Quote:
Originally Posted by Pairadime
...the instructors last weekend told me that I need to trail brake as I enter turns and slowly release...
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This is turn-dependent. Some tracks call for very significant trail-braking; in comparison, some call for very little.
At the risk of way too much information, examples follow below. Each is a high-speed, former F1 track.
The first is
Mont Tremblant, a track requiring modest trail-braking, including two turns requiring only a short, sharp press of the brakes. The steering wheel is off by 10 degrees to the right in this video.
https://www.youtube.com/watch?v=2e3aaeSGgCI
In comparison to Namerow, note the steepness of the application and especially the release of the brakes in the turn under the Bridge. This despite the fact that both are uphill, straight-line braking zones. The 15 MPH increase in speed accounts for the trail-braking going up the hill to Namerow.
In contrast,
Watkins Glen is a very heavy trail-braking track, as shown in the video and the data traces that go with it.
Look how far this professional driver trail-brakes across the track going into many of the turns; he's holding the car at the very edge of the tires' adhesion.
https://youtu.be/NMdnioBa0E
The brake trace of the turns where the driver is trail-braking ½ or more across the width of the track shows just how much and how long he's trail-braking. The reason for the jaggedness of the brake pressure while trail-braking is because in addition to slowing the car as necessary, he's also
steering the car with the brakes. That is, the rising and falling brake pressure is keeping the car on a smooth and perfect arc from the turn-in point to final brake release.
At the turn-in point, the car has been slowed
only enough to allow it to turn in while maintaining the desired line.
From 1:03 to 1:07 in the video, the data overlay shows the driver using a rising and falling throttle to effect the same type of result, thereby allowing the car to smoothly turn down to the curb in the Carousel. In this car, pressing and releasing the throttle one or two credit card thicknesses was enough to produce the desired result.
Here the driver is shown using the brakes for ~460' going into the Bus Stop, finally releasing them just before he climbs up onto a significant curb at 90 MPH.
The purpose of this breakdown of the Bus Stop's braking zone is to show (generally) how a professional race car driver uses the brakes, especially the throttle-to-brake transition. (Not shown is the transition from no-throttle/no-brake back onto the throttle, which also has a "knee" in the throttle trace (i.e., the driver eases onto the throttle for ~1/10 of a second before fully opening it; on this lap, he reached full-throttle with the steering wheel turned 72° to the left.))
