Toyota GT86/Subaru BRZ clutch kit + lightweight 5.7kg flywheel

Toyota GT86 / Subaru BRZ (ZN6/ZC6), a clutch kit paired with a 5.7 kg (12.5 lb) lightweight flywheel is a popular mid-tier upgrade. This specific flywheel weight is often considered the “sweet spot”—it is roughly 3kg (6.6 lbs) lighter than the OEM unit (~9.2 kg), offering significantly faster throttle response without making the car difficult to launch in traffic.

1. Popular 5.7kg Clutch & Flywheel Combinations

Several manufacturers offer kits specifically weighted at 5.7kg to balance performance and streetability:

2. Technical Impact of the 5.7kg Weight

• Throttle Response: By reducing the rotating mass by over 30%, the engine reaches its powerband faster. You will notice a significant improvement in “rev-matching” on downshifts.

• Acceleration: While it doesn’t add horsepower, it reduces the parasitic loss required to spin the heavier factory dual-mass or heavy-steel unit, effectively putting more torque to the ground in lower gears.

• Drivability: Unlike “Ultra-Lightweight” flywheels (under 4.5kg), a 5.7kg unit retains enough inertia to prevent the engine from stalling easily during hill starts or when the air conditioning compressor kicks in at idle.

3. Installation & Maintenance Notes

• Gearbox Chatter: Upgrading to a single-mass lightweight flywheel on the GT86/BRZ often introduces “transmission rattle” or “chatter” at idle, especially when the gearbox is warm. This is normal and caused by the reduction in harmonic damping.

• Torque Ratings: * Organic Kits (Stage 2): Usually rated for ~280–310 Nm (210–230 lb-ft). Best for naturally aspirated or light-bolt-on cars.

  • Ceramic Kits (Stage 3): Usually rated for 400+ Nm (300+ lb-ft). Best for forced induction (Turbo/Supercharger) applications.

• Hardware: Always use new flywheel bolts (the GT86 uses 8 bolts) and a new throw-out bearing. The 2017+ updated OEM “Kouki” throw-out bearing is recommended for better longevity.