MASTER CYLINDER
Step-by-Step Installation Instructions

REMOVING THE ORIGINAL MASTER CYLINDER:
NOTE: Before beginning to work, be sure vehicle is parked in a level area and that wheels are chocked to prevent unintentional movement. The master cylinder MUST be level during this procedure.

Disconnect the ground cable from the battery.
On manual brake master cylinders (except some Chrysler products), disconnect the push rod from the brake pedal linkage under the dash

NOTE:
Some vehicles use manual brake master cylinders with a “pop-out” pushrod. After removing the flange bolts, support the master cylinder and use a wedge between the flange and firewall to “pop” the pushrod form the piston.

DO NOT separate the pushrod from the brake linkage.
Disconnect electrical lead(s) from master cylinder’s brake failure warning switch, if so equipped.
Clean the area around the brake line connections on the master cylinder.

Disconnect brake lines from the master cylinder and proportioning valves, if so equipped. Cover or plug lines to prevent dirt from entering and contaminating the brake system. CAUTION: DO NOT allow brake fluid to contact painted surfaces as the fluid damages paint. I
f contact occurs, immediately flood the affected area with water.

Remove the nuts/bolts securing the master cylinder to the firewall or power brake booster. DO NOT remove power brake booster.

Remove master cylinder from the vehicle. CAREFULLY remove and save any fittings, gaskets or components (including brake warning switches and proportioning valves) for installation on the replacement unit, if necessary.

NOTE: If the replacement master cylinder is supplied without a reservoir, you must remove and transfer the reservoir from the original master cylinder to the replacement unit.


TRANSFERRING THE RESERVOIR:

CAUTION: BEFORE YOU REMOVE YOUR MASTER CYLINDER RESERVOIR YOU MUST DETERMINE HOW IT IS RETAINED!
If your master cylinder reservoir is retained with a roll pin(s) or screw(s), use the following procedure:

Remove the roll pin(s) or screw(s) attaching the reservoir to the master cylinder.
Remove the reservoir from the master cylinder with the pin(s) or screw(s) removed, the reservoir can be removed easily by hand.
Replace the O-Rings on the reservoir with the new O-Rings supplied.
Install the reservoir on the master cylinder and secure with the roll pin(s) or screw(s).
CAUTION: If the replacement unit has two (2) non-thread holes, use the roll pin(s). If a threaded hole is present, use the screw(s) instead.

NOTE:
If you master cylinder is NOT retained with roll pin(s) or screws, refer to the following procedure:

Carefully drain remaining brake fluid from the master cylinder.

Position the original master cylinder in a vise so the jaws clamp onto the mounting flange. DO NOT TIGHTEN THE VISE JAWS ON THE MASTER CYLINDER BODY! This will cause damage and void the unit’s core value.

Use a wide pry bar or large screwdriver to “pop” the reservoir off the master cylinder.(See Figure Below) Use caution to avoid damaging reservoir.

Remove the reservoir mounting grommets and install them on the replacement unit.

Lubricate the grommets and reservoir necks with clean brake fluid. Carefully press the replacement master cylinder body down onto the reservoir using a slight rocking motion.
Please original master cylinder in replacement carton to assure proper core credit upon return.

BENCH BLEEDING THE MASTER CYLINDER:

NOTE: “Bench bleeding” (removing air from the master cylinder) must be completed BEFORE the replacement unit is installed in the vehicle. Otherwise, the brake pedal will be insufficient and THE WARRANTY WILL BE VOID!

1. Position the replacement master cylinder in a vise so that the jaws clamp onto the mounting flange. DO NOT TIGHTEN THE VISE JAWS ON THE MASTER CYLINDER BODY! This will cause damage and void the warranty.

2. Install brake failure warning switch and proportioning valves, if so equipped, onto the replacement master cylinder BEFORE bench bleeding the unit. Use the new O-rings supplied with the replacement unit on the valves and switch. Install plugs in the proportioning valve ports, if so equipped, before bench bleeding.

3. Install plugs to seal the ports. Plugs are in the kit or reservoir.

4. Use a wooden dowel or similar tool to slowly push the master cylinder piston in about on inch, then release the piston slowly.

CAUTION:
Be careful to avoid spraying brake fluid! Keep your face away from the open reservoir.

5. Wait 15 seconds and repeat step 4 until you no longer see air bubbles in the reservoir.

6. Replace the reservoir cover. Do not remove bleeder plugs from the brake line fittings yet.

NOTE:
Some fluid around the mouth of the piston bore is normal and does not indicate leakage. This is a rust inhibitive bore lubricant used during assembly.

INSTALLING THE REPLACEMENT MASTER CYLINDER:

IMPORTANT:
Your replacement master cylinder is guaranteed to fit and function in its listed applications, even though it may be different in appearance from the original unit.

Install any remaining fittings or components removed from the original unit onto the replacement cylinder.
If the replacement unit is supplied without a pushrod, the original pushrod must be used.

NOTE:
For Chrysler “pop out” style pushrods, remove the original rubber lock piece and replace with new one supplied with replacement kit. Lubricate the fresh brake fluid and “pop” back into new master cylinder piston.

Install sealing ring, gasket or spacer, if necessary, between master cylinder and booster or firewall. THESE PARTS ARE CRITICAL TO THE OPERATION OF THE REPLACEMENT MASTER CYLINDER!

NOTE:
On GM applications using anglemounted master cylinders, the rear of the vehicle must be elevated to bring the master cylinders to a level position. This prevents air from being trapped. When raising the vehicle, use a lift or jack stand. The use of a jack only is very dangerous!

Position the replacement master cylinder on the firewall or over the booster mounting studs.

NOTE:
The master cylinder flange should fully seat on the power booster face without applying pressure to the master cylinder piston. If it does not seat properly, the push rod must be adjusted or replaced (see “Adjusting the Push Rod” section that follows).

Remove temporary plugs from the brake lines. Remove plugs one a time form outlet fittings or proportioning valves and connect brake lines to the master cylinder.

NOTE:
Use the brass adapters supplied with the replacement unit I brake line fittings differ in size form master cylinder ports.
Tighten master cylinder mounting nuts or bolts to the manufacturer’s specification.

Fill the reservoir to the correct level with fresh brake fluid. NEVER reuse brake fluid that has been drained from the system! Replace reservoir cover.

Pedal should be high and firm after the bleeding procedure. If it isn’t bleed the entire hydraulic system using the bleeder screws at the caliper or wheel order and procedure.
NOTE: Check master cylinder fluid level after bleeding each wheel cylinder. DO NOT allow that master cylinder to run out of fluid.

After completing the bleeding procedure, top off the reservoir, if necessary , and replace master cylinder cover.
Re-connect brake failure warning switch lead to master cylinder, if so equipped.

Re-connect the battery ground cable.
Be sure the brake system is working properly before moving the vehicle.

ADJUSTING THE MASTER CYLINDER PUSH ROD:

NOTE: Correct pushrod length is essential to reliable braking. If the push rod is too long, is causes the master cylinder compensating ports to be blocked off, eventually resulting in brake drag.
If the rod is too short, excessive brake pedal travel and, possible, a groaning noise from the power booster will be noticed. Check the adjustment of the push rod using the following procedure.

Remove the master cylinder reservoir cover.
Have an assistant depress the brake pedal slightly. Watch for fluid movement when the brake pedal is depressed 3/8” to ½”. This indicates correct push rod length. On dual system master cylinders, fluid movement may occur in the front reservoir only.

If the pedal travels more the ½” before fluid movement is noticed, the push rod is too short. If nothing happens no matter how far the pedal is depressed, the push rod is too long.

To adjust the push rod’s length, remove the master cylinder from the vehicle. Turn the adjusting nut in to shorten the rod or out to lengthen the push rod.

If the push rod is non-adjustable, use shims between the master cylinder and the firewall or power booster or shorten it. If too short, remove the push rod from the master cylinder or power booster and replace it with one or proper length.
Install the master cylinder and recheck push rod length.