ACT T1S-S05 Mod-Twin 225 HD Sprung Street Clutch Kit for Subaru WRX STI

T1S-S05 Mod-Twin 225 HD Sprung Street Kit is designed for high powered AWD street cars. It unites uncompromised pedal feel, durability, engagement quality with very high torque capacity by combining twice the organic friction surfaces with an ultra-durable spring center Mono-Drive hub in a completely modular design. Each diaphragm spring endures an exclusive four-stage heat treating process providing a consistent light pedal feel. Steel-backed Friction Plates with high quality organic friction materials deliver stable friction coefficient, good heat capacity and long clutch life. These Friction Plates uniformly transfer torque to the Mono-Drive sprung hub assembly which extends input shaft life and reduces driveline shock from torsional vibration. This kit includes a CNC-machined and dynamically balanced flywheel, pressure plate cover, diaphragm spring, face, puck-style ceramic friction plates, sprung Mono-Drive hub assembly, floater, patented Monoloc Collar, release bearing, alignment tool and pilot bearing (if needed). Mod-Twin clutches are fully rebuildable and most components can be ordered separately. Mod-Twin 225 HD Sprung Street Soft progressive engagement, light pedal effort, smooth shifting with OE to mild transmission gear noise; Forged Aluminum Cover, Mono-drive hub, exclusive diaphragm, premium friction materials, and hardened wear points ensure this long-life twin performs and survives under the most demanding conditions; Delivers maximum performance and high heat tolerance by combining robust design, strategic features, choice materials, and close tolerances; Street or Street/Strip; Applying tactical engineering to the Mod-Twin, ACT presents unique solutions to common tradeoffs found on twin disc clutches, resulting in an ultra-durable, customer serviceable, long-lasting clutch with very high torque capacity. All are 100% clamp load tested, balanced and SFI certified

• "Excellence in Performance", backed by the best one-year warranty in the industry!

The ACT T1S-S05 Mod-Twin 225 HD Sprung Street Kit is engineered for high-powered AWD street cars, including the 2015-2018 Subaru WRX STI. It combines high torque capacity, smooth engagement, light pedal effort, and long-term durability in a fully modular twin-disc clutch system. The kit uses two organic friction surfaces with a sprung Mono-Drive hub to improve torque transfer, reduce driveline shock, and help protect the transmission input shaft.

Each diaphragm spring undergoes ACT’s exclusive four-stage heat-treating process for consistent clamp performance and a progressive pedal feel. Steel-backed friction plates with premium organic friction material provide stable friction characteristics, strong heat tolerance, and extended service life. The forged aluminum cover, hardened wear points, dynamically balanced flywheel, and close-tolerance construction support dependable performance in demanding street and street/strip applications. Engagement remains smooth, with OE-like to mild transmission gear noise during normal operation.

The ACT Mod-Twin design is fully rebuildable, allowing major components to be serviced or replaced separately when needed. Every clutch is clamp-load tested, dynamically balanced, and SFI certified. The kit includes the clutch hardware required for installation, along with ACT’s patented Monoloc Collar and a one-year manufacturer warranty.

Product Specifications & Technical Data

• Application: High-powered AWD street and street/strip vehicles
• Clutch Design: Mod-Twin 225 HD sprung twin-disc system
• Hub Design: Sprung Mono-Drive hub assembly
• Friction Material: Premium organic friction plates with steel backing
• Torque Capacity: Up to 700 lb-ft
• Cover Construction: Forged aluminum cover with hardened wear points
• Performance Testing: 100% clamp-load tested and dynamically balanced
• Certification: SFI certified; fully rebuildable modular design

What's Included

• CNC-machined and dynamically balanced flywheel
• Pressure plate cover and diaphragm spring
• Two puck-style ceramic friction plates
• Sprung Mono-Drive hub assembly
• Floater
• Patented Monoloc Collar
• Release bearing
• Alignment tool
• Pilot bearing, when required

Fitment includes select 2015-2018 Subaru WRX STI applications. Verify the vehicle year, drivetrain configuration, transmission, and installation requirements before ordering.

Features:

• High Torque Capacity: Supports up to 700 lb-ft while maintaining reliable torque transfer for powerful AWD street cars.
• Sprung Mono-Drive Hub: Helps absorb torsional vibration, reduce driveline shock, and extend transmission input shaft life.
• Smooth Street Engagement: Delivers progressive engagement, light pedal effort, and smooth shifting with OE-like to mild gear noise.
• Fully Rebuildable Design: Modular construction allows service or replacement of individual components for extended clutch system life.

Fitments:
2004 Subaru Impreza WRX STI
2005 Subaru Impreza WRX STI
2006 Subaru Impreza WRX STI
2007 Subaru Impreza WRX STI
2007 Subaru Impreza WRX STI Limited
2008 Subaru Impreza WRX STI
2009 Subaru Impreza WRX STI
2010 Subaru Impreza WRX STI
2010 Subaru Impreza WRX STI Special Edition
2011 Subaru Impreza WRX STI
2011 Subaru Impreza WRX STI Limited
2012 Subaru Impreza WRX STI
2012 Subaru Impreza WRX STI Limited
2013 Subaru Impreza WRX STI
2013 Subaru Impreza WRX STI Limited
2014 Subaru Impreza WRX STI
2014 Subaru Impreza WRX STI Limited
2015 Subaru WRX STI Base
2015 Subaru WRX STI Launch Edition
2015 Subaru WRX STI Limited
2016 Subaru WRX STI Base
2016 Subaru WRX STI Limited
2016 Subaru WRX STI Series.HyperBlue
2017 Subaru WRX STI Base
2017 Subaru WRX STI Limited
2018 Subaru WRX STI Base
2018 Subaru WRX STI Limited
2018 Subaru WRX STI Type RA
2019 Subaru WRX STI Base
2019 Subaru WRX STI Limited
2019 Subaru WRX STI S209
2020 Subaru WRX STI Base
2020 Subaru WRX STI Limited
2021 Subaru WRX STI Base
2021 Subaru WRX STI Limited

Air Freight Prohibited: false
Not Carb Approved: false
Ltl Freight Required: false
Prop 65: Y
Part Type: automotive
Epa: N/A
Carb Acknowledgement Required: false
Regular Stock: t
Units Per Sku: 1