Mazda 3 Brake Master Cylinder Repair

Disassembly and assembly of the Mazda 3 brake master cylinder

If the master cylinder body is damaged, replace the master cylinder assembly.

When fixing the master cylinder in a vise, clamp only the protrusion of the master cylinder

Fig. 1. Components of the main brake cylinder: 1 - cover; 2 - screw; 3 - tank; 4 - bushing; 5 - retaining ring; 6 - piston rod guide; 7 - cup; 8 - limiter; 9 - primary piston; 10, 11 - locking pin and sealing ring; 12 - secondary piston; 13 - master cylinder body

Disassembly

Remove the cap and remove the strainer from the master cylinder reservoir.

Unscrew the fastening screw and remove the tank.

Remove the two O-rings.

Place the cylinder in a vise.

Using a screwdriver, push the pistons all the way through, unscrew the locking bolt and remove the O-ring.

Wrap the screwdriver with plaster or tape to prevent damage to the pistons and cylinder bore.

Fig. 2. Removing the snap ring

Press the piston with a screwdriver and use the circlip pliers to remove the circlip (fig. 2).

Fig. 3. Removing the primary piston with spring

Unscrew the locking piston bolt with gasket and remove the primary piston with the spring, pulling it strictly along the axis without distortion (Fig. 3).

If the piston is removed at an angle, the cylinder bore may be damaged.

Fig. 4. Removing the Secondary Piston

Place a rag on two wooden blocks and lightly strike the cylinder flange against the blocks until the secondary piston comes out.

Make sure that the distance (A) indicated in Figure 4 from the rag to the top of the bars is at least 100mm

Check for rust and scratches on the cylinder mirror.

Inspect the cylinder for wear and damage. If necessary, replace the cylinder.

Replace all parts in the repair kit used to service the brake master cylinder.

When installing, lubricate the rubber parts with clean brake fluid to facilitate assembly.

Do not use factory compressed air to dry or clean brake parts. This may damage the rubber parts.

If any part of the hydraulic system is removed or disconnected, completely bleed the brake system. Perform all repairs on a clean workbench.

Assembly

Install the secondary and primary pistons.

Install a new O-ring onto the retaining screw.

Fully sink the primary piston assembly.

Install and tighten the locking screw. Tightening torque: 2.0 - 2.4 Nm.

Fig. 5. First check of the secondary piston assembly

Press and release the secondary piston assembly, making sure it is held by the locking screw (fig. 5).

Install the secondary piston with the hole facing the stop pin and primary piston.

Install the new O-ring onto the locking pin. Fully sink the primary piston assembly.

Install and tighten the lock pin. Tightening torque: 6.9 - 9.8 Nm.

Fig. 6. Second Check of the Secondary Piston Assembly

Press and release the secondary piston assembly, making sure it is held by the locking screw (fig. 6).