MoTeC’s Subaru Diff Controllers (SDC, SDC2 and SDC3) are suitable for Subaru WRX and STi vehicles. They are plug-in replacements 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.
It is worth considering the installation of a MoTeC M800 Plug-In ECU in addition to the SDC2 or SDC3 to take advantage of several additional features. Using the RS232 serial communication link, all values from sensors connected to the SDC2 or SDC3 can be logged in the M800 Plug-In ECU, without having to duplicate any of the sensors.
The SDC units are 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 SDCs work 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.
connector(s) fitting directly into the factory wiring
1 x CAN
1 x RS232 (SDC2 and SDC3 only)
- 6 x Selectable control modes:
- 1 x 0% lock mode
- 4 x user-defined modes
- 1 x 100% lock mode
- Control modes can be selected using the DCCD thumbwheel.
- Each mode is configurable with an acceleration table, braking table and desired slip table.
- The percentage lock can be configured using vehicle speed and throttle position. With the MoTeC M800 Plug-In ECU connected, engine efficiency point can be used instead of throttle position. The ECU will calculate and then send the efficiency point to the SDC2 or SDC3. This feature uses the factory wiring loom.
- With the RS232 serial communications configured, the SDC2 or SDC3 can send wheel speeds, lateral G-force, longitudinal G-force, steering position, diff parameter and fault codes to the MoTeC M800 Plug-In ECU without the need for additional sensors.
- The CAN interface optionally transmits the sensor and diagnostic information to a MoTeC Dash Logger.
- Handbrake override.
Different versions of the Subaru SDC are available to suit the following model years.
SDC (MoTeC #14009) - Subaru WRX and STi (models from 2002–2004)
SDC2 (MoTeC #14010) - Subaru WRX and STi (models from 2005–2007)
SDC3 (MoTeC #14015) - Subaru WRX and STi (models from 2008)