Fitment Information: This ACT Performance Street Sprung Disc fits 2004 - 2021 Subaru STI and 2007 - 2009 Subaru Legacy GT Spec B. It's a replacement for ACT SB4 part numbers. Features: If your ACT Performance Street Sprung Replacement Disc for the Subaru STI (3000503) is worn out and you don't want to splurge on a new clutch kit, get this replacement! The ACT street performance spring replacement disc is made of premium organic materials with high copper content, which allows for better heat transfer. These discs enable quicker shifting and smooth engagement. They have a reduced marcel for faster shift action to pair well with ACT pressure plates. The ACT spring - centered assemblies use bushings and cone springs like factory clutch discs, creating frictional dampening that improves clutch life and reduces noise. It offers quiet operation with increased strength and reliability. Feel: Smooth engagement, quicker shifts, with OE to mild gear rattle. Recommended Use: Ideal for both street and race use. ACT Difference: Steel - backed linings for higher burst strength and a reduced marcel for quicker shifts. Manufacturer Warranty: Limited Retail Warranty. Installation Instructions: Follow ACT's General Installation Instructions. FAQ: Can an ACT Race puck - style disc be used for daily driving? ACT's race discs are very aggressive and offer a no - nonsense performance response. The engagement is harsh, and taking off from a stop may cause judder and an uncomfortable noise. They should only be used in a professional race setting, not on the street. ACT recommends using an organic disc on the street for smoother engagement and longer - lasting performance. When should a clutch disc be replaced? Most new discs are 0.312 - 0.315 inches (7.93 - 8.00 mm) thick, and fully worn is 0.275 inches (7.00 mm) or below. Some applications (mostly Audi and BMW) start at 0.332 - 0.335 inches (8.43 - 8.50 mm) and should be replaced below 0.295 inches (7.50 mm). Measure with a micrometer. Puck discs are measured as is, while organic street discs are measured by fully compressing the engagement cushion between the linings. If the lining rivets on either side of the disc touch the flywheel or pressure plate face, replace the disc. Using a disc outside the pressure plate's working range can lead to poor results.
Using your ACT Performance Street Sprung Disc is straightforward. First, make sure to follow ACT's General Installation Instructions during installation. This disc is great for both street driving and racing. When you're on the road, enjoy the smooth engagement and quick shifting it offers. For maintenance, regularly check the thickness of the disc. Use a micrometer to measure it. If the disc reaches the worn - out thickness levels (0.275 inches or 7.00 mm for most, and 0.295 inches or 7.50 mm for some Audi and BMW applications), it's time to replace it. Also, keep an eye on the lining rivets. If they touch the flywheel or pressure plate face, replace the disc right away. Remember, don't use an ACT Race puck - style disc for daily driving. It's too aggressive for street use and can cause an uncomfortable driving experience. Stick to the organic disc for your daily commutes to get the best performance and durability.
