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 or hydraulic mechanism must be tuned to minimize the time between gears.
One method of drastically reducing shift time is to use a dual-clutch transmission which has two independent clutches 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 speed must fall for the same vehicle speed; a lighter flywheel will allow the engine speed to drop more quickly when it is unloaded leading to shorter shift times.
- A long shift time is considered anything over 625 ms
- The average manual car driver: 500 ms - 1 s (vertical gear changes e.g. 1st-2nd, 3rd-4th, 5th-6th): 1s - 2s horizontal gear changes (2nd - 3rd, 4th - 5th, 6th - 7th). As well shift times can change depending on gear throws (distance between gears), its easement of movement, ergonomics of lever and age of gearbox.
Gearbox shift times (Fastest to slowest)
- Bugatti Veyron (DSG): 8 ms
- AUDI (DSG)(Also S tronic): 8 ms[better source needed]
- Volkswagen (DSG)(Also S tronic): 8 ms[better source needed]
- Alfa Romeo Mito & Alfa Romeo Giulietta (2010) Dual Dry Clutch Transmission TCT: 8 ms
- WOT BOX [Single clutch 6 Speed gearbox]: 45ms
- Lamborghini Aventador LP 700-4 [Single clutch ISR gearbox]: 50ms
- Ferrari 430 Scuderia: 60 ms
- Maserati GranTurismo MC Stradale 2016: 60ms
- BMW M5 E60 with SMG III: 250 - 65 ms
- BMW M3 E46 with SMG II: 80 ms
- BMW M3 E92 with M-DCT: 80 ms
- Ferrari FXX: 100 ms
- Drag car: 100 ms
- Maserati GranTurismo S Cambiocorsa: 100 ms
- Mercedes-Benz SLS AMG: 100 ms
- Automatic/semi-automatic transmission: 100 ms
- Clio RS EDC 200: 150 ms (race mode)
- Enzo Ferrari: 150 ms
- Nissan GT-R: 150 ms (R Mode)
- FXX Evoluzione: 160 ms
- Lexus LFA: 200 ms
- Chevrolet Camaro ZL1: 2 ms
- Aston Martin Vanquish: 250 ms
- The fastest (Race gearbox) manual: 250 ms
- Ferrari 575M: 280 ms
- Lamborghini Performante DCT LDF: 290 ms
Artificially delayed shifts
The US version of the 2016 Mercedes CLA 250 engine management electronics artificially delays gearshifts, especially in cold weather. The shift time is still short -- only the time between operating the gear-shift paddles and executing the shift has been artificially set to a nonzero value. All operations of the gear-shift paddles are remembered and executed when their time delay expires. Thus it is possible to schedule multiple gear shifts before the first gear shift is being executed.
- "Tech Tips: Understanding TAP". Automotive Service Association. Archived from the original on 2006-10-03. Retrieved 2006-07-29.
- "Alfa Romeo UK". Archived from the original on 2011-07-12.
- "Ferrari Factory Site".
- "Volkswagen makes way for DSG". Paul Tan. Retrieved 2006-08-11.
- "Ferrari FXX Breaks Cover". Piston Heads. Retrieved 2006-09-23.
- "New Clio R.S. 200 EDC: 'à la carte' sports performance". Renaultsport. Retrieved 2014-03-09.
- "2012 Chevrolet Camaro ZL1 - Staged Up Shifts". SupercarHall. Retrieved 2012-02-23.