Buick 18007935 Repair Kit, Brake Mast Cyl

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The first thing to consider is that you should buy a brake master cylinder overhaul kit, which will contain all the replaceable parts important for fluid, especially rubber seal that are used in the operation of this part. Make sure that these parts are properly fixed in place and the correct way around without coming in contact with grease or any mineral based solvent. Recent the brake fluid area of the car and particularly the front fender and cowling section. Remove the brake line connections and put some rag or newspaper beneath the brake master cylinder to soak any dripping fluid. Take out the two mounting nuts, slightly adjust the bracket which retains the combination valve without the need of bending the hydraulic lines and take out the brake master cylinder. Most if not all the fluid in the reservoir should be emptied before lifting the cover along with the diaphragm, but get hold of the primary piston and pull down and remove the lock ring to get the primary piston assembly out gently. Do the same thing for the so-called 'secondary piston assembly'. Mount the brake master cylinder in a vise, as shown, and detach the reservoir from the cylinder body without dissecting the built-in non-serviceable quick take-up valve. Take out the reservoir rubber grommets and examine the cylinder bore for rust and or damage and replace the brake master cylinder body if any. Coat new grommets with silicone brake lube, fully insert them on its respective holes, and put brake master cylinder body to the reservoir with a rocking motion. Remove old seals on the secondary piston assembly and place new ones the cups of which should face outwards before fittings the spring retainer. Clean brake fluid should be used to lubricate the cylinder bore, before you put back the spring and the second piston. Remove the primary piston assembly, grease the new seal, and fit it with the lips turned away from the piston and fit this primary piston assembly into the bore and lock into place using the lock ring. Check up for any cracks or other defects in the hydraulic reservoir cover as well as the diaphragm and repair any of them that are defective. When the brake master cylinder is removed the hydraulic system needs to be bled, this may be done by filling and bench bleeding the brake master cylinder before fitting it. Thread the plugs into the outlet holes, then fill the two reservoirs with brake fluid, then unscrew a single plug while pressing the piston assembly to release the air inside; after which, screw the plug back in before the release of the piston. Gently tap the piston on each of the outlets to ensure that all the air is removed, refill the reservoirs, place the diaphragm and cover back in place but fill only up to the level of the divider as this is the maximum limit of filling. Last, re-fit the brake master cylinder, in the same way as it was removed with bleeding performed at the wheel bleed valves.

Before dismantling, it is advisable to purchase a Brake Master Cylinder overhaul kit that includes all the necessary replacement parts, particularly the rubber seals, to ensure proper fluid control within the Brake Master Cylinder. During the rebuild procedure, be cautious not to allow grease or mineral-based solvents to contact the rubber parts. To protect painted surfaces from brake fluid spills, cover the front fender and cowling area of the car. Start by disconnecting the electrical lead from the brake failure warning switch and then disconnect the brake line connections, using rags or newspapers to soak up the fluid that will drain out. For manual brake setups, disconnect the Brake Master Cylinder pushrod from the brake pedal inside the car. Remove the two Brake Master Cylinder mounting nuts, take out the Brake Master Cylinder from the car, and drain any remaining fluid. Remove the brake failure warning switch and the two proportioner valves, noting their respective positions as they are different. For further disassembly, it is helpful to place the Brake Master Cylinder in a vice with blocks of wood on either side to avoid overstressing the aluminum body. Use an Allen wrench to remove the switch piston plug and extract the switch piston assembly from the bore. Next, remove the primary piston retaining ring and then the primary and secondary piston assemblies. Also, remove the plastic reservoir and the quick take-up valve retaining ring, and clean all parts in denatured alcohol, avoiding gasoline or mineral-based solvents that could damage the rubber seals. Inspect the cylinder bore for any imperfections and use crocus cloth if needed, rinsing the bore with clean brake fluid afterward. Replace the old seals with new ones, lubricate the bore with brake fluid, and reassemble the primary piston assembly. Similarly, disassemble and install new 0-rings and retainers for the switch piston assembly before putting it back into the cylinder. Install new 0-rings on the proportioner valves and the failure warning switch, and insert the quick take-up valve into the cylinder body with its retaining ring. Press new reservoir grommets into the cylinder body, place the reservoir top down on a flat surface, and press the cylinder body onto it with a rocking motion. Install the cylinder on its mounting studs and reconnect the Brake Master Cylinder pushrod (for manual brake setups) and the brake line connections, torquing them to specs. Reconnect the electrical lead to the failure warning switch. Fill the Brake Master Cylinder reservoir with brake fluid and bleed the brake system. Finally, install the reservoir diaphragm and cover, and test drive the car while checking for proper braking performance and leaks.

Remove the brake failure warning switch and the two proportioner valves, noting their respective positions as they are different. Place the master cylinder in a vice with blocks of wood on either side to avoid overstressing the aluminum body. Use an Allen wrench to remove the switch piston plug and extract the switch piston assembly from the bore. Remove the primary piston retaining ring and then the primary and secondary piston assemblies. Also, remove the plastic reservoir and the quick take-up valve retaining ring.

The brake master cylinder is located under the hood, in the left rear section of the engine compartment.

Assemble primary and secondary seals along with the protector. Insert the assembly into the cylinder and seat the spring against the bore.

Use compressed air to force out the secondary piston, spring, and retainer.

Care should be taken not to spill any brake fluid on painted surfaces, as it can eat paint.

Possibly a composite design master cylinder.

To overhaul and install the master cylinder, mount it in a padded vise and remove the primary piston lock-ring by depressing the piston and prying the ring out. Then, remove the primary and secondary piston assemblies, as well as the reservoir and grommets. Inspect the cylinder bore for damage, and if found, replace the master cylinder body. Lubricate and press the new reservoir grommets into place, then attach the master cylinder body to the reservoir using a rocking motion.

With the master cylinder vertical, push the secondary piston into the bore to seat its spring.

Wash them in clean hydraulic fluid, discard all rubber components and the primary piston, and purchase a rebuild kit containing all necessary parts for the overhaul.

Unbolt the isolation/dump valve and RWAL module mounting bracket, then plug the brake line ends to prevent contamination. Remove the two master cylinder mounting nuts and move the bracket aside slightly, taking care not to kink the hydraulic lines. Finally, remove the master cylinder from the vehicle and discard any remaining fluid in the reservoir after removing the reservoir cover and diaphragm.

Drain all fluid from the master cylinder and place the unit in a vise, using wood blocks to cushion the jaws.

Purchasing a master cylinder overhaul kit is important as it includes all the necessary replacement parts, particularly the rubber seals, to ensure proper fluid control within the master cylinder during the rebuild procedure.