Shift time

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 direct-shift gearbox 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 simple terms, a DSG is two separate manual gearboxes (and clutches), contained within one housing, and working as one unit.It was designed by BorgWarner,and was initially licensed to the Volkswagen Group, with support by IAV GmbH.[citation needed] By using two independent clutches, a DSG can achieve faster shift times (8ms), and eliminates the torque converter of a conventional epicyclic automatic transmission.

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.

Gearbox shift times (Fastest to slowest)

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