On Stopping And Driving Around Obstacles

Published: February 8, 2014

As you start driving faster and closer to the physical limit of the car, an important thing to realize is you lose the ability to stop the car or radically alter its trajectory on the spot.

At 6/10, if you decide you are coming into a corner too fast and lock up the tires braking in a straight line, you have good chances of stopping either on pavement or just off pavement. This is because your corner entry speed is, let's say, 35 mph, and you coast between the end of your braking zone and your turn in point. If you spend the entire distance of pavement from your normal braking point to until the pavement turns you can often bring the car to a stop.

At 9/10, you might be entering the same corner at 50 mph and you don't coast between the braking zone and your turn in point. In fact, if you are trailbraking you might turn in at 55 mph and drop to 50 mph somewhere between the turn in point and the apex. There is no way you will be bringing your car to a stop in two car lengths or so of pavement from 55 mph. If you lock up the tires and go off straight, and there is no sand trap in that corner, you are much more likely to hit a wall.

Advanced drivers, therefore, typically do not have as their recovery goal to stop their vehicle. Rather, continuing with our fictional corner, their goal might be to slow the car down to 45 mph and turn in from the end of the pavement, essentially running an extremely late apex. The expected 45 mph turn in speed, while still higher than 35 mph a novice would have, is below the normal 55 mph turn in speed of the advanced driver, and might be within grip limits of the car.

Similar reasoning applies to avoiding curbs and debris/animals on track. If a novice turns in too soon at 6/10, they can correct their trajectory with steering input and avoid going into the apex curb. At 9/10, avoiding the curb will in fact result in a significantly early apex with the likely consequence of the car departing the track at corner exit. It is often much safer to instead cut the apex curb. Cutting the apex curb takes grip away from the front tires, which will produce some understeer, but will maintain the general trajectory of the car and make it fit into the track at corner exit. Dropping the loaded outside wheels at corner exit has good chances of spinning the car.

Trying to avoid debris or animals on the track often leads to rollovers. Hitting debris might damage the car, but the damage is likely to be limited to the bumper, and probably one side of the car. A rollover often destroys the car and can, and has, caused significant injury to its occupants.

If you have ever driven over a big pothole on the street while turning, you know that the vehicle changes direction significantly as a result, and typically this direction change needs to be countered by the driver. At track speeds the driver typically cannot counter the direction change resulting from an abrupt steering correction.

Accept that you might come across debris on the track, and be prepared to maintain your course and drive over it.

Tagged: intermediate, vision