GMC 1989 Light Duty Truck Repair Manual page 319

The following notice applies to one or more steps in the assembly procedure of components in this portion of the
manual as indicated at appropriate locations by the terminology NOTICE: See 'Notice' on page 5-1 of this section.
NOTICE: This fastener is an important attaching part in that it could affect the performance of vital components and
systems, and/or could result in major repair expense, It must be replaced with one of the same part number or with
an equivalent part if replacement becomes necessary. Do not use a replacement part of lesser quality or substitute
design. Torque values must be used as specified during reassembly to assure proper retention of this part.
SUBJECT
Hydraulic B o o s te r................................................................................................................................................................ 5 - 1
Bendix Hydro-Boost..........................................................................................................................................................5 - 1
Master C ylin d ers.................................................................................................................................................................. 5 - 4
Composite Master Cylinder............................................................................................................................................. 5 - 4
Cast Iron Master C y lin d er............................................................................................................................................... 5 - 4
Bendix Master C ylinder................................................................................................................................................... 5 - 6
Vacuum Boosters.................................................................................................................................................................. 5 - 9
Single Diaphragm Vacuum Booster.................................................................................................................................. 5 - 9
Tandem Diaphragm Vacuum B o o s te r.............................................................................................................................. 5-11
Specifications.........................................................................................................................................................................5-14
Special T o o ls .........................................................................................................................................................................5-15
BENDIX HYRDO-BOOST
Remove or Disconnect (Figure 1)
Bendix Hydro Boost Model has identifying information
stamped into the housing near the inlet line.
C A U TIO N: The a c c u m u la to r
compressed gas. Always use proper tools and
follow recommended procedures or personal
injury may resu lt. Do not apply heat to
accumulator. Do not attem pt to repair an
inoperative accumulator, always replace with a
new accumulator. Dispose of an inoperative
accumulator by drilling a 1 /ie-inch diameter hole
through the end of the accum ulator can
opposite the " O" ring.
Tools Required:
J 26889 Accumulator Compressor
• Place J 26889 over the end of the accumulator and
install a nut onto the stud (figure 2).
• Depress the accumulator with a C-clamp.
• Insert a punch into the hole on the housing.
1. Retainer (1).
• Release the C-clamp.
• Remove J 26889.
2. Accumulator (2) and O-ring (3).
3. Retainer (4).
4. Plug (5), O-ring (6) and spring (7) (figure 3).
SECTION 5
BRAKES
CONTENTS
HYDRAULIC BOOSTER
c o n tain s
S3
I ?
Retainer (26).
Output pushrod (28), baffle (27), piston return spring
(25) and retainer (24).
Saw off the eyelet of the pedal rod (20).
7. Boot (19).
8.
Nut (18) and bracket (17).
9. Bolts (9).
• Separate the cover (16) from the housing (8).
10
. Seals (14 and 15).
11 .
Piston assembly (22) and seal (23).
12
Spool valve (13).
.
13. Accumulator valve (11) (figure 4).
• Make a wire hook to aid in the removal.
14. Return line fitting (12) and seal (10).
Clean
All the parts with power steering fluid.
Inspect
Spool valve and spool valve bore for corrosion, nicks
and scoring. If found, replace the complete booster.
Discoloration of the spool or bore is not harmful and
is no cause for replacement.
Housing and cover sealing surface for corrosion, or
nicks.
Tube seat in the housing for burrs, nicks or
corrosion. Replace if needed (figures 5 and 6).
5-1
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