By Fred Pack, PCA DE instructor
Brake in a Straight Line!
I was recently at a Driver Ed event at the New Jersey Motorsports Park Lightning track. During a novice session I saw cars in two separate incidents spin off the track backwards straight ahead going into Turn 1, with fortunately no damage to car or driver due to the large grass run-off area.
The fact that there were two such similar and potentially very dangerous incidents during one event really concerned me, made me think about the underlying root causes and prompted me to write this article.
The first, general, point to make is this: Cars today are much faster than in the past. As example, the 2013 Porsche Boxster has 265 hp, versus the 200 of the 2000 model, and the 2013 Boxster S has 310hp versus the 250 of the 2000 model. The 2004 GT3 had 380 hp; the 2014 GT3 has 475hp. In each case, that’s more than 25% additional power. Turn 1 at Lightning is at the end of a long straight, so with all that power you are going very fast as you approach it and if you don’t brake adequately you can very easily be going too fast for the car’s capability or your ability to negotiate the turn. The very first general thing a novice driver should appreciate is that your high-performance car, even if it is a Ferrari 458, still has to honor the laws of physics – simply put they are: for every corner there is a maximum possible speed, no matter how good the car (or driver) is.
Driving on a race track is tremendous fun and very exhilarating but there are many, many things you have to know and appreciate – that’s why novices are always provided with an on-board instructor. Sometimes, though, a situation may arise so suddenly that the instructor can’t always guide the novice through it, and that’s what happened at Lightning.
Why did the two cars go off the track backwards?
I don’t have video of these incidents but almost certainly here’s what happened: The cars were going at least 100mph as the turn approached. The drivers got on the brakes very hard but entered the turn too fast -- or at least they felt it was too fast. They turned the steering wheel to the right while still braking hard (since they felt they were going too fast.) Immediately their cars did a 180º turn and they shot off the track facing backwards.
The reason for the mishap is that when a car is under braking weight is transferred from the rear of the car to the front – we all know that the nose dives under braking. This is because weight has been transferred to the front from the rear. (Conversely, under acceleration the nose rises, due to the weight being transferred to the rear from the front.) When weight is added to a tire’s load it has more grip with the road. Conversely, when weight is removed from a tire that tire has less grip. So those cars at Lightning had extra grip in front and less in the rear when the drivers initiated their steering. This caused the car’s front end to dart to the right, while the rear end lagged behind due to its reduced cornering grip. Instant 180º! The situation was made worse for the drivers because they were both front engine cars with substantial weight bias to the front – one was a BMW and the other a Honda.
What should the drivers have done to avoid these problems?
The first lesson to be learned from these incidents is do not do serious braking in a turn. (See NOTE below.) It may provoke just the kind of oversteer which is illustrated here. Brake in a straight line in advance of the turn-in point.
When entering a turn too fast as in Point 1, the solution is to stay on the brakes while going straight (or almost straight) to let the car slow down enough that you can complete the turn on the pavement. Yes, you will definitely be off-line and will lose time on that turn, but that is a much smaller price than going off the track entirely or hitting the tire wall.
NOTE: There is an advanced braking technique called ‘trail braking’ in which the turn is entered with light braking still underway. This intentionally reduces rear grip to promote some ‘rotation’ of the rear to aid in getting around certain turns. It is only valuable in certain turns and is not to be attempted by novices as it can cause a spinout if done improperly.