OS Giken Super Lock LSD – Toyota GT86 / Scion FR-S (ZN6/ZC6) | Clutch-Pack Limited Slip Differential

The OS Giken Super Lock LSD for the Toyota GT86 and Scion FR-S (ZN6/ZC6 chassis) is one of the most highly regarded limited slip differential upgrades available for this platform — a purpose-built, motorsport-proven clutch-pack LSD engineered by OS Giken, one of Japan's most respected high-performance differential manufacturers, to replace the factory open or Torsen differential and deliver the locked, predictable power delivery that the GT86/FR-S platform's performance potential demands. The ZN6/ZC6 chassis is widely regarded as one of the finest handling platforms of its generation — a near-perfect front-to-rear weight balance, low centre of gravity, and a naturally balanced chassis that rewards driver skill. The factory differential, however, is a significant limiting factor in extracting the platform's full performance potential — particularly in cornering, track use, and drift applications where the ability to put power down through both rear wheels simultaneously is critical. The OS Giken Super Lock LSD eliminates this limitation — delivering the locked, consistent power delivery that allows the GT86/FR-S chassis to perform to its potential.

Key Features:

• OS Giken Super Lock clutch-pack LSD — OS Giken's proven high-performance clutch-pack limited slip differential design — engineered for motorsport and serious performance applications where consistent, locked power delivery is required
• Direct replacement for factory differential — engineered as a direct replacement for the factory GT86/FR-S open or Torsen differential — installs in the factory differential housing without modification
• ZN6/ZC6 specific — engineered for the Toyota GT86 and Scion FR-S ZN6/ZC6 chassis — correct gear ratios, clutch pack specification, and dimensions for the platform's differential housing
• Motorsport-proven design — OS Giken Super Lock LSD units are used in professional motorsport and serious competition applications across Japan and internationally — a proven design validated in the most demanding conditions
• Adjustable engagement characteristics — OS Giken Super Lock LSD clutch pack preload and ramp angles can be configured for the driver's specific application — from street performance to full competition use
• OS Giken quality — manufactured by OS Giken, one of Japan's most respected high-performance differential brands with decades of motorsport development experience

Why the GT86 / FR-S Needs an LSD Upgrade:

• Factory Differential Limitation: The Toyota GT86 and Scion FR-S were equipped from the factory with either an open differential or a Torsen-type limited slip differential depending on the market and trim. The open differential provides zero torque biasing — power follows the path of least resistance, meaning the inside rear wheel spins freely under cornering load while the outside wheel receives minimal torque. The Torsen provides some torque biasing but is limited in its engagement under the conditions where an LSD is most needed — high-slip, high-load cornering and track use. Neither provides the consistent, locked power delivery that the GT86/FR-S chassis is capable of exploiting.
• Clutch-Pack LSD Advantage: A clutch-pack LSD like the OS Giken Super Lock uses a set of friction clutch plates to mechanically lock the differential under load — forcing both rear wheels to rotate at the same speed when the clutch pack engages. This provides consistent, predictable power delivery to both rear wheels under cornering load, acceleration out of corners, and in drift applications — allowing the driver to use the full torque of the FA20 engine through both rear wheels rather than losing it to the spinning inside wheel.
• Track Performance: On track, the OS Giken Super Lock LSD transforms the GT86/FR-S's corner exit performance — the ability to apply throttle earlier and more aggressively out of corners without the inside wheel spinning up is a significant lap time improvement. The consistent power delivery also improves the car's balance and predictability at the limit — allowing the driver to exploit the chassis's natural balance more fully.
• Drift Application: The GT86/FR-S is one of the most popular drift platforms globally — and the OS Giken Super Lock LSD is one of the most respected LSD choices for drift use on this platform. The clutch-pack design provides the consistent, locked rear axle behaviour that drift technique requires — predictable rotation initiation, consistent angle maintenance, and reliable power delivery through the rear wheels throughout the drift.

Specifications:

• Brand: OS Giken
• Part Number: OSGTY421-HA
• Barcode: TY421-HA
• Type: Super Lock clutch-pack LSD
• Application: Toyota GT86 (ZN6) / Scion FR-S (ZC6)
• Weight: 21.7 lbs (shipping weight)
• Required Fluid: OS Giken 80W-250 gear oil (sold separately)

Fitment Information:

• Toyota GT86 — ZN6 chassis (2012–2021)
• Scion FR-S — ZC6 chassis (2013–2016)
• Note: Also verify compatibility with the Subaru BRZ (ZC6) which shares the same platform — confirm OSGTY421-HA fitment for your specific variant. Professional installation by an experienced drivetrain specialist strongly recommended. OS Giken 80W-250 gear oil is required — do not use standard 75W-90 or 75W-140 gear oil in this LSD.

Required Fluid:

OS Giken 80W-250 gear oil is required for this LSD. The OS Giken Super Lock LSD's clutch pack design requires the specific viscosity and friction characteristics of OS Giken's 80W-250 gear oil for correct engagement, release behaviour, and clutch pack longevity. Using standard 75W-90 or 75W-140 gear oil will result in incorrect LSD behaviour and accelerated clutch pack wear. OS Giken 80W-250 gear oil is available separately at Straight Six Imports.

What's Included:

• OS Giken Super Lock LSD unit — Toyota GT86 / Scion FR-S ZN6/ZC6 (OSGTY421-HA)
• Refer to OS Giken's product documentation for complete kit contents
• OS Giken 80W-250 gear oil is not included — must be purchased separately

Installation Notes:

• Professional installation by an experienced drivetrain specialist strongly recommended — differential replacement requires correct setup procedures including backlash measurement, bearing preload, and correct torque specifications
• OS Giken 80W-250 gear oil is required — do not fill with standard 75W-90 or 75W-140 gear oil. Source OS Giken 80W-250 before installation.
• Inspect the differential housing, ring gear, and pinion for wear before installation — installing a new LSD into a worn differential housing or with a worn ring and pinion will compromise the LSD's performance and longevity
• Set backlash and bearing preload to OS Giken's specified values during installation — incorrect setup will affect LSD engagement characteristics and long-term reliability
• Follow OS Giken's recommended break-in procedure after installation — new clutch pack LSD units require a break-in period to correctly seat the clutch plates before full-load use
• Follow OS Giken's recommended fluid change interval — competition use requires more frequent changes due to elevated temperatures and clutch pack wear debris accumulation

Why OS Giken?

OS Giken is one of Japan's most respected high-performance differential and engine component brands — known for their Super Lock LSD differentials, close-ratio gearboxes, and engine components used in professional motorsport and serious performance applications across Japan and internationally. OS Giken's Super Lock LSD is among the most highly regarded limited slip differentials available for Japanese performance platforms — used by professional racing teams, drift competitors, and serious performance drivers who demand the highest level of differential performance and reliability. For GT86 and FR-S owners who want the best available LSD upgrade for their platform from a brand with genuine motorsport credentials, the OS Giken Super Lock is the correct choice.

Perfect For:

• Toyota GT86 and Scion FR-S owners who want the most capable, motorsport-proven LSD upgrade available for the ZN6/ZC6 platform — eliminating the factory differential's limitations for track, street performance, and drift applications
• GT86/FR-S track day and time attack builds where consistent, locked power delivery out of corners is a significant lap time improvement over the factory open or Torsen differential
• GT86/FR-S drift builds where the OS Giken Super Lock's consistent clutch-pack engagement provides the predictable, locked rear axle behaviour that drift technique requires
• Owners who want OS Giken's motorsport-proven Super Lock design and the peace of mind of a differential built by one of Japan's most respected performance differential manufacturers

Critical Note: OS Giken 80W-250 gear oil is required — do not use standard gear oil. Available separately at Straight Six Imports. Professional installation required — correct backlash, bearing preload, and break-in procedure are essential. Verify ZN6/ZC6 fitment for your specific GT86/FR-S variant before ordering.