Anticipatory and Comprehensive Differential

Anticipatory limited slip differentials generate dynamic lock prior to torque reaching the rear wheels, before there is a need for it. Anticipatory units should theoretically prevent wheel slip. However, this assumes that either both rear wheels are getting the same relative amount of traction, or that the unit has sustainable, static lock capabilities.

Without static lock, if both rear wheels are not getting comparable traction, the instant one wheel slips the differential will behave like an open, non-limited slip unit. All torque will be diverted to the slipping wheel. The more aggressive your driving, the less effective units that lack static lock will be.

The Performance Gearing limited slip is the only comprehensive and anticipatory differential that provides on-demand lock in all driving situations. It will statically and dynamically generate lock during any driving situation to prevent wheel slippage before it occurs.

Differential Lock Options

Street
30% static lock
45/45 ramp housing angles for a modest wheel slip control during cornering
30% to 70% dynamic lock options during acceleration and deceleration

Aggressive Street or Driver's Schools
40% static lock for max inside wheel spin control and avoiding understeer
30/50 ramp housing angles
40% to 100% dynamic lock during aggressive acceleration and deceleration

Dedicated Track
25%-30% static lock
40/60 ramp housing angles
30% to 100% dynamic lock during full-throttle acceleration
30% to 40% dynamic lock during aggressive deceleration

BMW Eliminated Interchangeability

During a comprehensive change in differential design, BMW eliminated the interchangeability of differential components, which was common in models between 1971 and 1994. Limited slip units have since disappeared as an option for BMW models from '95 and later.

All BMW models now have a traction control safety feature. When one rear wheel spins out of proportion of the other, the traction control system applies brake pressure to the spinning tire, retarding the car's timing and throttling down the automobile to regain control. But the driver in a vehicle equipped with traction control never experiences the power of an open differential.

Traction control is specifically designed to impede your performance. However limited slip is an important distinction for drivers who value complete control. Performance Gearing differentials allow you to regain your traction control and unleash the full potential of your BMW.

The Challenge

Since traction control is a safety feature and not a performance enhancement, the challenge was to design a limited slip unit that used the proper sized internal components - bevel gears, cross shafts, ramp housings, friction discs, etc. - and could withstand the torque and horsepower outputs of the 6 cylinder and V8/V12 engines, respectively.

Internal Components Include:

• Five 90mm ceramic coated friction discs for 6 cylinder models
• Four 106mm friction discs for twin-turbo and V8/V12 models
• Ramp housings machined for 45/45, 30/50, and 40/60 angles
• Opposing Belleville washers for maintaining static lock