Spec Clutch SF664 Stage 4 Performance Clutch Kit

The Spec Clutch SF664 Stage 4 Clutch Kit is a high-performance, competition-grade clutch system engineered for heavily modified engines demanding maximum torque transfer and instantaneous engagement. As a solid hub evolution of the Stage 3, the SF664 delivers uncompromising power delivery for drivers who need every ounce of performance on the track.

At the heart of the Stage 4 design is a solid 8-rivet hub with a heat-treated assembly for exceptional strength and durability. The carbon semi-metallic friction disc is available in 3, 4, or 6-puck configurations, allowing you to tailor engagement characteristics to your specific application — choose the 3-puck for the lightest rotating assembly, the 6-puck for the smoothest engagement, or the 4-puck as a balanced compromise between the two. While the 6-puck configuration is marginally street-drivable, the rigid hub design means this kit is not recommended for street use due to its aggressive, instantaneous engagement.

Kit Includes:

• High-clamp performance pressure plate
• Carbon semi-metallic friction disc (3, 4, or 6-puck configuration)
• High-torque solid rigid hub and carrier assembly
• Throwout bearing
• Installation tool kit

Intended Use / Driving Environments:

• Drag Racing
• Drift
• Road Racing
• Rallye
• Pulling
• Circle Track

The Spec SF664 Stage 4 Clutch Kit is the choice for competition-focused builds where low rotating mass, high clamping force, and aggressive engagement are mission-critical priorities.