2CV brake master cylinder: principle and operation
The master cylinder plays a key role in transmitting the hydraulic pressure needed to operate a vehicle's brakes. When the driver presses the brake pedal, it applies force to the piston of the 2CV master cylinder, to which it is directly connected. This force compresses the brake fluid inside the cylinder, creating hydraulic pressure. This pressure is then transmitted by the brake fluid to the vehicle's
front and rear brake systems. The master cylinder therefore converts the mechanical pressure of the pedal into hydraulic pressure in the brake circuit, enabling the friction components (drums or discs) to be activated.
Some master cylinder models are equipped with a single piston and are called ‘single-circuit master cylinders’, while others have two pistons (dual-circuit master cylinders). The presence of two pistons ensures better distribution between front and rear braking thanks to greater hydraulic pressure at the front of the vehicle. It also provides added safety: if one piston malfunctions, there is still a second piston to ensure braking action.
The 2CV master cylinder: several models for different generations of 2CVs
Like the braking system, the master cylinder of the 2CV has evolved significantly throughout the history of the famous Citroën. The models differ mainly in the following ways:
- The mounting point: originally mounted on the
chassis until 1967, the 2CV brake master cylinder was then mounted directly on the
body of the vehicle.
- The number of circuits: after single-circuit 2CV master cylinders until 1978, Citroën subsequently adopted dual-circuit master cylinder models for both 2CVs equipped with front drum brakes and front disc brakes.
- The seal system: the first generations of 2CVs had copper seals until 1967, before switching to red rubber seals for 2CVs requiring Lockheed Dot 4 brake fluid and green rubber seals for those requiring LHM fluid.
- The diameter of the rigid pipes or brake hoses in the
braking system: different diameters were used between 1948 and 1990, changing from 12 mm when the 2CV was launched to 9 mm from 1963 and then to 8 mm after 1973.
- The model of
brake pedal 2CV: round pedal for models up to 1967 with a compass system to interact with the master cylinder then fixed to the chassis. Rectangular brake pedal for all models after 1967, with the pedal/master cylinder connection made by means of a long control rod for single-circuit master cylinders (until 1978) and then a shorter rod for ‘double-circuit’ models (from 1978 to 1990).
To select the master cylinder reference that is perfectly suited to your 2CV, please consult the
dedicated page in our technical library (in French). There you will find a summary table with all the necessary information according to the model year of your car.
Numerous accessories and peripheral parts for the 2CV master cylinder
Single or double reservoir brake fluid tanks, single or dual circuit brake fluid tanks, long or short master cylinder control rods, reservoir seals, mounting spacers, sealing plates,
2CV brake master cylinder bellows and fixing bolts are among the many peripheral spare parts and accessories that you can also order on this page, whether to repair the master cylinder or optimise its performance.
Please feel free to consult our other sections dedicated to 2CV brakes: front brakes,
rear brakes, handbrakes, brake circuits and pedal assemblies.
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