ACT 6-Puck Disc Replacement SB4 – 2004-2021 Subaru STI

ACT 6-Puck Race Disc for the 2004-2021 Subaru WRX STI

The ACT 6-Puck Ceramic Race Replacement Disc for 2004-2021 Subaru WRX STI (SB4) is a standalone replacement disc compatible with ACT clutch kits and most OEM pressure plates on this application. Use case: dedicated track and competition builds.

DETAILS

• Disc type: 6-puck ceramic race
• Engagement: rigid/sprung
• Use case: dedicated track and competition builds
• Compatibility: 2004-2021 Subaru WRX STI (SB4)
• Chrome-moly hub, heat-treated

Ceramic friction material on rigid pads bonded to a rigid chrome-moly hub. Immediate engagement, fastest possible shifts, maximum heat resistance.

ACT replacement discs use the same friction materials and hub specifications as the discs included in ACT complete clutch kits. Ordering a replacement disc is the correct approach when the pressure plate is still serviceable and only the friction material is worn. Verify the specific disc reference number against your existing ACT kit to confirm compatibility.

What’s in the Box

• ACT replacement clutch disc
• 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 XACT flywheel is one of the most cost-effective modifications available for 2004-2021 Subaru STI. The OEM flywheel is significantly heavier than it needs to be — it was engineered for smooth low-RPM operation at the expense of rotational responsiveness. Reducing that rotating mass is immediately perceptible in how the engine revs through the range and how precisely you can match revs on downshifts. Installing the flywheel at clutch replacement time adds almost no incremental labor since the transmission is already out. Fits Subaru applications 2004-2021.

Fitment