Toyota 47028-04030
Master Cylinder

Service and repair of the Brake Master Cylinder (without VSC) requires starting with battery terminal cable removal as well as draining brake fluid and immediate brake fluid cleanup from painted areas. The first step requires the removal of brake master cylinder through disconnecting the brake fluid level warning switch connector. After disconnecting manual transmission vehicles from the clutch reservoir tube you should remove this connection from the reservoir. A union nut wrench is needed to disconnect the 2 brake lines that are attached to the brake master cylinder. First disconnect the brake master cylinder from the 2 nuts and then pull it out of the brake booster space before removing its O-ring.

The brake master cylinder replacement starts with pumping the brake pedal multiple times to vent vacuum from the booster before disconnecting the battery's negative cable and draining the fluid. Then immediately cleanse any touched paint with solvent. The clutch reservoir tube needs to be separated from the reservoir system of manual transmission vehicles before any work can proceed. First disconnect the brake fluid level warning switch connector followed by using a union nut wrench to separate the 2 brake lines from the brake master cylinder sub-assembly, remove the 2 nuts, then extract the brake master cylinder sub-assembly from the brake booster with caution to preserve the O-ring. Keep the master cylinder out of harm to protect its usefulness because a dropped master cylinder cannot be put back into use. Keep the pressure off the master cylinder piston while installation and removal of the sub-assembly by minimizing bending and positioning it horizontally or downward. This arrangement prevents piston detachment. Foreign objects should not come into contact with the master cylinder piston and in case of contamination a clean cloth should be used to remove the foreign matter followed by lithium soap-based glycol grease application around the circumference of the piston pnictle. Different types of grease or fluid must not be used during this process.

Install a new O-ring onto the brake master cylinder and secure it to the brake booster with 2 nuts, torquing to 13 Nm (127 kgf-cm, 9 ft-lbf).

Fill the reservoir with brake fluid, bleed the master cylinder using Special Service Tool: 09023-00101, bleed the brake line, check the fluid level in the reservoir, inspect for brake fluid leakage, and verify the brake pedal height, free play, and reserve distance.

Inspect and adjust the brake booster push rod, ensuring the brake booster interior is not under vacuum by stopping the engine and depressing the brake pedal several times.

Use chalk on the tip of an accessory tool, place it on the brake booster assembly, and measure the clearance, which should be 0 mm (0 inch).