Shift time
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 manual transmission|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 [Automatic transmission|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 and 1 - 2 s to perform horizontal gear changes. Shift time is also dependent on gear throws, 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
Example upshift times
Please note that some manufacturers may have different definitions of shift times, this is not a complete list.| Vehicle | Transmission model | Transmission type | Shift time | Notes |
| McLaren 675LT | 7 Speed SSG | Dual-Clutch | 40 | According to MotorTrend Article |
| Lamborghini Aventador | Graziano ISR | Automated manual | 50 | |
| Ferrari 430 Scuderia | Graziano F1 | Automated manual | 60 | |
| Ferrari FXX Evoluzione | Graziano F1 | Automated manual | 60 | |
| Maserati GranTurismo MC Stradale | Maserati MC Race Shift | Automated manual | 60 | With Race mode active |
| BMW M5 (E60) | BMW SMG III | Automated manual | 65-250 | |
| Ferrari FXX | Graziano F1 | Automated manual | 80 | |
| Shelby GT500 | Tremec TR-9070 | Dual-clutch | 80 | |
| Bugatti Veyron | Volkswagen Group DSG | Dual-clutch | 100 | |
| Mercedes-Benz AMG GT-Line | Mercedes-Benz AMG SpeedShift | Dual-clutch | 100 | As little as 100ms, according to MB |
| Lexus LC 500 | Aisin WR10L65 | Hydraulic automatic | 120 | |
| Renault Clio RS 200 EDC Trophy | Renault EDC | Dual-clutch | <120 | With Race mode active |
| Chevrolet Camaro ZL1 | Ford-GM 10L90 | Hydraulic automatic | ~150 | |
| Ferrari Enzo | Graziano F1 | Automated manual | 150 | |
| Nissan GT-R | BorgWarner GR6Z30A | Dual-clutch | 150 | With R Mode active |
| Lexus LFA Nürburgring edition | Aisin SA6 | Automated manual | 150 |