MoTeC’s Subaru Diff Controller (SDC) is suitable for Subaru WRX and STi vehicles. It is a plug-in replacement for the factory fitted Driver Controlled Centre Diff (DCCD) controller, fitting into the OEM box that is bolted to the steering column underneath the dashboard.
Functionality
The SDC unit is used to adjust the torque split between the front and rear differentials to achieve greater control over handling characteristics such as traction, braking on loose surfaces, turn in response, and understeer on both corner entry and exit.
The centre differential is essentially a limited slip differential with adjustable preload. The SDC works by regulating solenoid current, which is proportional to the preload. When no current is applied (0% lock) the centre differential operates as an 'open diff' with a mechanical torque distribution of 65% rear and 35% front (60% and 40% in some vehicles). With increasing current (increasing percentage lock) the preload increases, requiring more torque difference between front and rear wheels before the centre differential will slip.
There are six selectable control modes: 0% lock, 100% lock and four user-configurable modes. These modes can be selected using the DCCD thumb wheel.