Description Reviews The Black Flag helical gear style, limited slip differential is engineered to maximize traction on and off the track. Manufactured with premium materials to withstand high power and to be maintenance free for thousands of miles. The gears in this differential are forged using high strength SNCM616 alloy steel which can handle the high power from your vehicle.This Differential (LSD) powers both drive wheels under all conditions, instead of just one. With an ordinary open differential, standard on most cars, a lot of precious power is wasted during wheelspin under acceleration. This happens because the open differential shifts power to the wheel with less grip (along the path of least resistance). This unit, however, does just the opposite. It senses which wheel has the better grip, and biases the power to that wheel. It does this smoothly and constantly, and without ever completely removing power from the other wheel. In cornering, while accelerating out of a turn, the Quaife biases power to the outside wheel, reducing inside-wheel spin. This allows the driver to begin accelerating earlier, exiting the corner at a higher speed. This can give you a 2 to 3 second better lap times! Note: This unit will fit the R56 Cooper S. We have personally installed one and it worked!Installation Notes: It is recommended that installation of any Black Flag differential is performed by a professional mechanic. 1 Year Warranty! Black Flag provides a 1 year limited warranty to the original purchaser of any differential. The warranty covers manufacturing and material defects on product installed on intended applications. Black Flag or any of its affiliates, partners or authorized agents are not responsible for any charges or fees for labor, installation, alignment or any damage that may be associated with warranty claim. Specs: Cover Bolts: 11 Gear Material: SNCM616 Steel Gear Type: Helical Housing Material: SAE8620 Steel Material: High Strength Alloy Steel Spline Count: 34 Transmission: Getrag 285 Install Note: When installing an LSD, don't forget to buy a set of bearings.