ACT Clutch Release Bearing / Throwout Bearing - 2004-2021 STI

Smooth Engagement, Shift After Shift
The ACT Clutch Release Bearing (RB601), commonly known as a throwout bearing (TOB), is a premium, high-quality component engineered to ensure flawlessly smooth clutch disengagement. Often overlooked during a transmission overhaul, the release bearing undergoes extreme stress and heat cycles every time you press down the clutch pedal. ACT manufactures this direct-replacement bearing to meet or exceed original equipment (OE) standards, providing the long-term reliability and precise alignment needed for both heavily modified track cars and high-performance daily drivers.

Heavy-Duty Multi-Platform Precision
Designed specifically for pull-type transmission configurations, the RB601 features robust all-steel construction, durable internal ball bearings, and self-aligning capabilities to prevent binding and uneven wear on your pressure plate's diaphragm fingers. Whether you are performing a regular clutch service or pairing it with a high-clamping force kit like the ACT SB10-HDSS, dropping a fresh RB601 into your transmission housing eliminates annoying bearing squeals, rough pedal travel, and premature drivetrain wear.

• Meets or Exceeds OE Specifications: Precision-machined to ensure original factory tolerances or better.
• Self-Aligning Geometry: Helps eliminate uneven pressure distribution and friction across the clutch assembly.
• High-Performance Construction: Engineered specifically to tolerate the aggressive forces produced by sports clutches.
• Direct-Fit Installation: Drops effortlessly onto your existing fork arrangement with no extra adaptation needed.

Technical Specifications:

• Part Number: RB601
• Component Type: Clutch Release (Throwout) Bearing
• Material: Grade-A Steel
• Bearing Configuration: Round / Ball Bearing Style
• Internal Diameter: 33.0 mm (1.30 in.)
• Outer Diameter: 73.9 mm (2.91 in.)
• Self-Aligning: Yes
• Product Weight: 0.8 lbs
• Warranty: 12-Month Limited Manufacturer Warranty

Fitment:

Subaru

• Subaru WRX STI: 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021 (2.5L Turbo 6-Speed Manual)
  • Compatible with all North American trims (US/Canada): Base, Limited, Special Edition, Launch Edition, Series.HyperBlue, Type RA, S209, Sport, Sport-tech, Tsurugi Edition, and Kanrai Edition.
• Subaru Impreza WRX: 2002, 2003, 2004, 2005 (2.0L Turbo 5-Speed Manual)
• Subaru Legacy GT spec.B: 2007, 2008, 2009 (2.5L Turbo 6-Speed Manual)
• Subaru Forester XT: 2004, 2005 (2.5L Turbo 5-Speed Manual — Includes Premium)
• Subaru Baja Turbo: 2004, 2005 (2.5L Turbo 5-Speed Manual)
• Subaru Legacy Sport: 1991, 1992, 1993, 1994 (2.2L Turbo 5-Speed Manual)

Mitsubishi

• Mitsubishi Lancer Evolution (Evo VIII & IX): 2003, 2004, 2005, 2006 (2.0L Turbo 4G63T — Fits Base, MR, RS, and SE manual models)
• Mitsubishi Eclipse (GT/GTS): 2000, 2001, 2002, 2003, 2004, 2005 (3.0L V6 6G72 — Fits hardtop and Spyder manual models)

Saab

• Saab 9-2X Aero: 2005 (2.0L Turbo 5-Speed Manual "Saabaru")

Subaru Japanese Domestic Market (JDM)

• Subaru Impreza GT / WRX [JDM]: 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005 (2.0L Turbo EJ20G / EJ205 / EJ207)
• Subaru Impreza WRX STi [JDM]: 2002, 2003, 2004, 2005 (2.0L Turbo EJ207 6-Speed)

The Nameless "Installation" Pro-Tip:

Don't Re-use Your Old Clips (or Skip the Grease): When pulling a transmission apart, never reuse a worn or bent release bearing clip assembly. More importantly, don't skimp on proper lubrication. Apply a light film of high-temperature, high-pressure urea or molybdenum grease directly along the inner groove of the bearing and the transmission's input snout sleeve.

The Golden Rule: Keep grease entirely off the face of the bearing that touches the pressure plate fingers! Too much grease will fling outward under high RPM centrifugal forces, landing right on your clean friction disc, which will instantly glaze your clutch and induce catastrophic slippage. Use it sparingly, keep it clean!