OS Giken SuperLock LSD, BMW E31

OS Giken SuperLock LSD for BMW E31 840i / 840Ci / 850Ci / 850CSi – Precision Limited Slip Differential

Give your BMW E31 the performance it deserves with the OS Giken SuperLock LSD. Engineered for BMW 840i, 840Ci, 850Ci, and 850CSi models, this advanced limited slip differential enhances traction, cornering control, and overall drivability—on both street and track.

Unlike typical LSD units, OS Giken’s patented pressure ring and spline-through-side-gear design allows for up to twice the number of friction plates compared to conventional units. The result? Smooth, quiet, and consistent lockup with low preload and full 100% lock capability under aggressive driving conditions.

Key Features:

• Patented pressure ring design for progressive locking behavior

• Spline-through-side-gear design increases friction plate capacity

• Low preload + full lock potential = excellent balance of comfort and performance

• Components chemically heat-treated for maximum durability

• Constructed from high-grade forged steel for extreme strength

• Billet-machined LSD case for perfect fit and structural integrity

• Dual-surface precision-machined clutch discs minimize distortion and wear

This LSD upgrade is ideal for replacing your E31’s open differential or worn factory LSD. It delivers improved rear-end stability, especially under throttle in high-power applications, while retaining quiet operation and smooth engagement during daily driving.

Specifications:

• Ramp Angles: 25 / 35
• Lock Timing: 336
• Friction Plates: 20
• Preload: 10S

Fitment:

• BMW E31 840i Manual with Final Drive 1214053
• BMW E31 840Ci Manual with Final Drive 1214053
• BMW E31 840Ci Automatic with Final Drive 1428507
• BMW E31 850Ci Manual with Final Drive 2227445
• BMW E31 850CSi Manual with Final Drive 2227445

Installation Notes:
Refer to the OEM BMW service manual. Professional installation is strongly recommended.