The new optional #81463 RC8B3 FT Title: New! RC8B3 FT 4-shoe steel flywheel is a direct replacement for the standard #81370 RC8B3 aluminum 4-shoe flywheel. The steel flywheel is heavier than the aluminum flywheel and increases the overall rotating mass of the clutch assembly. This offers a more stable engine idle and a smoother bottom end throttle feel.