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
On manual brake master cylinders
(except some Chrysler products), disconnect the push rod
from the brake pedal linkage under the dash. NOTE: Some Chrysler 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
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. If 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
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
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
3. Install plugs to seal the ports. Plugs are in the kit or
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.
REPLACEMENT MASTER CYLINDER:
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
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
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
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:
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
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
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.