BMW OS Giken SuperLock LSD

OS Giken SuperLock LSD for BMW

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The OS Giken SuperLock Limited Slip Differential is widely regarded as one of the most advanced clutch-type LSDs available for BMW platforms. Using OS Giken’s patented pressure ring design, the Super Lock delivers smooth, progressive, and fully controllable locking behavior while fitting directly into your OEM BMW differential housing.

Unlike traditional clutch LSDs that rely on high preload or abrupt lock engagement, the OS Giken Super Lock is engineered to achieve predictable, quiet operation with low preload, while still maintaining the ability to deliver true 100% lock under load. This makes it exceptionally well-suited for road course racing, time attack, drifting, and high-power street/track builds.

The Super Lock uses a spline-through side gear design, allowing OS Giken to package significantly more friction plates than most competitors—often up to twice as many clutch plates. The increased surface area improves torque capacity, heat resistance, and long-term durability, even in demanding motorsports environments.

Construction & Design Features

Patented pressure ring design for smooth, progressive lock engagement
Salisbury-style clutch LSD for maximum motorsports performance
Spline-through side gear design for increased clutch plate capacity
Raw-forged gears for superior strength and fatigue resistance
High-grade steel alloy construction throughout
Chemically heat-treated internal components for maximum durability
Precision-machined clutch discs, machined on both sides simultaneously to minimize warpage
LSD case machined from a single billet piece for strength and uniformity

Performance & Street Manners

The standard OS Giken BMW specification is designed to run low initial preload while still delivering strong, progressive lock as torque increases. Engagement is smooth and predictable, with none of the harshness often associated with aggressive clutch LSDs.

When replacing an open differential, the improvement in traction, stability, and driver confidence is immediate—without sacrificing daily drivability. Even in tight parking maneuvers, these differentials operate quietly and smoothly, with no tire chirping or binding commonly found in lower-plate or high-preload LSD designs.

Tunability & Custom Setup

One of the biggest advantages of the OS Giken Super Lock is its exceptional tunability. For higher-power applications or specific driving styles, we offer in-house setup and tuning services to tailor the differential to your vehicle and use case.

Available tuning options include:

Initial torque adjustment via thicker or thinner cone springs
Lock progression timing adjustment using stiffer or softer pressure ring springs
Ramp angle customization by swapping pressure rings and iron cross components
TCD specification clutch discs for improved oil cooling and even smoother engagement

Higher power levels often demand different differential behavior. We can speed up or slow down lock engagement to help the car put power down more effectively and maintain traction at the limit. Check out our tuning service [HERE]

BMW Application Versions & Specifications

BMW E36/E46/E9X M3 & E39 M5 - Large Case