These days, traditional h-pattern gearboxes are being replaced by paddle-shifters because of the inherent efficiency and fuel economy they offer. While it’s a shame, it’s an understandable move forward. However, it does separate the driver from his machine. Not only is shifting the old-fashioned clutch-and-stick assembly lots of fun, but it gives the driver a visceral connection with the car and it helps reveal the car’s behavior. While shifting seems simple, there are a few instances in which tricks like skipping gears and short-shifting will come in handy. Learning the intricacies of your transmission will save you money, shorten your lap times, and make you sound (and hopefully drive) like someone world-class.
Learning to shift gears all revolves around the idea of accessing the peak, or ideal, power and torque figures at any given moment. These figures occur within a range of revs known as the “power band” and outside of it the engine is either sluggish or inefficient. When we’re dawdling around town in our manual transmission-equipped car, we keep the revs low to save gas. But when we want to accelerate onto the freeway, we have to rev the engine higher as the peak power is typically made towards the top of the rev range.
Maximizing the Engine’s Potential
When we’re on track and efficiency goes out the window, we begin looking at the transmission in a slightly different light. For instance, before we begin braking for an upcoming corner, we have to employ a technique known as “heel-and-toe” to ensure a smooth down-change which will lead to a responsive pickup when it comes time to accelerate out of the upcoming corner. Because we are braking and our engine revs are dropping, we have to focus our attention on selecting the right gear so that we are in the power band when exiting the corner. So, as we’re braking, we depress the clutch, select the appropriate gear, roll the heel of our right food (which is still exerting constant pressure on the brake pedal) onto the throttle to raise the revs by a thousand or so, and release the clutch to engage the gear. This may appear to be a daunting amount of multitasking, but it quickly becomes second nature.
One mistake to avoid when down-changing is shifting too soon. In order to avoid over-revving the engine, since engine revs will naturally increase when a lower gear is selected and the rolling speed remains the same, it is important to spend a good period of time braking and reducing both the road and engine speed before downshifting. This way, you allow the engine to rev up at the right time and avoid it spiking past the red line, which cannot be prevented by the rev-limiter in this instance.
Another problem with downshifting is not matching revs correctly. If the engine has to raise the revs without your heel’s assistance, it exerts a force known as engine braking, which is tough on the driveline and can lock the rear wheels if done too harshly. This is avoided by applying the correct amount of revs while down-changing. Just get that heel over the throttle and don’t worry about too much or too little – usually a small, audible “blip” in conjunction with a smooth release of the clutch is fine.
The complexities of downshifting can be summed up in one word: timing. Get the synchronization of inputs right and there’s little to worry about. On the other hand, up-shifting, while less technical, requires a certain amount of “feel” and improvisation.
If you’ve heard the term “short-shifting,” you’ve heard someone making a reference to the act of shifting well before the end of the power band. This is because, on occasion, it allows for a smoother, faster exit from a corner. Shifting mid-corner is not desirable and can often result in a slide, a drop in revs, or both. In long corners where the driver is applying power gently and keeping steering lock on for a relatively long time, it sometimes helps to shift up prematurely so that when the throttle can be fully applied, the driver won’t have to lift and change gear. In effect, a bit of entry speed is sacrificed by shifting early so that the power can be applied safely and for a longer period of time. If the shift is done before the car is fully loaded up, it should allow for a smooth departure from the corner. This takes a certain amount of feel and familiarity with the breakaway characteristics of your car and your tires, but just remember that shifting is ideally performed when the car is as straight as possible.
For as long as I can remember, there has been a debate about whether or not to downshift sequentially or to skip gears. Shifting sequentially is more commonly used, as it’s easier to measure the amount of blipped-revs necessary, but it also exerts a stabilizing effect on the rear end. I’ve heard of it described as a rudder and can be especially helpful when driving on a wet surface. Skipping gears, on the other hand, will save the clutch some wear-and-tear if executed correctly. There are occasions where skipping gears becomes necessary, like when you lose a gear mid-race and must avoid it while changing down. However, it requires a deft pair of feet. When skipping, synchronizing the release of the clutch and the blipping of the throttle become more important as the change in relative road speeds is greater, and therefore the rev-matching needs to be done almost perfectly. As a rule of thumb, you will need to apply a prodigious blip when skipping gears, but it depends on how closely your gears are stacked together.
When traction is low, it’s important to remember that sometimes, lots of power will not move you forward any faster. You’ll note how rally drivers will occasionally select a higher gear to limit the amount of available torque and therefore, wheelspin. Having slightly less response and power on hand can keep the care more composed and less skittish. Like with short-shifting on a dry track, staying on the power for longer will sometimes prove faster than being at the peak of the power band, but it all depends on the amount of grip available. Learning when to shift and how to control the output of your engine will give you a better understanding of your car and how to best utilize it. When you hear purists bemoaning the h-pattern going extinct, it’s for a good reason! As we’ve seen, learning how to properly shift an h-pattern gearbox will illustrate how minor inputs can effect the behavior of the car and instill a sense of mechanical sympathy. Though what purists moan about has nothing to do with efficiency or the prolonging of gears. It’s the sheer fun of rowing up and down, revving the engine on the down change, and the almost Riverdance-like footwork that goes on during a bit of heel-and-toe. It is the interaction between the car and the driver, which, while measured and explained with rationale, is an emotional process that is hard to let go of.