This ACT 4-Puck Rigid Race Disc (4240018) is a top - notch race disc crafted from high - quality ceramic friction materials. It's designed to fit multiple Subaru models, including the 2006 - 2021 WRX, 2004 - 2021 STI, 2005 - 2012 Legacy GT, 2005 - 2009 Outback XT, and 2006 - 2008 Forester XT. Note that it's a 240mm upgrade, and you must use an ACT 240mm pressure plate and flywheel. With a harsher disc engagement, it enables lightning - fast shifting. It features top - grade rivets for secure fastening, carefully selected for maximum strength. This 4 - pad rigid race disc is perfect for smaller engines with smaller disc sizes. The feel is aggressive, offering the quickest shifts but with increased gear rattle. It's strictly for race use. Compared to typical organic materials, it has high burst strength and can hold 28% more torque. Don't use this race disc for daily driving as it has a harsh engagement that can cause judder and noise when starting from a stop. For street use, ACT recommends an organic disc for smoother engagement and longer - lasting performance. To know when to replace the clutch disc, most new discs are 0.312 - 0.315 inches (7.93 - 8.00mm) thick, and fully worn is 0.275 inches (7.00mm) or less. Some applications start at 0.332 - 0.335 inches (8.43 - 8.50mm) and should be replaced below 0.295 inches (7.50mm). Measure with a micrometer. Puck discs are measured as they are, while organic street discs need the engagement cushion compressed. Replace the disc if the lining rivets touch the flywheel or pressure plate face. Using a disc outside the pressure plate's designed working range can lead to poor results.
Using the ACT 4 - Puck Rigid Race Disc is straightforward but requires attention to a few details. First, make sure your Subaru model is one of the compatible ones: 2006 - 2021 WRX, 2004 - 2021 STI, 2005 - 2012 Legacy GT, 2005 - 2009 Outback XT, or 2006 - 2008 Forester XT. Since it's a 240mm upgrade, always use an ACT 240mm pressure plate and flywheel. This disc is only for race use. If you try to use it for daily driving, you'll notice a harsh engagement, which can cause judder and noise when starting from a stop. For normal street driving, switch to an organic disc. To check if the clutch disc needs replacement, use a micrometer. Most new discs are 0.312 - 0.315 inches thick, and when they're 0.275 inches or less, it's time to replace. For some specific models, start at 0.332 - 0.335 inches and replace below 0.295 inches. When measuring puck discs, just measure as they are. For organic street discs, compress the engagement cushion first. Also, if the lining rivets on the disc touch the flywheel or pressure plate, replace the disc right away. And remember, using a disc that's too thick or thin for the pressure plate's designed range can give bad results. Keep these things in mind, and your race disc will serve you well on the track.
