Subaru Impreza WRX STI Drivetrain Upgrade Components Rear Limited Slip Differential (R180) and DCCD (Driver's Control Center Differential) How Does Subaru DCCD Work? The Driver's Control Centre Differential (DCCD) allows the center differential locking of the WRX STI to be dialed in and adjust its handling. It adjusts both an electromagnetic multi-plate transfer clutch and mechanical locking of a Limited Slip Differential (LSD) to distribute torque to the front and rear wheels. Auto Mode identifies the ideal power distribution for changing conditions, whilst Auto [+] keeps more power up front for increased traction. Auto [-] transfers more power to the rear for tighter cornering, and the six-step Manual Mode locks in the driver's favorite handling characteristics. To operate as designed, clutch plates inside the DCCD unit must be capable of transferring the torque, especially when the engine is modified to higher power. Therefore, Racing Diffs Ltd developed and tested performance upgrade plates capable of transferring 1000+ HP. The kit is a direct replacement for OEM plates, so no modifications are required. Rear Limited Slip Differential - R180 LSD With this kit, you won't just restore the LSD performance, you will upgrade it significantly. Our clutch plates are Molybdenum-Ceramics coated, which is far superior to any factory metal plates. There is no possibility of metal shavings as with metal plates. Operating temperature is decreased by 15%, making the diff more durable in severe conditions and high horsepower applications. Highly recommended for everybody who visits the track regularly! Fits all OEM Clutch-type R180 Limited slip differentials! Racing Diffs recommends Motul Gear Competition 75w 140 oil for all products. OEM Part Numbers: ST3900055040 ST3900055020 390004S020