Clutch Master Cylinder

The clutch master cylinder turns force at the pedal into hydraulic pressure that drives the slave cylinder and releases the clutch. The range includes replacement and upgrade master cylinders, a release-system upgrade, and a spacer for fitting another model’s master cylinder to an older chassis.

Master and slave cylinders work as a hydraulic lever, and their bore sizes set its ratio. A smaller master bore gives a lighter pedal but needs more pedal travel to move the slave the same distance, while a larger bore does the opposite. An upgrade cylinder may change the bore, the body or the seals, and any bore change alters effort and travel together.

At rest, the piston must return fully so that a small port to the reservoir opens. This lets the fluid expand with heat and return to the reservoir as the clutch wears. If the pushrod holds the piston forward, the port stays shut, pressure builds as the fluid warms and the clutch can start to slip.

Choose between:

• Replacement or upgrade: a direct replacement restores the factory feel, while an upgrade suits heavier clutches and engine swaps.
• Release-system upgrade: this treats the hydraulic release as a whole rather than as a single cylinder.
• Spacer: for fitting a master cylinder from another model to the chassis named in the title.
• Vehicle: titles give the model and years or the swap, and the line fittings must match too.

Bench-bleed a new master cylinder before fitting, then bleed the whole system from the slave end. Set the pushrod for the small free play the maker specifies, and adjust the clutch pedal switch where the car uses one for starting or cruise control. A leak past the rear seal shows as fluid on the bulkhead or carpet, so check there after the first drives.