Currie TwinTrac® Helical-gear limited-slip differential (LSD) is the modern replacement for the classic clutch-style Posi. Under normal driving conditions, the TwinTrac operates like an open differential, allowing the wheels to spin at different speeds to negotiate turns smoothly. However, when accelerating, if a tire begins to lose traction, the helical-gears inside the TwinTrac automatically engage, applying power to both rear tires and maximize traction. When the acceleration (torque) lessens, the differential resumes regular operation. The TwinTrac is maintenance-free and will maintain its high torque bias for the unit's life, as it contains no clutches or springs that can wear-out.
Gear Oil Recommendations
- For all 9-inch applications, Currie recommends 85W-140 weight GL6 rated petroleum-based gear oil
- Synthetic oils are not recommended for 9-inch gears or the TwinTrac limited-slip differential
- Friction modifiers should not be used, as they will decrease differential bias and negatively impact performance
