torque CHEVROLET DYNASTY 1993 Workshop Manual

material, (Fig. 7). Be sure inboard brake shoe assem-
bly is correctly positioned against anti-rattle clip
(Fig. 6). (4) Reinstall the Braking Disk on the hub, by in-
stalling it over the wheel studs until it is seated
against the face of the hub (Fig. 6). (5) Slide the new outboard brake shoe assembly on
the adapter abutment, (Fig. 5). (6) Carefully lower caliper over the braking disk and
brake shoe assemblies (Fig. 3). Make sure that the
caliper guide pin bolt, bushings and sleeves are clear of
the adapter. (7) Install the caliper guide pin bolts and tighten to
34 to 37 N Im (25 to 35 ft. lbs.). Extreme caution
should be taken not to cross the threads of the
caliper guide pin bolts. (8) Install the wheel and tire assembly. Tighten the
wheel mounting stud nuts in proper sequence (Fig. 9)
until all nuts are torqued to half specification. This is
important. Then repeat the tightening sequence to the
full specified torque of 129 N Im (95 ft. lbs.).
(9) Remove jackstands or lower hoist. Before mov-
ing vehicle, pump the brake pedal several times
to insure the vehicle has a firm brake pedal to
adequately stop vehicle. .
(10) Road test the vehicle and make several stops to
wear off any foreign material on the brake linings and
to seat the brake shoe linings.
Fig. 8 Remove Or Replace Anti-Rattle Clip
Fig. 9 Tightening Wheel Nuts
Ä BRAKES 5 - 37

iper, by installing retaining clip into the bore of the
piston (Fig. 5).
CAUTION: Use care when installing the caliper as-
sembly onto the steering knuckle, so the seal on the
sealed for life bushings does not get damaged.
(5) Carefully lower caliper over braking disc and
guide holddown spring under machined abutment on
knuckle assembly (Fig. 8).
(6) Install caliper guide pin bolts and tighten to
24-34 N Im (18-25 ft. lbs.) torque. When installing guide pin bolts, use extreme caution not to cross
thread the guide pin bolts.
(7) Install wheel and tire assembly. Tighten stud
nuts in proper sequence until all nuts are torqued to
half specification. This is important. Then repeat
sequence to full specification. (8) Remove jackstands or lower hoist. Before mov-
ing vehicle be sure it has a firm pedal, pump
pedal several times. (9) Road test vehicle and make several stops to
wear off any foreign material on the brakes and
to seat the linings.
DISC BRAKE CALIPER DISASSEMBLY
CLEANING AND INSPECTION
Check for piston fluid seal leaks (brake fluid in and
around boot area and inboard lining) and for any
ruptures of piston dust boot. If boot is damaged, or fluid
leak is visible, disassemble caliper assembly and in-
stall a new seal and boot,(and piston if scored). Refer to
procedures titled Disc Brake Caliper Disassembly. Check the caliper dust boot and caliper pin bushings
to determine if they are in good condition. Replace if
they are damaged, dry, or found to be brittle. Refer to
Cleaning And Inspection Of Brake Caliper. (1) Remove caliper from braking disc (See Brake
Shoe Removal). Hang assembly on a wire hook away
from braking disc, so hydraulic fluid cannot get on
braking disc (See Fig. 3 in Brake Shoe Removal). Place
a small piece of wood between the piston and caliper
fingers. (2) Carefully depress brake pedal to hydraulically
push piston out of bore. (Brake pedal will fall away
when piston has passed bore opening.) Then prop up
the brake pedal to any position below the first inch of
pedal travel, this will prevent loss of brake fluid from
the master cylinder. (3) If both front caliper pistons are to be removed,
disconnect flexible brake line at frame bracket after
removing piston. Plug brake tube and remove piston
from opposite caliper. Using the same process as above
for the first piston removal.
WARNING: UNDER NO CONDITION SHOULD AIR
PRESSURE BE USED TO REMOVE PISTON FROM
CALIPER BORE. PERSONAL INJURY COULD RE-
SULT FROM SUCH A PRACTICE.
(4) Disconnect brake flexible hose from the caliper.
To disassemble, mount caliper assembly in a vise
equipped with protective jaws.
CAUTION: Excessive vise pressure will cause bore
distortion and binding of piston.
Fig. 7 Installing Outboard Shoe Assembly onto Cali- per
Fig. 8 Guiding Holddown Spring Under MachinedAbutment
5 - 40 BRAKES Ä

7) until the one end of the bushing is fully seated
into the seal groove on the one end of the sleeve. (3) Holding the sleeve in place work the other end
of the bushing over the end of the sleeve and into the
seal grove (Fig. 8). Be sure the other end of the bush-
ing did not come out of the seal grove in the sleeve. (4) When the sleeve is seated properly into the
bushing. The sealed for life bushing can be held be-
tween your fingers and easily slid back and forth
without the bushing seal unseating from the sleeve. Before installing caliper assembly on vehicle, inspect
braking disc. If any conditions as described in Check-
ing Braking Disc for Runout and Thickness are present
the braking disc, must be replaced or refaced. If the
braking disc does not require any servicing, install
caliper assembly. Install brake hose onto caliper using banjo bolt.
Torque the brake hose to caliper assembly banjo bolt to
33 N Im (24 ft. lbs.). New seal washers MUST al-
ways be used when installing brake hose to cali-
per. Bleed the brake system (see Bleeding Brake System).
Fig. 7 Installing Caliper SleevesFig. 8 Installed Caliper Bushing Sleeve
5 - 44 BRAKES Ä

each brake shoe assembly is returned to its origi-
nal position on the wheel of the vehicle from
which it was removed. (2) Install inboard brake shoe by inserting shoe
retaining clip into piston cavity. Be sure brake shoe is
seated squarely on the face of the piston. (Fig. 5). (3) Install outboard shoe by sliding retaining clip
over caliper fingers. Be sure the brake shoe is installed
on the caliper, so the retaining clip is past the raised
area on the caliper fingers (Fig. 6). (4) Install lower end of caliper on to adapter. Make sure the lower tabs on the brake shoes and the cast-
ing projections on the caliper are under the adapter
rail (Fig. 7). (5) Rotate caliper down over rotor.
(6) Install caliper attaching bolts and tighten to 22
N Im (193 in. lbs.) torque (Fig. 8).
(7) Install wheel and tire assembly. Tighten stud
nuts in proper sequence until all nuts are torqued to
half specification. This is important. Then repeat
sequence to full specification. (8) Remove jackstands or lower hoist. Before mov-
ing vehicle be sure it has a firm pedal.
Fig. 5 Remove and Install Inboard Brake Shoe
Fig. 6 Installing Outboard Shoe
Fig. 3 Removing Caliper
Fig. 4 Removing Outboard Shoe
Ä BRAKES 5 - 47

seal grove (Fig. 13). Be sure the other end of the
bushing did not come out of the seal grove in the sleeve.(4) When the sleeve is seated properly into the
bushing. The sealed for life bushing can be held be-
tween your fingers and easily slid back and forth
without the bushing seal unseating from the sleeve. Before installing caliper assembly on vehicle, inspect
braking disc. If any conditions as described in Check-
ing Braking Disc for Runout and Thickness are present
the braking disc, must be replaced or refaced. If the
braking disc does not require any servicing, install
caliper assembly. Install brake hose onto caliper using banjo bolt.
Torque the brake hose to caliper assembly banjo bolt to
33 N Im (24 ft. lbs.). New seal washers MUST al-
ways be used when installing brake hose to cali-
per. Bleed the brake system (see Bleeding Brake System).
Pump the brake pedal several times to be sure that the
vehicle has a firm pedal, before the vehicle is moved or
driven.
Fig. 13 Installed Caliper Bushing Sleeve
5 - 52 BRAKES Ä

knuckle. Position stem so it contacts hub face near
outer diameter. Care must be taken to position stem
outside the stud circle but inside the chamfer on the
hub rim. Clean hub surface before checking. (See
Fig. 3)
Runout should not exceed 0.08 mm (0.003 inch). If
runout exceeds this specification, hub must be re-
placed. See Suspension Group 2. If hub runout does
not exceed this specification, install disc on hub with
chalk marks two wheel studs apart (Fig. 4). Tighten
nuts in the proper sequence and torque to specifica-
tions. Finally, check runout of disc to see if runout is
now within specifications. If runout is not within specifications. Install a new
braking disc or reface disc, being careful to remove
as little as possible from each side of disc. Remove
equal amounts from each side of disc. Do not reduce
thickness below minimum thickness cast into the un-
machined surface of the rotor. Thickness variation measurements of disc should
be made in conjunction with runout. Measure thick-
ness of disc at 12 equal points with a micrometer at
a radius approximately 25.4 mm (1 inch) from edge
of disc (Fig. 5). If thickness measurements vary by
more than 0.013 mm (0.0005 inch) disc should be re-
moved and resurfaced (Figs. 6 and 7), or a new disc
installed. If cracks or burned spots are evident in the
disc, disc must be replaced. Light scoring and/or wear is acceptable. If heavy
scoring or warping is evident, the disc must be refin-
ished or replaced (See Refinishing/Refacing Braking
Disc). If cracks are evident in the disc, replace the
disc.
BRAKING DISC REMOVAL
(1) Raise vehicle on hoist or jackstands. Remove
wheel and tire assembly. (2) Remove caliper assembly, as described under
Brake Shoe Removal in this Group, (but do not dis-
connect brake line). Suspend caliper from wire hook
or loop to avoid strain on flexible hose. (3) Remove braking disc from the hub.
INSTALLING BRAKING DISC
(1) Slide braking disc on hub. Clean both sides of
braking disc with alcohol or suitable solvent. (2) Install caliper assembly, as described in Brake
Shoe Installation paragraph.
Fig. 2 Marking Braking Disc and Wheel Stud
Fig. 3 Checking Hub for Runout
Fig. 4 Index Braking Disc and Wheel Stud
5 - 54 BRAKES Ä

INSTALLING PARKING BRAKE SHOES
(1) Install rear parking brake shoe and holddown
clip (Fig. 6). (2) Install lower parking brake, shoe to shoe re-
turn spring (Fig. 7). (3) Pull forward parking brake shoe over anchor
block until properly located on adapter. (4) Install upper parking brake, shoe to shoe re-
turn spring (Fig. 8). (5) Install parking brake shoe adjuster assembly
with star wheel forward (Fig. 9). (6) Install front, parking brake shoe holddown clip
(Fig. 10). (7) Adjust parking brake shoes to a diameter to
171 mm (6.75 inch). (8) Install hub assembly on spindle.
(9) Install outer bearing, thrust washer and nut.
(10) Tighten wheel bearing adjusting nut to 27 to
34 N Im (240 to 300 in. lbs.) torque while rotating
hub. This seats the bearings. (11) Back off adjusting nut 1/4 turn (90É) then
tighten adjusting nut finger tight. (12) Position lock on nut with one pair of slots in
line with cotter pin hole. Install cotter pin. (13) Install grease cap.
(14) Install rear braking disc.
(15) Install rear, disc brake caliper on the adapter
(See Brake Shoe Removal).
Fig. 3 Removing Upper Spring
Fig. 4 Removing Shoe and Lower Spring
Fig. 5 Removing Rear Holddown Clip and Shoe
Fig. 6 Installing Rear Shoe and Hold-Down Clip
5 - 64 BRAKES Ä

INSTALLING MASTER CYLINDER
Position master cylinder over studs of power brake
unit, align push rod with master cylinder piston. Install the master cylinder to power brake unit
mounting nuts (Fig. 4) and tighten to 28 N Im (250 in.
lbs.) torque. Connect brake tubes to master cylinder primary and
secondary ports. Tighten fittings to 17 N Im (145 in-
.lbs.) torque.
POWER BRAKES
GENERAL INFORMATION
All vehicles, except non turbo charged AP bodies,
equipped with manual transmissions use a 205 mm
tandem booster. The non turbo charged manual trans-
mission equipped AP body application use a 230 mm
non-tandem booster. The purpose of the vacuum operated power brake
booster. Is to reduce the amount of force applied to the
brake pedal by the drivers foot. To obtain the required
hydraulic pressure in the brake system to stop the
vehicle. The power brake booster can be identified if required,
by the tag attached to the body of the booster assembly
(Fig. 1). This tag contains the following information.
The production part number of the power booster
assembly, the date it was built and who manufactured
it. The power brake booster assembly is not a
repairable part and must be replaced as a com-
plete unit if it is found to be faulty in any way.
The power booster vacuum check valve is not
repairable but can be replaceable as an assembly. The power brake booster is vacuum operated. The
vacuum is supplied from the intake manifold on the
engine through the power brake booster check valve
(Fig. 2). As the brake pedal is depressed, the power boosters
input rod moves forward. This opens and closes valves
in the power booster, creating a vacuum on one side of
a diaphragm and allowing atmospheric pressure to enter on the other. This difference in
pressure forces the output rod of the power booster
out against the primary piston of the master cylin-
der. As the pistons in the master cylinder move for-
ward this creates the hydraulic pressure in the brake
system. Different systems and engine combinations require
different vacuum hose routings.
Fig. 6 Bleeding Master Cylinder
Fig. 1 Power Brake Booster Identification
5 - 68 BRAKES Ä

(7) Unfasten brackets on steel heater water line at
dash panel and left frame rail. On Manual Transmis-
sion vehicles, unfasten clutch cable bracket at shock
tower and move aside. (8) Slide the power brake unit up and to the left
(mounting holes are slotted) on the dash panel, then
tilt inboard and up to remove.
CAUTION: Do not attempt to disassemble power
brake unit as this booster is serviced ONLY as a
complete assembly.
INSTALL (1) Position power brake booster onto dash panel.
(2) Install and tighten the 4 power brake booster to
dash panel mounting nuts (Fig. 5) to 29 N Im (250 in.
lbs.) torque. (3) Install steel heater water line and clutch cable
bracket, if so equipped. (4) Carefully position master cylinder on power
brake unit. (5) Install and tighten the 2 master cylinder to
power booster mounting nuts (Fig. 4) to 29 N Im (250
in. lbs.) torque. (6) Connect vacuum hose onto the check valve, lo-
cated on the power brake unit. (7) Using lubriplate, or equivalent, coat the bearing
surface of pedal pin (Fig. 5). (8) Connect power brake booster input rod to brake
pedal pin and install a NEW retainer clip. Use only a
new retainer clip DO NOT USE the old clip. (9) Check stop light operation.
WHEEL BEARINGS
FRONT WHEEL BEARINGS
Front wheel drive vehicles are equipped with per-
manently sealed front wheel bearings. There is no
periodic lubrication or maintenance recommended for
these units. However if during servicing of the brake
system, service to the front wheel bearing is required
refer to Group 2, Suspension in this service manual.
REAR WHEEL BEARINGS
NORMAL SERVICE
The lubricant in the rear wheel bearings should be
inspected whenever the hubs are removed to inspect
or service the brake system. Or at least every 30,000
miles (48,000 km). The bearings should be cleaned
and repacked with a High Temperature Multipurpose
E.P. Grease whenever the disc brake rotors are re-
surfaced.
INSPECTION
Check lubricant to see that it is adequate in quan-
tity and quality. If the grease is low in quantity, con-
tains dirt, appears dry or has been contaminated
with water, it will appear milky. The bearings then must be cleaned and repacked.
Do not add grease to
a wheel bearing that already has grease packed
in it. Relubricate completely. Mixing of different
types of greases in wheel bearings should be
avoided since it may result in excessive thinning
and leakage of the grease.
REMOVAL AND INSTALLATION
For the servicing, removal and installation of the
rear wheel bearings follow the procedure listed below. (1) Remove the rear tire and wheel assembly.
(2) On rear disc brake equipped vehicles remove the
caliper and rotor. Support the caliper out of the way.
Do not allow the caliper to hang by the hydraulic
hose. See disc brake section in this group for caliper
removal procedure. (3) Remove grease cap, cotter pin, nut lock, nut,
thrust washer and outer wheel bearing. (4) Carefully slide hub or drum from spindle. Do not
drag inner bearing or grease seal over stub axle
(thread, bearing, and oil seal may be damaged.) Using
an appropriate tool remove the grease seal and inner
bearing from the drum or hub. Discard grease
Fig. 5 Power Brake Booster Mounting
5 - 70 BRAKES Ä

WARNING: FAILURE TO DE-PRESSURIZE THE AC-
CUMULATOR PRIOR TO PERFORMING THIS OPER-
ATION MAY RESULT IN PERSONAL INJURY
AND/OR DAMAGE TO PAINTED SURFACES. (2) Remove hydraulic assembly accumulator port
plug,located on right hand side of hydraulic assembly
(Fig. 1).
(3) Install pressure gauge to hydraulic assembly
adaptor into accumulator port of hydraulic assembly
(Fig. 2). Then torque adaptor to 10 N Im (7.5 ft. lbs.).
(4) Install adaptor onto the pressure gauge hose
(Fig. 2) and tighten the fitting to 15 N Im (11 ft. lbs.)
torque. (5) Install pressure gauge and hose adaptor assem-
bly onto the adaptor installed in the hydraulic as-
sembly accumulator port. Then install the retaining
clip into the grove on the accumulator port adaptor
(Fig. 2). MAKE SURE THAT THE RETAINING
CLIP IS INSTALLED ON THE ACCUMULATOR
PORT ADAPTOR BEFORE RE-PRESSURIZING
THE HYDRAULIC SYSTEM.
WARNING: BEFORE REMOVING PRESSURE
GAUGE AND ADAPTOR, BE SURE TO DE-PRES-
SURIZE THE HYDRAULIC ASSEMBLY. THEN IN-
STALL AND TIGHTEN ACCUMULATOR PORT PLUG
TO 12 N IM (9 FT. LBS.).
It is not necessary to bleed the hydraulic assembly
or brake system after installation and removal of the
pressure gauge. Unless additional tubes, hoses, or fit-
tings were removed or loosened.
HYDRAULIC ASSEMBLY INTERNAL LEAK
CHECK
If an internal leak is suspected in the ABS hydrau-
lic circuit, Test Gauge, Special Tool 6685 has been
developed to assist in the diagnostics. This fixture
will assist in determining if there is an internal leak;
and if the leak is in the hydraulic unit or the pump
motor assembly. It can be used whether the pump
shuts off or not. Test Gauge, Special Tool 6685 installation and op-
eration procedure is detailed below. Refer to the Hy-
draulic Pressure Performance Test in the 1993
Bendix Anti-Lock 10 Diagnostic Manual for the re-
quired test procedures.
WARNING: FAILURE TO DE-PRESSURIZE THE AC-
CUMULATOR PRIOR TO PERFORMING THIS OPER-
ATION MAY RESULT IN PERSONAL INJURY
AND/OR DAMAGE TO PAINTED SURFACES.
(1) De-pressurize the accumulator by pumping the
brake pedal a minimum of 40 times with the ignition
off. The procedure is fully explained under De-Pres-
surizing Hydraulic Accumulator which is described
earlier in this System Diagnosis Section. (2) Remove wiring harness connector from dual
function pressure switch on bottom of hydraulic as-
sembly. Connect wiring harness from Test Gauge,
Special Tool 6685 into wiring harness connector re-
moved from dual function pressure switch.Fig. 1 Hydraulic Assembly Accumulator Port Plug Location
Fig. 2 Pressure Gauge and Adapter Installed onHydraulic Assembly
5 - 90 ANTI-LOCK 10 BRAKE SYSTEM Ä