Best Time Management Apps (2025) to Boost Work Productivity Xtreme Extra Heavy Duty Sprung Organic Steel Backed Clutch Kit incl. Flywheel. At Xtreme Clutch, we strive to offer a variety of clutch options for each vehicle to ensure a clutch solution is available for every vehicle application. Whether you are modifying a road vehicle or building a race car from scratch, we have the clutch solution for you. Our upgrades are divided into different stages depending on the friction disc material and the number of friction discs. Steel Backed Organic 1T Steel backed discs allow for an even higher burst strength, perfect for street cars occasionally used on the track. Recommended for: Street use and light track use in vehicles with minor engine modifications. Notes: This clutch kit includes a Flywheel