Spec Clutch SB28A Aluminum Flywheel SFI Certified Billet

The Spec Clutch SB28A is a precision-engineered billet aluminum flywheel designed for performance street and competition use. CNC machined to an industry-leading .001-inch tolerance — ten times tighter than the industry standard of .010 — this flywheel delivers exceptional rotational balance and a perfectly flat friction surface for optimal clutch disc bedding. All SPEC aluminum flywheels carry SFI certification, making them suitable for sanctioned competition environments.

The flywheel body is constructed from aircraft-quality billet aluminum (6061-T6 or 2024-T3) for maximum strength at the lowest possible weight. A replaceable 1/4-inch thick 1050 high-carbon alloy steel friction plate is secured to the body using aerospace-grade fasteners or stainless steel rivets, providing outstanding durability and compatibility with all clutch disc materials. The ring gear is heat-treated and pressed on with Grade 10 fasteners for long-term reliability.

Key Features:

• CNC machined to .001-inch tolerance for perfect balance and true runout-free operation
• Aircraft-quality billet aluminum construction — 6061-T6 or 2024-T3
• Replaceable 1050 high-carbon alloy steel friction plate (1/4-inch thick)
• Aerospace fasteners or stainless steel rivets secure the friction plate
• SFI certified for competition use
• Rebuildable design extends service life
• Heat-treated, pressed-on ring gear with Grade 10 fasteners
• Optimized MOI (Moment of Inertia) for reduced rotating mass and faster engine response

SPEC engineers each flywheel with application-specific dimensions and weight targets to optimize Moment of Inertia (MOI) for the intended use — whether drag racing, road racing, autocross, or performance street driving. By reducing rotating mass compared to a stock flywheel, the SB28A helps the engine rev more freely, improving throttle response and overall performance. The rebuildable design with replaceable friction plate ensures long-term value for serious enthusiasts and competitors.