The clutch master cylinder is located on the firewall typically next to the brake master cylinder and its primary function is to transfer the clutch pedal pressure to release the clutch. You will know if the clutch master cylinder is failing if you rest your foot on the clutch pedal and the pedal slowly goes to the floor. Every clutch master cylinder will be tested strictly for its durability and performance, and only parts conform to OE standards will be sold to the market.