Should you replace the clutch when replacing the slave cylinder?

Due to the amount of time involved and the need to remove the transmission to replace the slave cylinder, many technicians will recommend replacing the clutch assembly at the same time as the slave cylinder. If the slave cylinder is leaking fluid, it is also possible that it has already ruined the fibrous friction material on the clutch disc. When that is the case, the clutch assembly needs to be replaced.

What's the difference between the clutch master and slave cylinder?

The clutch master cylinder is a fluid pump operated directly by the action of the driver's foot pressing on the clutch pedal. The clutch slave cylinder, on the other hand, receives pressure through a thin tube from the master cylinder. The slave cylinder converts that hydraulic pressure back into mechanical motion to move the clutch pressure plate inside of the transmission and disengage it from the engine.

-Why do clutch slave cylinders fail?

Slave cylinders go bad simply because they have too many miles on them. But they also fail due to excessive heat from overworked or overheated clutches. That can occur as a result of aggressive or improper use of the clutch pedal when driving. Moisture contamination of the clutch hydraulic fluid can also cause internal corrosion of the slave cylinder and lead to fluid leaks.