Shift time refers to the time interval between gear changes in a transmission. This interval is the time in which power delivery is transferred to the next selected gear, and engine speed is reduced or increased to synchronize the speed of the next gear. Shift time is usually in reference to motor vehicles, but can apply to any gearbox. Shift time is measured by the time it takes for the engine rpm to synchronize with the next gear input speed target. This is illustrated by ZF, describing the 100-300 millisecond shifts of their DCT transmissions.
Reducing shift time is important in performance and racing vehicles because upshifting generally interrupts power delivery to the wheels. Shift time in a manual gearbox is dependent on the driver, but in automatic or automated manual cars, the electronic or hydraulic control system must be calibrated and tuned to execute fast gear changes. Historically, a dual-clutch transmission shifts faster than a standard hydraulic automatic transmission with a torque converter or a single-clutch automated manual transmission. This is possible because the DCT can pre-select the next gear and transfer torque from one clutch to the next clutch with the pre-selected next gear, thus reducing shift times. Standard planetary automatic transmissions have caught up to DCT transmission shift times by also utilizing clutch to clutch shifts. For older transmissions, 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.
With a manual transmission, upshift time can be reduced by installing a lighter flywheel. During an upshift, the engine speed must decrease to synchronize with a higher gear; a lighter flywheel will allow the engine speed to drop more quickly, leading to shorter shift times.
Shift times A long shift time is considered anything over 625 milliseconds. The average manual car driver takes between 500 ms and 1 s to perform vertical gear changes (i.e. 1st-2nd, 3rd-4th, 5th-6th) and 1 - 2 s to perform horizontal gear changes (i.e. 2nd-3rd, 4th-5th). Shift time is also dependent on gear throws (distance between gears), ease of movement, ergonomics of the gear stick, and gearbox condition. For reference, the time it takes for a human to blink can be as quick as 100ms (.1 seconds)
Example upshift times Please note that some manufacturers may have different definitions of shift times, this is not a complete list. VehicleTransmission modelTransmission typeShift time (ms)NotesMcLaren 675LT7 Speed SSGDual-Clutch40According to MotorTrend ArticleLamborghini AventadorGraziano ISRAutomated manual50Ferrari 430 ScuderiaGraziano F1Automated manual60Ferrari FXX EvoluzioneGraziano F1Automated manual60Maserati GranTurismo MC StradaleMaserati MC Race ShiftAutomated manual60With Race mode activeBMW M5 (E60)BMW SMG IIIAutomated manual65-250Ferrari FXXGraziano F1Automated manual80Shelby GT500 (3rd generation)Tremec TR-9070Dual-clutch80Bugatti VeyronVolkswagen Group DSGDual-clutch100Mercedes-Benz AMG GT-LineMercedes-Benz AMG SpeedShiftDual-clutch100As little as 100ms, according to MBLexus LC 500Aisin WR10L65Hydraulic automatic120Renault Clio RS 200 EDC Trophy (4th generation)Renault EDCDual-clutch<120With Race mode activeChevrolet Camaro ZL1 (6th generation)Ford-GM 10L90Hydraulic automatic~150Ferrari EnzoGraziano F1Automated manual150Nissan GT-RBorgWarner GR6Z30ADual-clutch150With R Mode activeLexus LFA Nürburgring editionAisin SA6Automated manual150
See also Powershifting Shift kit
References