Manual Transmissions & Parts

A manual transmission (also known as a stick shift or standard transmission) is a type of transmission used in automotive applications. Manual transmissions often feature a driver-operated clutch and a movable gear selector, although some do not. more...

Most automobile manual transmissions allow the driver to select any gear at any time, but some, such as those commonly mounted on motorcycles and some types of race cars, only allow the driver to select the next-highest or next-lowest gear ratio. This second type of transmission is sometimes called a sequential manual transmission.

Manual transmissions are characterized by gear ratios which are selectable by engaging pairs of gears inside the transmission. Conversely, automatic transmissions feature clutch packs to select gear ratio. Transmissions which employ clutch packs but allow the driver to manually select the current gear are called semi-automatic transmissions.

Contemporary automotive manual transmissions are generally available with between 4 and 6 forward gears and one reverse gear, although manual transmissions have been built with as few as 2 and as many as 7 gears. Some manuals are referred to by the number of forward gears they offer (e.g., 5-speed) as a way of distinguishing between automatic or other available manual transmissions. In contrast, a 5-speed automatic transmission is referred to as a 5-speed automatic.

Other types of transmission in mainstream automotive use are the automatic transmission, semi-automatic transmission, and the continuously variable transmission.

Manual transmissions come in two basic types: simple unsynchronized systems where gears are spinning freely and their relative speeds must be synchronized by the operator to avoid noisy and damaging "clashing" and "grinding" when trying to mesh the rotating teeth, and synchronized systems that eliminate this necessity while changing gears.

Unsynchronized transmission

The earliest automotive transmissions were entirely mechanical unsynchronized gearing systems. They could be shifted, with multiple gear ratios available to the operator, and even had reverse. But the gears were engaged by sliding mechanisms or simple clutches, which required skills of timing and careful throttle manipulation when shifting, so that the gears would be spinning at roughly the same speed when engaged; otherwise the teeth would refuse to mesh.

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