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Cusco RS Type Metal Plate LSD

Cusco RS Type LSD's are a metal plate type limited slip. Initial torque is generated by coil springs rather than the typical cone springs which creates more progressive locking characteristics and improved sensitivity to throttle inputs. RS-Type LSD pressure rings have two ramp angle options allowing for tuning of the LSD to the conditions. High tensile forged chromoly side & pinion gears, case, and other components ensures reliability under extreme horsepower applications. "Oil Through System" case design maximizes LSD cooling and reliability. RS type LSD's are excellent for a wide range of applications owing to their wide range of adjustability and smoother progressive operating characteristics.

Popular applications usually ship within 2 to 3 days.

Manufacturer: Cusco


  • Subaru STI
  • Subaru Legacy Spec B (TY856)

Can you explain the difference between a 1-way, 1.5-way, and 2-way limited slip? This describes the drive and coast sides of the pressure ring ramps. The pressure ring compresses the LSD clutches when torque is applied. The percentage of applied torque that is directed toward the clutches is dependent on the ramp angle. A 1-way LSD has a ramp angle only on the drive side (acceleration) of the pressure ring. On the coast side (deceleration) the ramp angle is 0 degrees so no pressure is applied to the clutches. A 2-way LSD has equal ramp angles in the drive and coast directions and therefore will have significant diff locking pressure when decelerating. A 1.5-way LSD has unequal ramp angles whereby the coast side angle is steeper and provides reduced diff locking pressure when decelerating.

When should a 1-way, 1.5-way, and 2-way LSD be used? Driver preference is a big part of it. More diff locking pressure on deceleration helps with braking stability but negatively affects the handling balance at corner entry. When a 2-way LSD is installed at the front of the car there will be an undesirable understeer characteristic. For this reason a 2-way LSD is rarely used at the front of a car. Typically a 1.5-way LSD is used on loose surfaces and a 1-way LSD used on tarmac surfaces. In the rear diff a 2-way LSD can be used on a wide range of surfaces without severe handling issues. However, a 1.5-way LSD is tyipcally used on tarmac and a 1-way may be preferred in low speed courses with very tight tarmac corners (such as autocross and some types of gymkhana competition). The amount of initial (breakaway) torque may also influence the type of LSD that the driver prefers in certain locations.

What is the difference between Cusco RS Type and MZ Type limited slips? The difference is primarily in the type of spring used to preload the clutch plates and provide the initial torque. The RS Type LSD uses a set of coil springs between the pressure rings which provides a low initial torque value but assists with pressure ring activiation making the LSD very sensitive to throttle application allowing for increased mid-corner finesse and control. The MZ Type LSD uses the more traditional belleville (cone) spring which has a high initial torque and locking efficiency. On low traction surfaces the MZ Type LSD can provide increased forward traction and stability over the Type RS. Driver preference is important in deciding which LSD is the correct choice. Additionally, the RS Type LSD's lower initial torque will noticeably reduce the clutch plate wear and extend the rebuild schedule when compared to the MZ Type. Most street driven applications will be better suited to the RS Type operating characteristics.

What type of oil should be used with these LSD's? For optimum performance and reduced wear and noise these LSD's require LSD-specific oils. Cusco offers gear oils that are specifically blended to optimize the performance of their limited slip diffs. However, in applications where the limited slip is packaged within and shares the oil supply of a synchronized gearbox, such as a Subaru, there will be some tradeoff in synchro performance for limited slip performance. In cases where synchro life and performance is not adequate with an LSD type oil we suggest using Motul Gear 300.

Is there a break-in process with these LSD's? All clutch type limited slip diffs will function with better performance and less noise if they are properly broken in. The break-in process generally involves running in a constant low speed figure-8 pattern for approximately 30 minutes followed by changing the oil. This process smooths and burnishes the clutch plates and ensures even contact between the friction surfaces of the plates.