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:
| Manufacturer | Series | Disc Type | Characteristics |
| XTD Racing | Stage 2 or 3 | Organic or 6-Puck Ceramic | Often sold as a complete kit with a 5.7kg Chrome-Moly flywheel. High value. |
| Competition Clutch | Stage 2 | Steelback Brass Plus | Uses a 5.7kg flywheel in their “Lightweight” kits. Ideal for daily street use. |
| Exedy | Stage 1 Organic | Ultra-Fiber Organic | Known for OEM-like pedal feel but with a 5.7kg “Racing” flywheel for quicker revs. |
| PMC Motorsport | Race Stage 1 | Organic | Often uses a 5.7kg single-mass flywheel design for high-response builds. |
2. Technical Impact of the 5.7kg Weight
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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.
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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.
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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
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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.
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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.
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Ceramic Kits (Stage 3): Usually rated for 400+ Nm (300+ lb-ft). Best for forced induction (Turbo/Supercharger) applications.
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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.
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