Spec Clutch SD43MODA SFI-Certified Aluminum Flywheel CNC Billet Rebuildable

The Spec Clutch SD43MODA is a precision-crafted aircraft-quality billet aluminum flywheel engineered for high-performance street and racing applications. Manufactured to an industry-leading .001-inch machine tolerance—ten times tighter than the industry standard of .010 inches—this flywheel delivers exceptional rotational balance, a perfectly flat clutch disc seating surface, and enhanced engine longevity. All SPEC flywheels carry SFI certification, making them suitable for competitive and sanctioned racing environments.

Key Features:

• Aircraft-quality billet aluminum construction for a lightweight, high-strength build
• CNC machined to .001-inch tolerance for perfect balance and zero damaging dimensional runout
• Replaceable steel friction plate made from a friction-enhancing alloy specially formulated for optimum clutch bedding and holding power
• Rebuildable design — replacement friction plates and rebuild services are available
• SFI certified for use in competitive and sanctioned racing events
• Engineered for optimized Moment of Inertia (MOI) to maximize power transfer and acceleration for your specific application
• Suitable for a wide range of motorsport disciplines including street performance, drag racing, drift, road racing, rallye, and autocross

A flywheel's contribution to drivetrain performance is three-fold: it provides a consistent friction surface for clutch disc engagement, contributes the correct rotational inertia to balance power delivery and acceleration, and must maintain true balance at high RPM to prevent vibration and power loss. SPEC engineers each flywheel with application-specific dimensions and weights, optimizing MOI based on factors such as engine output, gear ratios, tire type, and vehicle weight. The aluminum construction offers a lightweight option ideal for high-revving and performance-focused builds where reduced rotating mass is a priority.