ACT HD-M/Race Rigid 4 Pad Clutch Kit – 2004-2021 Subaru STI

ACT Heavy Duty Race Rigid 4-Pad Clutch Kit for the 2004-2021 Subaru WRX STI

The ACT Heavy Duty Race Rigid 4-Pad Clutch Kit for the 2004-2021 Subaru WRX STI is engineered for the EJ257’s higher torque output compared to the WRX. The ACT Heavy Duty pressure plate provides the correct clamp load for this application and the 4-pad rigid ceramic race disc is matched to the use case: track builds, 4-pad preference.

DETAILS

• Pressure plate: ACT Heavy Duty
• Clutch disc: 4-pad rigid ceramic race disc
• Use case: track builds, 4-pad preference
• Fitment: 2004-2021 Subaru WRX STI EJ257

Four ceramic pads, rigid. Lighter than 6-pad, suited for builds where the 4-pad configuration is preferred.

The STI’s EJ257 engine makes more torque than the WRX EJ25T, and the clutch selection needs to account for that. ACT’s STI-specific kits use the correct pressure plate and disc sizing for the larger disc diameter, ensuring the clamp load calculations are right for this application.

What’s in the Box

• ACT pressure plate
• ACT clutch disc
• Hardware and alignment tool
• Installation instructions

Why Choose ACT

Advanced Clutch Technology has been manufacturing performance clutch systems in the United States since 1993. Every ACT pressure plate uses a proprietary diaphragm design that increases clamp load and reduces deflection compared to OEM units, and every diaphragm goes through a four-stage heat-treating process before it leaves the factory. The result is a clutch system that holds more power than the stock unit, engages more precisely, and lasts longer under the kind of driving that wears factory clutches out quickly. ACT designs each application from scratch rather than modifying OEM tooling, which means the fitment is precise and the performance is intentional. Whether the build is a street-driven daily driver or a dedicated track car, ACT offers a kit at the correct specification for the use.

The RallySport Take

The ACT Heavy Duty 4-pad Rigid kit is for builds where daily drivability has already been traded for performance. Engagement is abrupt — there is no organic cushion and no spring damping in the hub. What you get is the fastest possible clutch engagement, ceramic friction material that does not fade under sustained track heat, and a chrome-moly hub that handles repeated aggressive launches without fatigue. This is not a commuter clutch. It is the correct choice for time attack, track days, and competition builds where every second and every shift matters. Fits Subaru applications 2004-2021.

Fitment