A lightened flywheel allows a given engine to rev freer, that is, respond more readily to the throttle. The effect of this is unleashing more horsepower and more flexibility throughout the rev range. These are made from high-grade aluminum billet with a replaceable high-carbon steel wear surface. A steel ring gear is installed. Although most of the sales for these lightweight flywheels are to the high performance and racing market, the street-driven Jaguar will see advantages in extended engine life from a freer revving engine. Triple-plate racing clutches can be accommodated by calling with the gearbox and intended application. Note: This flywheel cannot be used with the early-type V-12 starter (Lucas number 26327). When fitting this ring gear to an early car, you must also install a later starter, either LU-26381 (rebuilt original) or 17-4002 (gear reduction).