Controlling Power Distribution
The differential is one of the most critical yet often overlooked components in your drivetrain. Positioned between the transmission and the drive wheels, the differential splits engine torque while allowing each wheel to rotate at different speeds during turns. This fundamental function enables smooth cornering, but the way a differential manages torque distribution dramatically affects traction, handling characteristics, and your ability to put power to the ground effectively. Upgrading your differential transforms how your vehicle responds under acceleration, through corners, and in varying traction conditions.
Types of Limited Slip Differentials
Mechanical limited slip differentials use various methods to limit wheel speed differences and distribute torque. Clutch-type LSDs use friction plates that engage under torque load, providing progressive locking behavior that transfers power to the gripping wheel. Gear-type differentials such as Torsen and Quaife units use helical gearing to automatically bias torque toward the slower wheel without friction surfaces that wear over time. These designs offer smooth, maintenance-free operation with immediate torque transfer response. Locking differentials, common in off-road and drag racing applications, mechanically connect both wheels to spin at identical speeds regardless of traction differences—maximizing straight-line traction but limiting their suitability for street use due to binding during turns.
One-Way, 1.5-Way, and Two-Way LSDs
Clutch-type limited slip differentials are further categorized by their locking behavior during acceleration and deceleration. A one-way LSD provides locking action only under acceleration, remaining open during coast and braking. A two-way LSD locks equally under both acceleration and deceleration, providing predictable behavior but potentially inducing oversteer on corner entry during deceleration. A 1.5-way LSD offers a compromise, providing full locking under acceleration and reduced but present locking during deceleration. The appropriate choice depends on driving style and application—one-way for street and grip-focused driving, two-way for drifting where decel locking helps initiate slides, and 1.5-way for balanced performance driving and time attack applications.
Ring and Pinion Gear Sets
The ring and pinion gears within your differential determine final drive ratio—the last multiplication of torque before power reaches the wheels. Factory gear ratios balance acceleration with fuel economy and cruising rpm. Performance gear sets with numerically higher ratios (such as moving from 3.73 to 4.10) increase torque multiplication, improving acceleration at the cost of higher highway rpm and slightly reduced top speed. Lower numerical ratios have the opposite effect. Gear changes are particularly beneficial when combined with tire size changes that affect effective gearing, or when engine modifications have shifted the powerband in ways that make stock gearing less optimal.
Differential Bushings and Supporting Components
The differential itself mounts to the chassis through bushings that isolate vibration while maintaining proper positioning. Factory rubber bushings deteriorate over time and allow excessive differential movement under load. Upgraded differential bushings using polyurethane or solid construction reduce this movement, improving power delivery consistency and drivetrain feel. Differential output seals, bearings, and related hardware should be inspected and replaced as needed during differential service to ensure reliable operation and prevent fluid leaks.
Vehicle Applications
Our differential selection covers Subaru WRX, STI, BRZ, Forester XT, and Legacy GT; Honda Civic, Civic Type R, S2000, and Accord; Toyota GR86, Supra, 86, and MR2; Nissan 370Z, 350Z, GT-R, and 240SX; Mazda MX-5 Miata, RX-7, and RX-8; Mitsubishi Lancer Evolution; BMW M series; and additional performance platforms requiring improved traction and power distribution.