Rev matching is a technique used to prevent unnecessary weight transfer during down-changes in a manual transmission car. For a demonstration of why this concept is useful, select third gear and accelerate to about 3000rpm, then quickly select second and release the clutch fairly rapidly. You'll notice a large forward weight transfer as the engine speed is forced to increase. This can also cause the driving wheels to lock in extreme situations. |
Rev matching will make you a much smoother driver when changing down through the gears, a skill which is useful for the track and can lead to faster lap times. This technique is performed by depressing the clutch, selecting the required lower gear, increasing the throttle, and then releasing the clutch smoothly. You'll need more revs if changing from forth to second that from fourth to third. With practice, this can result in very rapid and very smooth changes, and is almost essential if driving on the track. Rev matching can also be performed while braking, this is known as heel and toe. When you first start to learn this technique, you might find it hard to predict the amount of revs you'll need for each gear, but remember any increase in revs is better than none.
Smooth driving is most important when driving near the limits of your car. When you're taking a tight corner at high speed, the slightest press of the brake or accelerator pedal is likely to result in loss of traction. Graphs 5 and 6 consider the grip demands on a car during the process of cornering on the track. In Graph 5, the driver has separated out the acceleration, braking and steering elements of the corner, which won't yield the best lap times but will increase safety.
This shows a driver who is combining steering with both the braking and acceleration elements of the corner in an attempt to gain better lap times. Steering while braking into a corner is known as trail braking and is an advanced Smooth driving technique , however accelerating at the latter stages of the corner is more commonly used. Great care should be taken when performing these actions, as the combined demands of the lateral and longitudinal forces on the tyres is much more likely to exceed the limits of Smooth driving grip (the yellow dots below).
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