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by Dhruv Behl
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Welcome to the second edition in our series of driving tips. I hope you found last month’s tips easy to implement and valuable to use.
As mentioned previously, these ‘driving cues’ are fairly straightforward – their main aim is to increase your awareness behind the wheel and emphasize the importance of the physical act of driving, which, if performed correctly, is an art in itself. This time we’ll cover braking – an act regularly performed but never really considered.
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Braking
Most of us have never felt the true force of modern braking systems. In an emergency stop, you’re liable to experience more g-forces than at any other point in your road cars performance envelope. The reason we never use our cars true braking potential is because in a panic stop we tend to stand on the brake pedal and lock the front wheels – this reduces braking efficiency and increases stopping distances. It’s estimated that locking the front wheels (essentially the point at which the front tires begin to skid) increases stopping distances by upto 30%. Lets assume, if braking is performed correctly, an average car on our roads can stop from 100 km/h to 0 in 165 feet. If you jam the brake pedal and lock the front wheels, effectively you increase 50 feet to this stopping distance.
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There's a directly inverse relationship between the steering wheel and the accelerator pedal - more steering lock (the amount the steering is turned) equals less acceleration and vice-versa |
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So the next time you see long tire marks on the road followed by shards of broken headlight glass, you’ll know two things, one, the car didn’t have ABS (which we’ll get to later), and secondly, the driver could, in all probability, have stopped a lot sooner. The other disadvantage of locking the front wheels is that it reduces maneuverability. Once the front wheels are locked, it means that you can’t steer away from whatever it is you’re trying not to hit.
The ideal way to use the brakes is to be positive on the brake pedal, which is to say be forceful, especially initially, but with a measured approach, and squeeze hard. This allows brake pressure to build progressively and will ensure that the front wheels lock at the last possible moment. Maximum braking efficiency is achieved right at the point of lock up. To achieve this level of braking manually requires an attuned driver with a deft foot. This is referred to as brake modulation – the driver modulates brake pressure by adjusting the pressure of his or her foot on the brake pedal maintaining maximum braking efficiency without locking up the wheels.
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Tires are the single most imporatant safety and performance factor in your car. The contact patch of a cars tire is the only tangible connection of a car to the road |
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If this sounds complicated, like everything else, its not. It just requires some practice and presence of mind. The natural reaction in a panic stop is to stand on the brakes – this doesn’t allow brake pressure to build progressively and locks the front wheels, which in turn reduces braking efficiency and leads to longer stopping distances.
The beauty of ABS is that a computer chip with sensors at all four wheels does all this for you while allowing you to steer at the same time – this means you can also attempt to drive around whatever it is you’re trying not to hit. You know ABS is working when you feel the brake pedal pulsating under your foot as you apply the brakes fully.
There’s one very simple reason why you can’t lock your front wheels and steer at the same time – it’s called the 100% rule. Again, this may seem straight-forward enough, but a tire, like anything else, can only do a 100% of one thing at a time. Let me explain, if a tire is braking at 100% of its ability, there’s no potential left for cornering or steering. Hence, the need to release brake pressure in order to steer while braking.
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As an aside, perhaps the most underrated performance and safety factor in a car are its tires. The contact patch of a cars tire is the only tangible connection of a car to the road. No matter how good the car, if you’re driving on worn tires, it completely negates the effect of how well the car inherently handles or drives. Theoretically, a Civic with new high performance tires could perform better than a Porsche with completely worn tires (anyone with even a hint of petrol in their veins would still prefer the latter though).
Accelerating
Coming out of a corner or a turn, there’s a delicate balance between the amount of acceleration and steering lock (the amount the steering is turned) that can be applied while staying within the 100% rule. For any given amount of steering lock, there’s only a certain level of acceleration that can be applied before you begin to exceed the cornering limits of a car and its tires. Once again, the 100% rule can be altered to state: if you’re cornering at 100% of a tires ability, there’s no room left for acceleration. Alternatively, as you exit a corner and straighten the steering wheel, this progressively increases the scope for acceleration. Essentially, there is an inverse relationship between the steering wheel and the accelerator pedal, more steering equals less power and vice-versa – the angle of steering lock determines the level of acceleration.
While the beauty of driving a racecar to the limits of its cornering ability is finding and maintaining this ever-changing balance, this relationship is easier to sustain on the road. It’s just a question of being aware of what the car and driver are capabable of.
Until next time, buckle up and drive safe |
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