Shift time
Encyclopedia
Shift time refers to the time interval between gear
changes in a transmission
during which power
delivery is interrupted. This is usually in reference to motor vehicles but can apply to any gearbox. Reducing shift time is important in performance vehicles or race cars because during shifting the vehicle is rolling without power to the wheels. Shift time in a manual
gearbox is dependent on the driver but in automatic
or semi-automatic
cars the electronic mechanism must be tuned to minimize the time between gears.
One method of drastically reducing shift time is to use a Direct-Shift Gearbox
which has two independent clutch
es that predict the next gear change making the shift time very small. Using a freewheel
may reduce shift time as it may not be necessary to use the clutch. A shift kit
is also intended to reduce the shift time of a manual vehicle.
In a manual transmission
car, shift time for upshifts can be reduced by installing a lighter flywheel
. During an upshift the engine revolutions must fall for the same vehicle speed; lighter flywheel will cause the revolutions to drop faster when the engine is unloaded, leading to shorter shift times.
Gear
A gear is a rotating machine part having cut teeth, or cogs, which mesh with another toothed part in order to transmit torque. Two or more gears working in tandem are called a transmission and can produce a mechanical advantage through a gear ratio and thus may be considered a simple machine....
changes in a transmission
Transmission (mechanics)
A machine consists of a power source and a power transmission system, which provides controlled application of the power. Merriam-Webster defines transmission as: an assembly of parts including the speed-changing gears and the propeller shaft by which the power is transmitted from an engine to a...
during which power
Motive power
In thermodynamics, motive power is an agency, as water or steam, used to impart motion. Generally, motive power is defined as a natural agent, as water, steam, wind, electricity, etc., used to impart motion to machinery; a motor; a mover. The term may also define something, as a locomotive or a...
delivery is interrupted. This is usually in reference to motor vehicles but can apply to any gearbox. Reducing shift time is important in performance vehicles or race cars because during shifting the vehicle is rolling without power to the wheels. Shift time in a manual
Manual transmission
A manual transmission, also known as a manual gearbox or standard transmission is a type of transmission used in motor vehicle applications...
gearbox is dependent on the driver but in automatic
Automatic transmission
An automatic transmission is one type of motor vehicle transmission that can automatically change gear ratios as the vehicle moves, freeing the driver from having to shift gears manually...
or semi-automatic
Semi-automatic transmission
A semi-automatic transmission is an automobile transmission that does not change gears automatically, but rather facilitates manual gear changes by dispensing with the need to press...
cars the electronic mechanism must be tuned to minimize the time between gears.
One method of drastically reducing shift time is to use a Direct-Shift Gearbox
Direct-Shift Gearbox
The Direct-Shift Gearbox , commonly abbreviated to DSG, is an electronically controlled dual clutch multiple-shaft manual gearbox, in a transaxle design - without a conventional clutch pedal, and with full automatic, or semi-manual control...
which has two independent clutch
Clutch
A clutch is a mechanical device which provides for the transmission of power from one component to another...
es that predict the next gear change making the shift time very small. Using a freewheel
Freewheel
thumb|Freewheel mechanismIn 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...
may reduce shift time as it may not be necessary to use the clutch. A shift kit
Shift kit
A Shift kit is an aftermarket component for automobiles to improve how well the car shifts between gears. Kits are mode for both automatic and manual transmissions.-Manual transmission kit:...
is also intended to reduce the shift time of a manual vehicle.
In a manual transmission
Manual transmission
A manual transmission, also known as a manual gearbox or standard transmission is a type of transmission used in motor vehicle applications...
car, shift time for upshifts can be reduced by installing a lighter flywheel
Flywheel
A flywheel is a rotating mechanical device that is used to store rotational energy. Flywheels have a significant moment of inertia, and thus resist changes in rotational speed. The amount of energy stored in a flywheel is proportional to the square of its rotational speed...
. During an upshift the engine revolutions must fall for the same vehicle speed; lighter flywheel will cause the revolutions to drop faster when the engine is unloaded, leading to shorter shift times.
Shift times
- A long shift time (for a VW automatic transmission to trigger an error code) is considered anything over 625 msMillisecondA millisecond is a thousandth of a second.10 milliseconds are called a centisecond....
- The average manual car driver: 500 ms - 1 s
- Aston Martin Vanquish: 250 ms
- Ferrari 575M: 220 ms
- BMW M3 E36 with SMG I: 220 ms
- Audi TTAudi TTThe Audi TT is a two-door sports car manufactured by the German automaker and Volkswagen Group subsidiary Audi since 1998.The Audi TT has been produced in two generations. Both generations have been available in two car body styles; as a 2+2 Coupé, or two-seater Roadster...
Quattro 3.2 (Direct ShiftDirect-Shift GearboxThe Direct-Shift Gearbox , commonly abbreviated to DSG, is an electronically controlled dual clutch multiple-shaft manual gearbox, in a transaxle design - without a conventional clutch pedal, and with full automatic, or semi-manual control...
): 200 ms - Nissan GT-RNissan GT-RThe Nissan GT-R is a sports car produced by Nissan released in Japan on December 6, 2007, the United States on July 4, 2008, and the rest of the world in March 2009.-History:...
: 200ms - Lexus LFALexus LFAThe Lexus LFA is a 2-seat exotic sports coupe produced by Lexus as a concept car, "halo" vehicle, racing prototype, and production model. It is the second model in the F marque line of performance vehicles from Lexus, following the IS F...
: 200 ms - Ferrari 360 Challenge Stradale & Ferrari F430Ferrari F430The Ferrari F430 is a sports car that was produced by the Italian automaker Ferrari from 2004 to 2009, as a successor to the 360. It debuted at the 2004 Paris Motor Show...
: 150 ms - Enzo FerrariEnzo Ferrari (car)The Enzo Ferrari is a 12 cylinder mid-engine berlinetta named after the company's founder, Enzo Ferrari. It was built in 2002 using Formula One technology, such as a carbon-fibre body, F1-style electrohydraulic shift transmission, and Carbon fibre-reinforced Silicon Carbide ceramic composite...
: 150 ms - Ferrari FXXFerrari FXXThe Ferrari FXX is a high performance race car built by automobile manufacturer Ferrari in Maranello, Italy. The FXX is based on the street-legal Enzo. Production of the FXX began in 2005.- Overview :...
: Under 100 ms - BMW M3 E46 with SMG II: 80 ms
- Ferrari 430 Scuderia & FXX EvoluzioneFerrari FXXThe Ferrari FXX is a high performance race car built by automobile manufacturer Ferrari in Maranello, Italy. The FXX is based on the street-legal Enzo. Production of the FXX began in 2005.- Overview :...
: 60 ms - Bugatti VeyronBugatti VeyronThe Bugatti Veyron EB 16.4 is a mid-engined grand touring car. The Super Sport version is the fastest road-legal production car in the world, with a top speed of . The original version has a top speed of...
(Direct ShiftDirect-Shift GearboxThe Direct-Shift Gearbox , commonly abbreviated to DSG, is an electronically controlled dual clutch multiple-shaft manual gearbox, in a transaxle design - without a conventional clutch pedal, and with full automatic, or semi-manual control...
): 8 ms - Golf GTI (DSGDSGDSG may stand for:* Direct-Shift Gearbox, a type of automotive gearbox from Volkswagen Group* DOCSIS Set-top Gateway, a technical specification* DSG International , Dixons Stores Group, a European retailer...
) : 8 ms - Alfa Romeo MitoAlfa Romeo MiToThe Alfa Romeo MiTo is a three door sporty supermini officially introduced on June 19, 2008, at Castello Sforzesco in Milan, with an international introduction at the British Motor Show in 2008. The car was available in all Alfa's major markets in stages from July...
& Alfa Romeo Giulietta (2010) Dual Dry Clutch TransmissionDual clutch transmissionA dual clutch transmission, commonly abbreviated to DCT , is a differing type of semi-automatic or automated manual automotive transmission. It utilises two separate clutches for odd and even gear sets...
TCT: 8 ms