Spec Clutch SA81S-3 Tuned Billet Steel Flywheel SFI 1.1 Certified

The Spec Clutch SA81S-3 is a precision-engineered billet steel flywheel designed for high-performance street and motorsport applications. Machined from high-carbon billet steel, this flywheel is manufactured to an industry-leading .001-inch tolerance — ten times tighter than the industry standard of .010 — ensuring a perfectly flat seating surface for the clutch disc and exceptional rotational balance. It carries SFI 1.1 certification, making it suitable for competitive and sanctioned racing environments.

Key Features:

• CNC-machined high-carbon billet steel construction
• Industry-leading .001-inch machining tolerance (vs. industry standard .010)
• SFI 1.1 certified for performance and safety compliance
• 135-tooth ring gear
• Internally balanced for smooth, vibration-free engine revolutions
• Engineered for diaphragm-style pressure plates
• Tuned moment of inertia (MOI) optimized for specific driving environments
• Includes crankshaft and pressure plate mounting hardware
• Sold individually

A flywheel's role in power transfer is critical: it must deliver a consistent friction surface for the clutch disc, provide the correct rotational inertia for the application, and maintain true balance at speed to eliminate power-robbing vibration. The SA81S-3 steel flywheel is tuned to provide a medium-weight inertia profile, making it well-suited for street driving, drag, pulling, and autocross use — retaining RPM between shifts for a more predictable, drivable feel compared to lighter aluminum alternatives.

Unlike generic lightweight flywheels, Spec tuned billet flywheels are engineered for specific vehicles and their unique response to changes in rotating mass. This application-specific approach optimizes clutch performance, extends clutch life, and maximizes drivetrain output across a wide range of driving conditions.