Chevrolet 1977 10 Series, Repair Manual, Page: 167 / 468

BRAKES 5-1
SECTION 5
BRAKES
The following caution applies to one or more steps in the assembly
procedure of components in this portion of the m anual as indicated at
appropriate locations by the terminology "See C aution on page 1 of this
section".
CAUTION: THIS FASTENER IS A N IM P O R TA N T
ATT A C H IN G P A R T I N TH A T I T COULD AFFECT THE
PERFORM ANCE OF VITAL COMPONENTS A N D SYSTEMS,
A N D /O R COULD RESU LT I N MAJOR REPAIR EXPENSE. I T
M U STBE REPLA CED W ITH ONE OF THE SA M E PAR TNU M BER
OR W ITH A N EQ U IVALEN T P A R T IF REPLACEM EN T
BECOMES NECESSAR Y. DO N O T USE A REPLA CEM ENT PAR T
OF LESSER Q U A LITY OR SUBSTITUTE D E SIG N TORQUE
VAL UES M U ST BE USED A S SPECIFIED D U RIN G REASSEMBL Y
TO ASSU RE PROPER R ETEN TIO N OF THIS PART.
CONTENTS
Delco Tandem Power Brake U n it..............................................................5-1
Bendix Tandem Power Brake U n it............................................................5-8
Delco Single D iaphragm Power Brake U n it............................................5-12
Bendix Single D iaphragm Power Brake U n it..........................................5-19
Bendix Hydro-Boost Power U n i t .............................................................. .5-23
DELCO TANDEM POWER BRAKE UNIT
UNIT REPAIR
Disassembly (Fig. 5-1 A)
NOTE:
Scribe a line across front and rear housings to
facilitate reassembly.
1. A ttach base of H olding Fixture J-22805 to front
housing with nuts and washers and draw down tight to
eliminate dam age to studs. Clam p base in a bench vise with
the power section up (fig. 5-2A).
2. Separate front and rear housings as follows:
a.
Straight Mounting Bracket (Fig. 5-2A)
- Place
Spanner W rench J-9504 over studs on rear housing and
attach with nuts and washers. D raw nuts down tight to
elim inate bending or damaging of studs.
b.
Tilt Mounting Bracket (Chevelle)
- Secure
Spanner W rench J-9504 to bracket with three bolts and nuts.
D raw nuts down tight to eliminate damage to bracket.
c.
Tilt Mounting Bracket Except Chevelle
- Place
Tool J-22893 inside tilted m ounting bracket. Place Spanner
W rench J-9504 on top of J-22893 and tighten nuts and
washers, securing spanner wrench.
d. Press down on Spanner W rench J-9504 and rotate the
rear housing counterclockwise to separate the two housings.
CAUTION: Care must be exercised not to damage
or loosen studs in housing. Also, take care that no
pressure is brought to bear on plastic power piston.
3. Remove Tools J-9504 and J-22893 from rear housing
(tilted m ounting bracket type), Tool J-9504 on regular type.
Front Housing Group
1. Remove the power piston return spring. Remove and
discard the vacuum check valve and grommet from the front
housing.
2. Remove the front housing seal.
Rear Housing Group
1. Remove the boot retainer and boot from the rear
housing. Remove the felt silencer from inside the boot.
3. Remove the power piston group from the rear housing
and remove the prim ary power piston bearing from the center
opening of the rear housing.
Power Piston Group
1. Remove the piston rod retainer and piston rod from
the secondary piston.
NOTE:
D ue to an optional construction design on the
prim ary and secondary power pistons, Tool J-23101 will
have to be reworked as shown in Figure 5-3A.
2. M ount double-ended Tool J-23101 (with large
diam eter end up) in a vise. Position the secondary power
piston so that the two radial slots in the piston fit over the
ears (tangs) of the tool (fig. 5-4A).
3. Fold back prim ary diaphragm from the O.D. of the
prim ary support plate. G rip the edge of the support plate and
rotate counterclockwise to unscrew the prim ary power piston
from the secondary power piston.
NOTE:
It is possible th at the prim ary support plate will
unlock from the prim ary piston before the prim ary
piston unscrews from the secondary piston. If this
happens, continue to turn the prim ary support plate
counterclockwise. Tabs (stops) on the prim ary support