Exedy Hyper Twin Cerametallic Clutch – Sprung Disc | Pull-Type | 2004–2014 Subaru WRX STI | EJ257 | GD / GR | FM022SD

Exedy FM022SD Hyper Twin cerametallic clutch kit with sprung disc for the 2004–2014 Subaru Impreza WRX STI (EJ257, GD and GR chassis). Pull-type actuation. Approximately 500 ft-lbs torque capacity at the flywheel — engineered for high-boost EJ257 builds where the OEM single-plate clutch is the limiting factor. The sprung disc (SD) variant retains spring-damped engagement for street/track dual-purpose use. 35.2 lbs. Ships fast across Canada and the US.

Exedy Hyper Twin — Twin Plate Architecture

The Hyper Twin replaces the OEM single friction disc with a twin-plate assembly — two friction discs clamped by a redesigned pressure plate:

• Torque capacity: The OEM STI clutch is typically rated at 270–300 ft-lbs at the flywheel in OEM form. Exedy’s Hyper Twin achieves approximately 500 ft-lbs at the flywheel — a near-doubling of torque capacity achieved through additional friction surface area rather than excessive clamp load increase. High clamp load alone (as used in some single-plate performance clutches) produces pedal effort increases that make the clutch fatiguing in daily use. The twin plate approach maintains a manageable pedal weight while dramatically raising the torque limit.
• Friction surface area: Two discs mean two pad-to-flywheel and two pad-to-pressure plate friction interfaces — quadrupling the friction interface count vs a single-plate clutch. At equivalent clamp load, this doubles the torque capacity; Exedy optimises clamp load for a balance of capacity and pedal feel.
• Engagement: Twin plate clutches inherently have a shorter engagement stroke than single plate — the pedal travel from slip to lock-up is compressed. This requires adaptation from drivers accustomed to OEM single-plate feel, but is characteristic of all twin plate clutches regardless of brand.

Cerametallic Friction Material

The FM022SD uses cerametallic (ceramic metallic) compound friction pads on both discs:

• Friction coefficient: Higher than OEM organic compounds — more grip per unit of clamp load, contributing to the Hyper Twin’s torque capacity without requiring excessive spring pressure.
• Temperature resistance: Cerametallic compounds maintain friction coefficient at higher sustained temperatures than organic compounds — relevant for launches, sustained high-power track use, and situations where clutch slippage generates heat.
• Engagement character: Cerametallic is more aggressive than organic — engagement is more binary (less progressive slip zone) particularly when cold. Drivers need to adapt technique, especially for low-speed manoeuvring. The clutch becomes more manageable once at operating temperature.
• Flywheel wear: Cerametallic compounds are harder on flywheel friction surfaces than organic compounds. Flywheel resurfacing or replacement should be planned as part of every clutch service interval. An OEM or aftermarket flywheel at or above minimum thickness is required.
• Street use: Manageable for combined street/track use by an experienced driver familiar with performance clutch behaviour. Not recommended as a primary commuter vehicle clutch for stop-and-go city driving — the engagement characteristics create driver fatigue in heavy traffic.

Sprung Disc (SD) — Why It Matters

The FM022SD’s “SD” designation indicates sprung disc — the friction discs use a spring damper hub rather than a solid rigid hub. This is a critical specification for street/track dual-purpose use:

• Spring damper hub: Torsional springs in the disc hub absorb driveline shock and vibration during engagement and low-speed manoeuvring. Without spring damping, driveline shock from abrupt engagement transmits directly into the transmission input shaft, gearbox, and driveshaft — accelerating wear on these components and creating harsh engagement character.
• vs solid disc: Exedy also offers solid disc (no spring damper) twin plate variants. Solid discs provide slightly higher torque capacity and are appropriate for dedicated competition builds — but are not recommended for street use due to harsh NVH (noise, vibration, harshness) characteristics and accelerated ancillary drivetrain wear. The FM022SD with sprung discs is the correct choice for a high-power STI that will be driven on the road.

Pull-Type System — STI vs WRX

The 2004–2014 Subaru WRX STI uses a pull-type clutch release mechanism — the release bearing pulls the pressure plate’s release fingers inward to disengage the clutch, rather than pushing them outward as in a conventional push-type system. This is an OEM STI-specific design:

• STI (GD 2004–2007 and GR 2008–2014): Pull-type release system. FM022SD is the correct application.
• WRX (GD 2004–2007 and GR 2008–2011): Push-type release system. FM022SD will not function correctly in a WRX application. A different Exedy Hyper Twin part number is required for WRX.

Confirm your vehicle is the STI (not WRX) variant before ordering. VIN verification or inspection of the existing clutch release bearing type will confirm pull vs push-type.

GD and GR STI Coverage

• GD Impreza WRX STI (2004–2007): Sedan and wagon body styles. EJ257 2.5L twin-scroll turbocharged flat-four. Pull-type clutch. Both covered by FM022SD.
• GR Impreza WRX STI (2008–2014): Sedan and hatchback body styles. EJ257 — same engine family, pull-type clutch system continued. All covered by FM022SD.

Installation and Flywheel Requirements

Twin plate clutch installation is more involved than a standard single-plate replacement:

• Flywheel: The FM022SD requires a compatible flywheel machined to the correct twin-plate friction surface specification. The OEM STI flywheel can be used if resurfaced to minimum thickness and checked for proper mounting dimensions. Aftermarket lightweight flywheels must be confirmed compatible with Exedy’s Hyper Twin twin-plate disc interface before purchase. Flywheel is not included.
• Release bearing: A pull-type release bearing compatible with the Hyper Twin pressure plate is required. Confirm whether the kit includes a release bearing or if one must be sourced separately.
• Professional installation: Twin plate alignment requires a two-disc alignment tool and precise torque procedure. Improper installation can cause premature disc wear, vibration, or release bearing damage. Professional installation by a drivetrain specialist familiar with pull-type twin plate setups is strongly recommended.
• Break-in: Cerametallic clutches require a break-in period of approximately 500–1,000 km of progressive engagement — avoid full-power launches or sustained slipping until the compound and flywheel surface have bedded in.

STI pull-type only — not for WRX. GD 2004–2007 and GR 2008–2014 STI. Sprung disc — street/track dual use. Cerametallic — more aggressive than OEM, cold engagement requires adaptation. ~500 ft-lbs at flywheel. Flywheel not included — confirm compatibility. Professional installation required.

Specifications

• Brand: Exedy
• Part Number: FM022SD
• Type: Hyper Twin — twin plate cerametallic clutch
• Disc type: Sprung disc (spring damper hub)
• Release type: Pull-type
• Torque capacity: Approximately 500 ft-lbs at flywheel
• Friction material: Cerametallic
• Application: 2004–2014 Subaru Impreza WRX STI — EJ257 — GD (2004–2007) / GR (2008–2014) — STI only
• Weight: 35.2 lbs (complete kit)