How to find braking points from a speed trace
If you do not have brake-pressure data, the speed trace still shows where the car starts slowing down. That is close enough to compare laps. Just call it the start of the slowdown—not the exact moment your foot touched the brake.
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Slowing
The main idea
A useful braking comparison includes onset, intensity, duration, and what happens after release. Later onset is not better if it forces excess slowing, disrupts the line, or delays acceleration.
What to look at
- A sustained speed decrease rather than one noisy sample
- Negative longitudinal acceleration
- Distance from a repeatable landmark
- The resulting minimum and exit speed
Try this
- Overlay speed and longitudinal acceleration
- Mark sustained slowdown onset
- Compare how rapidly speed is removed
- Inspect the release or transition into lateral acceleration
- Follow the delta through corner exit
Keep in mind
Without a pressure or switch channel, data cannot prove when the pedal was pressed. Lifting, engine braking, gradient, wind, a shift, and drag can all contribute to deceleration.
FAQ
Can GPS show my exact braking point?
It can estimate where the vehicle began sustained slowing. Exact pedal application requires a direct brake channel.
Why use longitudinal acceleration too?
It helps distinguish a sustained deceleration event from small speed noise and shows the shape of the slowdown.