Go Kart Transmissions
A closer look at manuals and automatics
Because there are different types of go karts, it makes sense that there are also different types of transmissions available. Most types of recreational karts are built with fixed gearing, which determines how fast the machine can travel. Most of these models can reach about 60 mph in sprint karts and just over 100 mph in the case of Enduro karts.
Years ago, most go karts were the non-shifting direct-drive variety. However, centrifugal clutch models were later introduced for higher level classes.In a direct drive kart, the engine drives the rear axle directly through a chain. In a centrifugal clutch machine, the rear axle isn't driven by the chain until the engine has reached a specific RPM; this is known as the stall speed. Direct drive models need to be push started, while clutch karts use a separate starter. The first clutch karts were dry; the oil bath clutch became popular later on. The oil bath (or slipper clutch as it is sometimes known) enables high RPM engines to rev higher on the power curve, at low speeds. When the clutch is engaged, it results in quick acceleration.
Most serious kart racers use shifter karts. These have a six-speed manual transmission and a clutch which enables the driver to get the most power out of the engine by shifting gears at the right time. Some of these gearboxes are operated with wheel-mounted paddles. You may find yourself reaching speeds of up to 160 mph in one of these. These karts use a sequential gear box, which enables the driver to keep the engine in optimum RPM ranges by knowing when to shift the six manual gears. Shifter karts are more complex and costly than other models because of the gear shifter and gear box. These karts usually run as a separate racing division. However, they are also used in sprint and road racing.
The torque converter is one other type of go kart transmission. This is usually used in recreational karts. However, this system can also be used in racing karts. A torque converter works in situations where there is a belt attached to a pair of pulleys. When the engine's RPM increases, the belt shifts higher and higher in one of the pulley's grooves. This process eventually causes the gear ratio to become bigger.