All models covered in this manual are equipped with front disc brakes (with solid or ventilated discs) and self-adjusting rear drum brakes, but all later models are fitted with rear disc brakes. Anti-Lock Braking System (ABS) on some models it is a standard equipment item, and on some it is installed as an option (at the request of the client). For more information on the operation of the ABS system, refer to paragraph 19.
The front disc brakes are actuated by single-piston floating calipers that apply equal pressure to each brake pad.
On models with rear drum brakes, each rear brake is equipped with a primary and secondary brake shoe actuated by twin-piston wheel cylinders. The brake has a built-in self-adjusting mechanism to compensate for brake pad wear. As the brake pads wear, pressing the brake pedal automatically activates an adjusting mechanism that increases the effective length of the spacer bar, thus repositioning the brake pads to reduce the clearance between the pads and the drum.
To prevent the rear wheels from locking up during emergency braking, a load-sensing pressure control valve is built into the hydraulic circuit to each rear brake (rear brake pressure regulator). The valve is installed on the bottom at the rear of the car and is connected to the rear suspension by means of a rod and a spring. The valve senses the load placed on the rear of the vehicle by monitoring the movement of the rear suspension and adjusts the hydraulic pressure applied to the rear brakes accordingly. On later models (starting around 2001), equipped with ABS, the hydraulic pressure applied to the rear brakes under all braking conditions is controlled by the ABS hydraulic modulator. These models do not use a separate mechanical pressure control valve.
On all models, the parking brake has an independent mechanical drive and acts on the rear brakes.
On diesel models, intake manifold vacuum is not sufficient to effectively activate the brake booster under all operating conditions. To solve this problem, a vacuum pump is provided that creates a sufficient vacuum for the operation of the vacuum brake booster. The vacuum pump is mounted on the left end of the cylinder head. It is driven directly from the end of the camshaft.
Note. When servicing any part of the system, work carefully and methodically. When carrying out any repairs to the hydraulic system, be absolutely clean. If there is any doubt about the condition of the brake elements, be sure to replace the brake elements at the same time on both wheels of the same axle. Use only genuine Peugeot/Citroen parts, or at least parts of known good quality. Follow the warnings. given in chapter «Safety first!» and in the relevant paragraphs in this chapter and relating to the hazards of asbestos dust and brake fluid.