–
–
No one has ever understeered their way to driving glory. In addition to being the enemy of driving pleasure, understeer, if potent enough, has the magical ability to reshape the front end of your car. It’s bad.
–
Pendulum turns and left-foot braking, practices common in the world of low-grip driving, also happen to be understeer’s greatest foes. This test measures the effectiveness of those techniques. The goal, in this case, is to destabilize the chassis and point the drive wheels in the desired direction, allowing earlier throttle application and faster exit speed than is achievable using conventional road-racing techniques. Or so goes the theory.
–
–
–
Tim O’Neil, winner of five U.S. and North American rally championships and founder of the Team O’Neil Rally School, says there are multiple benefits of left-foot braking. High on his list: correcting understeer, inducing oversteer, and aiding timing in changing the direction of a slide. The great philosopher Sammy Hagar might have immortalized the notion of using one foot on the brake and one on the gas, but O’Neil helped perfect it.
–
–
Despite these benefits, carmakers and lawmakers alike take a dim view of destabilizing anything, especially a moving car. Accordingly, the practical application of this kind of driving is relegated to low-grip rally stages, rallycrosses, and other places less susceptible to the long arm of liability attorneys. To hammer home that point, we disabled the stability control, traction control, and anti-lock brakes on the otherwise stock Subaru WRX we used for this test.
–
But how well does it actually work? We took the WRX, our VBOX, and our left foot to the gravel, comparing the nuances of a pendulum turn to a conventionally executed one. Here’s what we learned:
–
–
Vehicle Speed
–
Faster entry and exit speeds characterize the pendulum-turn run. Notice, however, that the low-grip technique is slower than the conventional one for a full two seconds in the middle of the corner. The point at which it becomes slower (001) corresponds to when the throttle is fully open and just before the peak yaw rate (see 013) is achieved. In other words, it’s the point where the car is rotating fastest. The driver sacrifices speed early to get the car pointed in the right direction sooner and exit at a higher velocity.
–
–
Brake-Pedal Position
–
Despite entering the corner 3.5 mph faster using a pendulum turn and left-foot braking, our driver goes to the brake almost 15 feet later in the corner, as he’s confident the car will turn rather than understeer. Notice the overlap of braking and throttle as the pendulum turn is initiated (002, 005). Using the left-foot technique, peak braking is more aggressive (32 percent of the pedal travel versus 16 percent) (003) once the car is turned back to the left. Braking also ends sooner in the left-foot run (004).
–
–
Accelerator-Pedal Position
–
Our driver presses the accelerator at about 2.1 seconds in both runs (006). His enthusiasm for the throttle comes early (007) in the right-foot-only run, however, and results in a lack of commitment. In that run, after reaching almost half-throttle, he backs off the pedal until later in the corner (008), finally ramping it up to 100 percent (009). Y’know, the usual male premature acceleration.
–
–
Steering-Wheel Angle
–
Notice that the left-foot-braking run begins with initial steering input to the right (010). A small flick redirects the momentum from the initial juke to the right to rotate the car further to the left as it enters the corner. Countersteering starts at 1.8 seconds (011), just as the right-foot-braking run’s initial turn-in is beginning (012).
–
- –
- Out to Launch: The Art (and the Data) behind Launching a Car Quickly
- Lightning Lap 2016: The Year’s Fastest Street Cars on America’s Toughest Track
- How Much Does a Donut Spare Tire Limit Performance?
–
–
–
–
–
Yaw Rate
–
By measuring how rapidly a car rotates around its vertical axis, yaw rate illustrates how much quicker the left-foot technique pivots the WRX into the turn than a conventional turn would. See how peak yaw rate comes much earlier in the corner using left-foot braking (013). Maybe the former Van Halen frontman was onto something when he said, “When I drive that slow, you know it’s hard to steer.” Maybe he should have used his left foot more often.
–
Car and Driver BlogCar and Driver Blog
