An “open” differential will always send power to the wheel with the least traction, often resulting in a one-wheel burnout. A limited-slip differential (LSD) solves this problem by detecting wheel slip and redirecting torque to the wheel with more grip. In this article, we’ll explore how LSDs work and why they’re transformative for vehicle performance.

How an LSD Works

The core function of an LSD is to limit the speed difference between the two drive wheels. When one wheel starts to spin faster than the other (indicating loss of traction), the LSD engages mechanisms to transfer torque to the wheel with better grip.

This is accomplished through various mechanical systems that create resistance to wheel speed differences. The amount of resistance determines how much torque can be transferred to the wheel with traction.

Types of LSDs

There are several types of limited-slip differentials, each with distinct characteristics:

Clutch-Type (Salisbury)

This is perhaps the most common type of LSD in performance applications:

• Uses clutch packs to create friction between the differential case and the side gears
• Highly tunable with different spring pressures and clutch materials
• Requires periodic maintenance to adjust clutch pack preload

Clutch-type LSDs are often categorized by their behavior:

• 1-way: Only active under acceleration, allowing full wheel speed difference during deceleration
• 1.5-way: Active under acceleration with partial engagement during deceleration
• 2-way: Active under both acceleration and deceleration

Helical/Torsen (Torque-Sensing)

These LSDs use a system of worm gears and spur gears:

• Smooth, quiet operation with no maintenance requirements
• Works by using the geometry of the gears to create resistance to speed differences
• Can act like an open diff if one wheel has zero traction (is in the air)

Torsen differentials are often found in factory performance applications due to their reliability and smooth operation.

Viscous

These LSDs use fluid dynamics to create limited slip:

• Use a fluid that thickens with heat and shear to transfer torque
• Often found in OEM applications
• Less aggressive than mechanical LSDs and can wear out over time

Practical Benefits

LSDs provide several performance advantages:

Corner Exit

Allows the driver to apply power earlier and harder without spinning the inside tire:

• Improves acceleration out of corners
• Provides more predictable power delivery
• Reduces tire wear during spirited driving

Launch

Ensures both drive wheels are putting power down for a better launch:

• Improves straight-line acceleration
• Reduces wheel spin during hard launches
• Provides more consistent performance

Stability

Provides more predictable handling at the limit:

• Reduces oversteer during corner exit
• Improves confidence during aggressive driving
• Provides more balanced handling characteristics

Conclusion

A limited-slip differential is one of the most transformative upgrades for vehicle performance. Unlike many modifications that focus on a single aspect of performance, an LSD directly impacts how power is delivered to the road, improving acceleration, cornering, and overall vehicle balance.

Whether you’re driving on the street or track, an LSD ensures that the engine’s power is effectively utilized by both drive wheels. For enthusiasts looking to improve their vehicle’s performance, an LSD should be at the top of the modification list.