POWER BRAKE BOOSTER
REMOVING THE ORIGINAL
POWER BRAKE BOOSTER:
beginning work, be sure vehicle is parked in a level area and
that wheels are chocked to prevent unintentional movement.
1. Disconnect the ground cable from the
battery. Vent any vacuum from the booster by applying the brakes
several times. You will notice a change to a hard pedal when all
vacuum has been vented.
2. Carefully disconnect hydraulic lines from the master
3. Remove the nuts attaching the master cylinder to the power
4. Separate the master cylinder from the booster mounting studs.
Keep the master cylinder level.
|CAUTION: DO NOT let brake
fluid contact painted surfaces as the fluid will damage paint.
Should fluid get on paint, immediately flush with water.
5. Disconnect vacuum hose(s) from the
6. Working under the instrument panel,
disconnect the power booster rod linkage from the brake pedal.
NOTE: Two-piece rods may
have to be disassembled before the linkage can be removed from
|7. Remove the nuts holding the
power brake booster unit to the firewall.
NOTE: The nuts may be
located under the dash or on the engine side of the firewall.
|8. Rotate the rod linkage if
necessary and guide it through the firewall as you remove the
power booster. Do not force the rod in either
direction as this will damage the hub and reduce the booster’s
core credit value.
9. Remove linkage parts from the original
power booster for installation on the replacement unit.
IMPORTANT: Be sure to
save any spacers or non-riveted mounting brackets since they must
be reused when installing the replacement unit. These parts are
critical to the operation of the replacement power booster.
10. Put the old power booster into carton
to assure proper core credit upon return.
INSTALLING THE POWER
|1. Install linkage from the old unit onto
the replacement unit.
2. Important: Install
spacers, gaskets and/or mounting brackets from the old unit onto
the replacement unit.
3. Rotate the rod linkage as required to
guide it through the firewall and position the replacement power
booster. Do Not force the rod in either
direction as this will damage the hub and void the warranty.
NOTE: Two-piece rods may
have to be reassembled after the replacement booster is
installed in the vehicle.
|4. Install and tighten the power booster
5. Working under the instrument panel,
connect the rod linkage to the brake pedal.
NOTE: Pedal free play should be 1/16"
to 1/4". Adjust pedal stop or stop light switch behind
brake pedal if necessary.
|6. Carefully locate the master cylinder
onto the power booster mounting studs.
7. Install and tighten the master cylinder
- to - booster mounting nuts.
8. Connect the vacuum hoses(s) to the
power brake booster.
|9. Connect hydraulic lines to
the master cylinder with the fittings just snug. While an
assistant applies moderate pressure to the brake pedal loosen
one brake line fitting to let any trapped air bleed from the
connection. Then tighten the fitting before releasing the pedal.
Wait 15 seconds and then repeat the process (including the 15
second delay) for each fitting on the master cylinder. Make sure
the brake fluid reservoir is kept properly filled during and
after this process.
MASTER CYLINDER PUSH ROD
push rod length is essential to reliable braking. If the rod is
too long, it causes the compensating ports in the master
cylinder to be closed off, eventually resulting in brake drag.
If the push rod is too short there will be excessive brake pedal
travel and possibly there will be a groaning noise from the
brake booster. Use the following procedure to check the push rod
CAUTION: Wear protective goggles
when performing the following procedure! Brake fluid
may erupt from the master cylinder with sufficient force to
cause personal injury.
1. Remove the master cylinder reservoir
cap or cover.
2. While an assistant slightly depresses
the brake pedal, watch for fluid to erupt in the reservoir when
the pedal is depressed 3/8" to 1/2". This indicates
correct push rod length. On dual system master cylinder, fluid
may spurt only from the front reservoir.
|3. If the pedal travels more that 1/2"
before master cylinder fluid erupts, the push rod is too short.
If nothing happens no matter how far the pedal is depressed, the
push rod is probably too long.
4. To adjust the push rod length, first
remove the master cylinder from the power booster. Using a pair
of pliers, turn the push rod adjusting nut in to shorten and out
to lengthen the push rod.
5. If the push rod is non-adjustable, use
shims between the master cylinder and power booster to shorten
it. If too short, remove existing shims or remove the push rod
from the booster and replace it with one of the proper length.
|6. Install the master cylinder
onto the power booster and recheck push rod length.
7. Connect the vacuum hose(s) to the power
8. Reconnect the ground cable to the
9. Make sure the braking system works
correctly before moving the vehicle. If the pedal is soft or has
excessive travel, it may be necessary to bleed the entire
|If you have any
questions e-mail firstname.lastname@example.org.