BMW Differential Types — Open, LSD, and Electronic

What Does a Differential Do?

The differential allows the driven wheels to rotate at different speeds (essential for cornering) while transmitting power from the driveshaft to both wheels.

Open Differential

The standard differential on most BMWs. Power follows the path of least resistance — if one wheel loses traction, all power goes to that wheel (it spins while the other gets nothing).

Used on: Most non-M, non-Performance BMWs

Limited-Slip Differential (LSD)

Mechanical LSD (Clutch-Type)

Uses clutch packs to limit the speed difference between wheels. When one wheel starts spinning faster, the clutch packs engage and transfer torque to the slower wheel.

Used on: E46 M3, E36 M3, E39 M5, some E90 335i with option

Maintenance: LSD fluid must be changed every 40,000-60,000 km with friction-modified fluid (BMW 75W-140 with LSD additive).

Torsen (Torque-Sensing) LSD

Uses helical gears instead of clutch packs. Purely mechanical, no wear items.

Advantages: No maintenance, consistent behavior, long lifespan
Disadvantages: Cannot lock 100%, less aggressive than clutch-type

Electronic Differential (M Active Differential)

Used on: F80 M3, F82 M4, G80 M3, G82 M4, F10 M5, F90 M5

An electronically controlled multi-plate clutch that can vary locking from 0-100%. The DME controls locking based on:

• Wheel speed difference
• Steering angle
• Throttle position
• Yaw rate
• Selected driving mode

Advantages:

• Infinitely variable locking
• Adapts to conditions in real-time
• Can be fully open for parking/low-speed maneuvers
• Can be fully locked for maximum traction

Disadvantages:

• Complex, expensive to repair
• Fluid changes still required
• Actuator motor can fail

Differential Fluid Maintenance

Type	Fluid	Interval
Open	BMW 75W-90 GL-5	60,000 km
Clutch LSD	BMW 75W-140 + LSD additive	40,000-60,000 km
M Active	BMW 75W-140 + LSD additive	40,000-60,000 km
Torsen	BMW 75W-90 GL-5	60,000 km

Aftermarket LSD Options

For BMWs with open diffs, popular LSD retrofits include:

• Quaife ATB — Torsen-type, no maintenance
• OS Giken — Clutch-type, aggressive locking
• Wavetrac — Improved Torsen design
• Kaaz — Clutch-type, adjustable locking