is coasting into braking zones. As you can see from the RPM trace, he’s using the gearbox to help slow the car. Normally, that’s a no-no, but in this case, we wanted him to do that. My favorite part is that he hits the same minimum speed at 9000 ft on his fast and slow laps. He has planned out how to arrive at the same speed at the most critical corner without using any brakes. Well done.
  • The blue and red traces generally follow the black trace on the speed graph. The speeds of the black line are higher everywhere, which is why the lap time was 2:29 rather than 2:32. The deceleration slopes are similar. This indicates that driver #1 was hitting the brakes hard. Nooooo.
  • Do you see the weird throttle blip at 1300 feet on the red/blue lines? That’s not a downshift, but an upshift. Is that some kind of slam shift technique I’m not aware of?
  • Look how the black line gets to 100% throttle and stays there. That’s how to go fast in a momentum car. There should be very little time at partial throttle in the Yaris. The red and blue lines are often at partial throttle. This is because the driver lacks confidence when the tires are slipping in a corner. Tires are supposed to slip.
  • Driver #1 has some misconceptions about how to drive fast. It’s not about braking as late and hard as possible. The fastest drivers did 2:26 on this track. You can’t make up 6 seconds by braking late. You have to enter faster, back up the corners, get to 100% throttle before the apex, and leave it there until the next corner.

So driver #1 has some learning to do. We all do. The car finished higher than it had any right to so I still wouldn’t change anything about the weekend. Except maybe eat another bowl of tortilla soup. I should have done that.

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