Ring and pinion gears are the automotive hardware that rotates the wheels of a car backwards and forwards; they work in conjunction with the drive shaft to create torque for the drive wheels, The pinion and drive shaft are attached and therefore must spin together to generate enough torque that in turn creates the power that moves the wheels forward. These Speedmaster™ ring and pinion sets are engineered, manufactured and tested for maximum performance. These ring and pinion sets are CNC-cut from 8620 steel for outstanding durability, factory-lapped for a precise fit, and Rockwell-tested for hardness. Available in many different ratios to fit a variety of differentials.