Twin Clutch SST, also known as Twin Clutch Sport Shift Transmission, is a 6-speed automated manual transmission with two clutches and a manual control mode. It is installed on Mitsubishi cars and some models from the French PSA Group. This gearbox was developed by Mitsubishi Motors in cooperation with the company Getrag (now known as Magna PT). It debuted on the Lancer Evolution X in 2008. It is characterised by relatively close gear ratios, which has a positive impact on the vehicle dynamics and is important for high-performance cars.
How the Twin Clutch SST works
The Twin Clutch SST is based on two electro-hydraulic clutches, each of which is responsible for one individual set of gears. While one gear is engaged, the second is already selected and will engage as soon as the corresponding clutch is actuated. Gear shifting is performed smoothly, without interruption of torque flow. This ensures excellent dynamics, reduction of fuel consumption, and allows sportier driving.
In automatic mode, the gearbox control unit decides which gear should be selected depending on readings of various sensors. The driver is able to choose between the driving modes, including Normal and Sport (S-Sport on some versions). If necessary, the driver can switch to manual control. To do this, they slide the gear lever from the “D” position into a special slot and then to the “+” or “-” position, or use the paddle shifters.
Technical characteristics of Twin Clutch SST
|Gearbox code||Number of gears||Max engine capacity, L||Max torque, N·m||Clutch type||Car layout||Production start||Model applications|
|SPS6 (6DCT470)||6||2.2||470||Wet||FWD, AWD||2008||Mitsubishi cX; Mitsubishi Outlander; Citroën C-Crosser; Galant Fortis; Peugeot 4007; Mitsubishi Lancer|
- The damper and springs can break down prematurely. The problem is exacerbated by aggressive driving.
- The transmission is sensitive to soiling. The filter and fluid should be replaced frequently.
- The hydraulic valve body channels and solenoids become clogged with wear products of the friction plates and elements of the damper, which leads to transmission malfunctions.
- The transmission tends to get overheated, so the fluid cooler should be cleaned regularly.
- The sealing cover can be damaged by excessive vibrations, causing a leak in the gearbox casing.