Cusco LSD RS1.5WAY (1 & 1.5) Front For GC8 GDA Impreza BR9 BM9

The Cusco Type RS 1.5-Way Limited Slip Differential offers the perfect middle ground between aggressive performance and refined handling, making it a favorite among serious enthusiasts and competitive drivers alike. This LSD is designed to fully lock under acceleration, just like the 1-Way, but unlike the 1-Way, it also partially engages under deceleration. This dual behavior adds braking stability and rear-end control, which is especially useful in high-speed entries, chicanes, or heel-toe downshifting zones.

What separates the 1.5-Way from both the 1-Way and 2-Way is its ability to provide deceleration locking only when needed — avoiding the full-on engagement of a 2-Way while still offering more control than the freewheeling nature of a 1-Way. It strikes a balance that improves turn-in response, maintains stability under trail braking, and reduces mid-corner understeer. This makes the 1.5-Way RS ideal for time attack cars, rear-wheel drive track builds, and high-performance street cars where balance and predictability are essential.

The RS series utilizes a low initial torque coil spring pre-load system, which creates smoother engagement and quicker response compared to traditional clutch-type differentials. With optimized ramp angles and oil-immersed clutch plates for heat dissipation, the RS LSD line is designed for long-lasting, consistent performance under repeated high-load conditions.

• Locks fully under acceleration; partial locking under deceleration (1.5-Way behavior)
• Enhanced braking stability and corner entry control versus 1-Way
• Ideal for high-performance AWD and RWD setups, time attack, and responsive track builds
• RS coil spring pre-load system for smooth, consistent lockup
• Reduces lift-off oversteer while improving mid-corner balance
• Forged casing and rebuildable internals for long-term durability
• Superior thermal control through oil-immersed clutch packs
• Balanced LSD behavior that adapts to both aggressive and technical driving

Compared to the 1-Way, the 1.5-Way provides greater control on corner entry and is better suited for aggressive trail braking. It’s more forgiving than a 2-Way on the street, yet delivers the kind of on-track control that serious drivers demand.