Clutch Slave Cylinder

It can be outside the gearbox or combined with the release bearing inside the bellhousing (concentric slave cylinder). Internal ones usually require gearbox removal to replace. Leaks may appear at the bellhousing. Bleeding a concentric slave cylinder can be tricky; some need pressure bleeding or a specific sequence.

Fluid pushes a piston that moves the release fork or bearing.

Fluid loss, a pedal that stays down or gears that grind indicate a fault. Concentric slave cylinders are often replaced with the clutch.