Spec Clutch ST66ET Super Twin Multi-Disc Clutch Kit E-Trim

The Spec Clutch ST66ET Super Twin Multi-Disc Clutch Kit is a high-performance twin-disc clutch system engineered for street and track use in vehicles producing extreme power levels of 700–1,500 lb-ft of torque. Designed to handle serious horsepower without sacrificing daily drivability, the Super Twin delivers near-stock engagement feel while providing the grip and durability demanded by high-output builds.

The E-Trim disc configuration uses two sintered iron-type discs — SPEC's most aggressive disc compound — making this kit ideally suited for applications prioritizing maximum holding capacity and track performance.

Built entirely from billet materials, the Super Twin assembly is precision-machined from aircraft-grade aluminum and high-carbon billet steel to tolerances of .001 inch for exceptional balance and smooth actuation. Dampened, full-faced carbon graphite discs provide consistent, controlled friction engagement. Every SPEC clutch kit and flywheel is SFI approved.

Key Features:

• Rated for 700–1,500 lb-ft of torque at the flywheel
• E-Trim sintered iron disc compound — maximum holding power
• All-billet construction: aircraft-grade aluminum and high-carbon billet steel
• Precision machined to .001 inch tolerances for perfect balance and actuation
• Dampened, full-faced carbon graphite friction discs
• Near-stock drivability with no shimming or setup required — true bolt-in installation
• Maintenance-free, rebuildable design — serviceable by SPEC or the end user
• Replacement components and rebuild services always available
• Flywheel and track-spec hardware included
• SFI approved

Supported Driving Disciplines: Street, Drag, Drift, Road Racing, Time Attack, Pulling, Rallye

The SPEC Super Twin is designed, hand-built, and tested in the USA, offering a rebuild-friendly platform with long service life for builds that demand more than a single-disc clutch can provide.