Left-foot braking

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Left-foot braking is the technique of using the left foot to operate the brake pedal in an automobile, leaving the right foot dedicated to the throttle pedal. [1] It contrasts with the practice of using the left foot to operate the clutch pedal, leaving the right foot to share the duties of controlling both brake and gas pedals.

Contents

At its most basic purpose, left-foot braking can be used to decrease the time spent moving the right foot between the brake and throttle pedals, and can also be used to control load transfer. [1]

It is most commonly used in auto racing (simultaneous gas and brake keeps turbo pressure and reduces turbo lag).

Racing and rallying

Karts, many open-wheelers, and cars that are equipped with automatic transmissions, or semi-automatic transmissions with paddle-shifters (as used in motorsports such as Formula One) have no foot-operated clutch, and allow, or sometimes even require the driver to use their left foot to brake.

One common race situation that requires left-foot braking is when a racer is cornering under power. If the driver does not want to lift off the throttle, potentially causing trailing-throttle oversteer, left-foot braking can induce a mild oversteer situation, and help the car "tuck", or turn-in better. Mild left-foot braking can also help reduce understeer. [2]

In rallying left-foot braking is very beneficial, especially to front-wheel drive vehicles. [3] [4] It is closely related to the handbrake turn, but involves locking the rear wheels using the foot brake (retarding actually, to reduce traction, rarely fully locking best considered a misapplication), which is set up to apply a significant pressure bias to the rear brakes. The vehicle is balanced using engine power by use of the gas pedal, operated by the right foot. The left foot is thus brought into play to operate the brake. It is not as necessary to use this technique with rear-wheel drive and four-wheel drive rally vehicles because they can be easily turned rapidly by using excess power to the wheels and the use of opposite lock steering, however the technique is still beneficial when the driver needs to decelerate and slide at the same time. In rear wheel drive, left foot braking can be used when the car is at opposite lock and about to spin. Using throttle and brake will lock the front tires but not the rears, thus giving the rears more traction and bringing the front end around.

Finnish rally legend Flying Finn Rauno Aaltonen used left-foot braking as a driving style in rallying when he competed for Saab in the 1950s. [5]

In restrictor plate NASCAR events, drivers were known to left-foot-brake at times, particularly in heavy traffic situations. Rather than lift off the throttle, which could lose considerable power and speed (due to the restrictor plates), a mild tap of the brakes while the right foot was still planted flat on the gas, could help avoid contact and bump drafting.

This technique should not be confused with heel-and-toe shifting, which is another driving technique.

Switch-foot braking

A left-foot braking technique where the driver will complete the heel-and-toe downshift using standard right-foot braking at which time they will switch to left-foot braking. This is most often used by drivers wishing to employ left-foot braking, but that must still use the left foot to operate the clutch. [6]

Throttle-braking

A braking technique where the driver will combine the use of left-foot braking with throttle to dynamically control brake bias and remove engine braking. In a rear wheel drive vehicle, greater throttle usage while braking will counteract the rear braking force and move the brake bias forward. [6]

Road use

Many commentators advise against the use of left-foot braking while driving on public roads. Critics of the technique suggest that it can cause confusion when switching to or from a vehicle with a manual transmission, [7] and that it is difficult to achieve the necessary sensitivity to brake smoothly when one's left foot is accustomed to operating a clutch pedal. [8] Most of the arguments are based on the difficulty of switching from automatic to manual cars, and do not apply to people who only drive automatic cars. [7] [8]

However, some commentators do recommend left-foot braking as routine practice when driving vehicles fitted with an automatic transmission, when maneuvering at low speeds. [9]

Proponents of the technique note that in low-speed maneuvers, a driver of a vehicle with a manual transmission will usually keep a foot poised over the clutch pedal, ready to disengage power when the vehicle nears an obstacle. This means that disengagement is also possible in the event of malfunction such as an engine surge. However, the absence of a clutch pedal on a vehicle with automatic transmission means that there is no such safety override, unless the driver has a foot poised over the brake pedal. [9]

Related Research Articles

Heel-and-toe shifting is an advanced driving technique used mostly in performance driving with a manual gearbox, although some drivers use it on the road in everyday conditions in the interest of effectiveness. It involves operating the throttle and brake pedals simultaneously with the right foot, while facilitating normal activation of the clutch with the left foot. It is used when braking and downshifting simultaneously, and allows the driver to "blip" the throttle to raise the engine speed and smoothly engage the lower gear.

<span class="mw-page-title-main">Opposite lock</span> Driving terminology

Opposite lock, also commonly known as countersteer, is a colloquial term used to mean the steering associated with the deliberate use of oversteer to turn a vehicle rapidly without losing momentum. It is typified by the classic rallying style of rear-wheel drive cars, where a car travels around a bend with a large drift angle. The terms "opposite lock" and "counter-steering" refer to the position of the steering wheel during the maneuver, which is turned in the opposite direction to that of the bend.

<span class="mw-page-title-main">Handbrake turn</span> Driving technique

The handbrake turn is a driving technique used to deliberately slide a car sideways, either for the purpose of quickly negotiating a very tight bend, or for turning around well within the vehicle's own turning diameter.

<span class="mw-page-title-main">Automatic transmission</span> Type of motor vehicle transmission that automatically changes gear ratio as the vehicle moves

An automatic transmission is a multi-speed transmission used in motor vehicles that does not require any input from the driver to change forward gears under normal driving conditions. Vehicles with internal combustion engines, unlike electric vehicles, require the engine to operate in a narrow range of rates of rotation, requiring a gearbox, operated manually or automatically, to drive the wheels over a wide range of speeds.

A traction control system (TCS), is typically a secondary function of the electronic stability control (ESC) on production motor vehicles, designed to prevent loss of traction of the driven road wheels. TCS is activated when throttle input and engine power and torque transfer are mismatched to the road surface conditions.

<span class="mw-page-title-main">Manual transmission</span> Motor vehicle manual gearbox; stick shift

A manual transmission (MT), also known as manual gearbox, standard transmission, or stick shift, is a multi-speed motor vehicle transmission system, where gear changes require the driver to manually select the gears by operating a gear stick and clutch.

<span class="mw-page-title-main">Freewheel</span> Mechanism which disconnects a driveshaft from a faster-rotating driven shaft

In mechanical or automotive engineering, a freewheel or overrunning clutch is a device in a transmission that disengages the driveshaft from the driven shaft when the driven shaft rotates faster than the driveshaft. An overdrive is sometimes mistakenly called a freewheel, but is otherwise unrelated.

<span class="mw-page-title-main">Direct-shift gearbox</span> Type of dual-clutch transmission

A direct-shift gearbox is an electronically controlled, dual-clutch, multiple-shaft, automatic gearbox, in either a transaxle or traditional transmission layout, with automated clutch operation, and with fully-automatic or semi-manual gear selection. The first dual-clutch transmissions were derived from Porsche in-house development for the Porsche 962 in the 1980s.

<span class="mw-page-title-main">Burnout (vehicle)</span> Practice of spinning wheels while keeping vehicle stationary

A burnout is the practice of keeping a vehicle stationary and spinning its wheels, the resultant friction causing the tires to heat up and smoke.

<span class="mw-page-title-main">Parking brake</span> Secondary automotive braking system

In road vehicles, the parking brake, also known as a handbrake or emergency brake (e-brake), is a mechanism used to keep the vehicle securely motionless when parked. Parking brakes often consist of a pulling mechanism attached to a cable which is connected to two wheel brakes. In most vehicles, the parking brake operates only on the rear wheels, which have reduced traction while braking. The mechanism may be a hand-operated lever, a straight pull handle located near the steering column, or a foot-operated pedal located with the other pedals.

A transmission control unit (TCU), also known as a transmission control module (TCM), or a gearbox control unit (GCU), is a type of automotive ECU that is used to control electronic automatic transmissions. Similar systems are used in conjunction with various semi-automatic transmissions, purely for clutch automation and actuation. A TCU in a modern automatic transmission generally uses sensors from the vehicle, as well as data provided by the engine control unit (ECU), to calculate how and when to change gears in the vehicle for optimum performance, fuel economy and shift quality.

Lift-off oversteer is a form of sudden oversteer. While cornering, a driver who closes the throttle, usually at a high speed, can cause such sudden deceleration that the vertical load on the tires shifts from rear to front, in a process called load transfer. This decrease in vertical load on the rear tires in turn decreases their traction by lowering their lateral force, making the vehicle steer more tightly into the turn. In other words, easing off the accelerator in a fast turn can cause a car's rear tires to loosen their grip so much that the driver loses control and drifts outwards, even leaving the road tailfirst.

<span class="mw-page-title-main">Scandinavian flick</span> Driving technique

The Scandinavian flick, Finnish flick, pendulum turn, or Scandi flick is a technique used predominantly in ice racing and rallying. The technique induces oversteer using weight transfer to carry a vehicle through a turn while simultaneously reducing speed.

In an automobile, the dead pedal, often also called a footrest, is typically a non-moving piece of rubber or metal that the driver is supposed to rest his or her left foot on when driving. Although the dead pedal serves no function in the car, many car manufacturers opt to implement it because it provides a number of benefits to the driver. In manual transmission cars, the dead pedal is designed to promote a smoother actuation of the clutch by keeping the driver's foot in the same plane as the pedal. Automatic transmission cars can also benefit from the dead pedal because it prevents fatigue by offering a stable inclined surface on which the driver can place their foot. Even if a car does not have a dead pedal installed, there are a variety of aftermarket accessories that can be installed.

Clutch control refers to the act of controlling the speed of a vehicle with a manual transmission by partially engaging the clutch plate, using the clutch pedal instead of the accelerator pedal. The purpose of a clutch is in part to allow such control; in particular, a clutch provides transfer of torque between shafts spinning at different speeds. In the extreme, clutch control is used in performance driving, such as starting from a dead stop with the engine producing maximum torque at high RPM.

A wheelspin occurs when the force delivered to the tire tread exceeds that of available tread-to-surface friction and one or more tires lose traction. This leads the wheels to "spin" and causes the driver to lose control over the tires that no longer have grip on the road surface. Wheelspin can also be done intentionally such as in drifting or doing a burnout.

All Wheel Control (AWC) is the brand name of a four-wheel drive (4WD) system developed by Mitsubishi Motors. The system was first incorporated in the 2001 Lancer Evolution VII. Subsequent developments have led to S-AWC (Super All Wheel Control), developed specifically for the new 2007 Lancer Evolution. The system is referred by the company as its unique 4-wheel drive technology umbrella, cultivated through its motor sports activities and long history in rallying spanning almost half a century.

<span class="mw-page-title-main">Line lock</span> Vehicle braking technology

A line lock is a device that allows the front brakes to lock independently of the rear brakes via a switch. The device is an electric solenoid that controls a valve which allows the brakes to be controlled individually. This allows the front brakes to be locked and the rear brakes to be open, and allows the driver to spin the rear wheels without wasting the rear brakes. This method is referred to as line lock and is popular among enthusiasts who like to do burnouts.

<span class="mw-page-title-main">Motorcycle transmission</span> Transmission for motorcycle applications

A motorcycle transmission is a transmission created specifically for motorcycle applications. They may also be found in use on other light vehicles such as motor tricycles and quadbikes, go-karts, offroad buggies, auto rickshaws, mowers, and other utility vehicles, microcars, and even some superlight racing cars.

<span class="mw-page-title-main">Car controls</span> Car parts used to control the vehicle

Car controls are the components in automobiles and other powered road vehicles, such as trucks and buses, used for driving and parking.

References

  1. 1 2 "Team O'Neil Rally School & Car Control Center | Press". Team-oneil.com. Archived from the original on 2009-04-16. Retrieved 2009-05-04.
  2. "Left Foot Braking In Front Wheel Drive, Rally Racing News". Rallyracingnews.com. Retrieved 2009-05-04.
  3. Dave Coleman. "We join the reigning champion team...and drive the junior car". sportcompactcarweb.com. Archived from the original on 2006-11-16. Retrieved 2007-10-10.
  4. "How to left foot brake" (PDF) (2). Rally Talk. February 2005: 5. Archived from the original (PDF) on 2007-10-07. Retrieved 2007-10-10.{{cite journal}}: Cite journal requires |journal= (help)
  5. "Driving Legends". theitalianjob.com. Retrieved 2009-10-25.
  6. 1 2 "Racing and motorsport Terms Glossary". Paradigm Shift Driver Development. Retrieved 2016-08-04.
  7. 1 2 "Frequently asked question: Why can't I use the left foot for braking in an automatic car?". driving-school.com.au. Archived from the original on 2007-04-29. Retrieved 2007-10-10. (from internet archive)
  8. 1 2 "Ask Ripley". The Daily Telegraph. May 2001. Retrieved 2007-10-10. It is true that some drivers with automatic gearboxes use left-foot braking to good effect but, as a general rule, it is difficult to achieve the necessary sensitivity to brake smoothly when your left foot is used to operating a clutch pedal.[ dead link ]
  9. 1 2 "Driving automatics safely: Why do you repeatedly advocate left foot braking of automatic cars?". HonestJohn.co.uk. Archived from the original on 2010-03-05. Retrieved 2007-10-11.

Bibliography