This procedure should not be undertaken on a vehicle equipped with an ALB (Anti-Lock Brake) system, as special tools are required to properly bleed the brakes; it is advisable to take the vehicle to a dealer service department or a repair shop with the necessary tools. Before deciding to overhaul the Brake Master Cylinder, compare the cost of a new or factory rebuilt unit with that of a rebuild kit, noting that the Brake Master Cylinder on a 1990 Legend cannot be rebuilt. The Brake Master Cylinder is located in the engine compartment, mounted to the power brake booster. Begin by removing as much fluid as possible from the reservoir with a syringe, placing rags under the fluid fittings, and preparing caps or plastic bags to cover the ends of the lines once disconnected, taking care to avoid spilling brake fluid, which can damage paint. Loosen the tube nuts at the ends of the brake lines where they enter the Brake Master Cylinder using a flare-nut wrench to prevent stripping the soft metal fittings. Pull the brake lines slightly away from the Brake Master Cylinder and plug the ends to prevent contamination. Disconnect the electrical connector at the Brake Master Cylinder, then remove the nuts attaching the Brake Master Cylinder to the power booster and carefully pull the Brake Master Cylinder off the studs. Before attempting the overhaul, obtain the proper rebuild kit containing necessary replacement parts and any specific instructions. Remove and clean the filter from the reservoir, then pour out any remaining fluid. On Integra models, loosen the reservoir clamp and pull it off the Brake Master Cylinder body; on Legend models, remove the reservoir retaining screw and carefully pry it loose. Remove the plunger rod seal, push in the secondary piston assembly, and remove the snap-ring with snap-ring pliers. Place the cylinder in a vise and use a punch or screwdriver to depress the secondary piston assembly, then remove the stop bolt. Remove the internal components from the cylinder bore in the exact order they were removed, paying attention to the different tension of the two springs. Disassemble the secondary piston sub-assembly by removing the screw that attaches the secondary spring to the piston, and inspect the bore of the Brake Master Cylinder for deep scoring or damage, as this would require a new Brake Master Cylinder. Replace all parts included in the rebuild kit, cleaning reused parts with brake system cleaner or clean brake fluid, and lubricate all parts with clean brake fluid during assembly. After reassembling the secondary piston sub-assembly, reattach the secondary spring and secure it with the screw. Push the assembled components into the bore, install the stop bolt with a new copper washer, and install the snap-ring and a new plunger rod seal. Install the reservoir, tightening the clamp securely on Integra models or ensuring it is pushed all the way down and securing it with the retaining screw on Legend models. Before installing the new Brake Master Cylinder, it should be bench bled by mounting it in a vise and inserting threaded plugs into the brake line outlet holes, filling the reservoir with the recommended brake fluid, and pushing the piston assembly to expel air. Repeat this process until only brake fluid is expelled, ensuring the reservoir remains filled to prevent air introduction. For installation, place the Brake Master Cylinder over the studs on the power brake booster and tighten the attaching nuts finger tight. Thread the brake line fittings into the Brake Master Cylinder, adjusting the position slightly if necessary, and fully tighten the mounting nuts and brake fittings. Fill the Brake Master Cylinder reservoir with fluid, then bleed the Brake Master Cylinder and brake system, having an assistant pump the brake pedal and hold it to the floor while loosening the fitting nut to allow air and fluid to escape, repeating until the fluid is clear of air bubbles, and test the operation of the brake system carefully before placing the vehicle in normal service.
Posted by AcuraPartsWarehouse Specialist 
