OS Giken SB041-HA Super Lock Rear LSD for Subaru WRX STI GDB/GRB R180

Vehicle Fitment

• 2004-2007 Subaru Impreza WRX STI (GDB chassis), R180 rear differential, 6-speed manual
• 2008-2014 Subaru Impreza WRX STI (GRB chassis), R180 rear differential, 6-speed manual

Fitment Notes

• Rear differential unit only - for STI models equipped with the R180 rear differential (not R160-equipped models)
• Verify transmission and differential type before ordering, as early and late model years within this range can differ in reduction gear and diff specification
• Companion front unit (SB041-HA01) is a separate part number and sold separately

Features

• Patented pressure ring design for smooth, progressive, and quiet locking behavior
• Spline-through-side-gear design allowing fitment of up to 28 friction plates - up to 2x more than competing designs
• True 100% lock capability for consistent power delivery under hard acceleration and cornering
• Relief cut-out in the LSD case for the cone spring, reducing spring degradation and improving long-term durability
• All components chemically heat-treated for maximum durability
• Constructed from high-grade steel alloy with raw-forged gears for maximum strength
• Clutch disks precision-machined simultaneously on both sides to tight tolerances, minimizing warpage
• Suitable for both street and racing performance use

Specifications

• Differential type: R180 rear
• Lock type: Mechanical, patented Super Lock pressure ring design
• Friction plate capacity: Up to 28 plates
• Material: High-grade steel alloy, raw-forged gears
• Heat treatment: Chemically heat-treated components

Included Components

• 1x OS Giken Super Lock Rear LSD, R180, Subaru STI GDB/GRB (SB041-HA)

Product Description

The OS Giken SB041-HA Super Lock LSD is a rear limited slip differential engineered specifically for the R180-equipped Subaru WRX STI, covering both the GDB (2004-2007) and GRB (2008-2014) chassis. Built on more than four years of dedicated research and development, the Super Lock design uses a spline-through-side-gear architecture that allows for up to 28 friction plates - roughly twice the capacity of many competing LSDs - enabling true 100% lock capability without the harshness typically associated with fully locking differentials.

A patented pressure ring design delivers smooth, progressive, and notably quiet locking behavior, while a relief cut-out in the LSD case reduces cone spring degradation over time, improving long-term durability. Every component is chemically heat-treated, built from high-grade steel alloy, and finished with raw-forged gears for maximum strength, while the clutch disks are precision-machined simultaneously on both sides to minimize warpage and maintain tight tolerances.

This differential is built for STI owners who want serious, race-proven power delivery to the rear wheels - whether for club-level competition, time attack, or spirited street driving - without sacrificing durability or drivability. Since this is the rear R180 unit, owners looking to upgrade both differentials should pair it with OS Giken's separate front unit (SB041-HA01), sold individually.