1993 CHEVROLET DYNASTY boot

If old springs have overheated or are damaged, re-
place. Overheating indications are paint discoloration
or distorted end coils. Varga brake springs are not
painted but overheating of the brake springs will be
noted by any Blueing of the springs.
BRAKE SHOE INSTALLATION
Lubricate the eight shoe contact areas on the sup-
port plate and anchor using Mopar Multi-Purpose
Lubricant or equivalent (Fig. 11).
KELSEY HAYES REASSEMBLE
Assemble the park brake lever and wave washer to
the new replacement shoe (Fig. 9). Attach upper return spring between the two new
shoe assemblies. Apply a small amount of Mopar Multi-Purpose Lu-
bricant or equivalent to the automatic adjuster screw
assembly. Install adjuster with the two stepped forks
facing toward the outboard side of the shoes (Fig.
10). The longer fork will be pointing to the rear. Connect the lower shoe to shoe spring. Expand the automatic adjuster so that the end of the
shoes will clear the wheel cylinder boots. Position the
brake shoe assemblies on support plate and install
holddown springs (Fig. 7). Install self adjuster lever and spring.
Connect park brake cable.
Adjust brake shoes so that they will not interfere
with the drum installation.
CAUTION: Make sure the adjuster screw nut contacts
the adjuster tubular strut.
Install the drums and pump the brake pedal
several times to partially complete the shoe ad-
justment. After adjusting the Parking brake cable (see Adjust-
ing Parking Brake), road test vehicle. The automatic
adjuster will continue the brake adjustment during the
test.
VARGA REASSEMBLE
(1) Install park brake cable in park brake lever of
trailing shoe. (2) Attach trailing shoe, then leading shoe lower
springs to shoes and anchor plate. (3) Position shoes on support plate and install hold-
down springs. (4) Install automatic adjusters. Left side adjuster
has left hand threads and right side adjuster has
right-hand threads. Do not interchange sides.
Make sure adjuster is installed correctly. (Adjuster
ends must be above extruded pins in web of shoe as
shown in Fig. 3). (5) Install upper shoe to shoe spring. Ensure that
the spring terminal ends are fully engaged in the shoe
webs. (6) Rotate serrated adjuster nut to remove free play
from the adjuster assembly. (7) Install the adjuster lever on the leading shoe
pivot pin. Then attach the short end of the adjuster
spring into the hole on the lever. Then install the long
end of the spring in the leading shoe hole. (8) Connect park brake cable and adjust brake shoes
so as not to interfere with drum installation.
BRAKE DRUM REFACING
Measure drum runout and diameter. If not to speci-
fication, reface drum. (Runout should not exceed
0.1524 mm or 0.006 inch). The diameter variation (oval
shape) of the drum braking surface must not exceed
either 0.0635 mm (0.0025 inch) in 30É or 0.0889 mm
(0.0035 inch) in 360É. All drums will show markings of maximum allowable
diameter (Fig. 12).
Fig. 10 Adjuster Screw and Lever (Typical)
Fig. 11 Shoe Contact Areas on Support Plate
Ä BRAKES 5 - 21

WHEEL CYLINDERS INDEX
page page
General Information ....................... 23
Installing Wheel Cylinders .................. 24 Service Procedures
....................... 23
GENERAL INFORMATION
The piston boots are of the push-on type and pre-
vent moisture from entering the wheel cylinder. To perform service operations or inspections of the
rear wheel brake cylinders. It will be necessary to re-
move the cylinders from the support plate and disas-
semble on the bench.
CAUTION: Wheel cylinders with cup expanders
must have cup expanders after any service proce-
dures (reconditioning or replacement).
SERVICE PROCEDURES
REMOVING WHEEL CYLINDERS FROM BRAKE SUPPORT PLATES
With brake drums removed, inspect the wheel cyl-
inder boots for evidence of a brake fluid leak. Then
block the brake pedal in the stroke position, and vi-
sually check the boots for cuts, tears, or heat cracks.
If any of these conditions exist, the wheel cylinders
should be completely cleaned, inspected and new
parts installed. (A slight amount of fluid on the boot
may not be a leak, but may be preservative fluid
used at assembly.) (1) In case of a leak, remove brake shoes, (replace
if soaked with grease or brake fluid.) (2) Thoroughly clean area of wheel cylinder, where
hydraulic brake line connects to wheel cylinder. Dis-
connect hydraulic brake tube from wheel cylinder
(Fig. 1). (3) Remove the rear wheel cylinder attaching bolts
(Fig. 1). Then pull wheel cylinder assembly off the
brake support plate (Fig. 2). (4) Clean the surface sealant off the support plate
and wheel cylinder surfaces.
DISASSEMBLING WHEEL CYLINDERS
To disassemble the wheel cylinders, (Fig. 3) pro-
ceed as follows: (1) Pry boots away from cylinders and remove.
(2) Press INon one piston to force out opposite pis-
ton, cup and spring (with cup expanders). Then using
a soft tool such as a dowel rod, press out the cup and
piston that remain in the wheel cylinder. (3) Wash wheel cylinder, pistons, and spring in
clean brake fluid or alcohol; (DO NOT USE ANY
PETROLEUM BASE SOLVENTS) clean thor- oughly and blow dry with compressed air. Inspect
Fig. 1 Brake Tube Disconnected
Fig. 2 Remove or Install Wheel Cylinder
Ä
BRAKES 5 - 23

cylinder bore and piston for scoring and pitting. (Do
not use a rag as lint from the rag will stick to bore
surfaces.) Wheel cylinder bores and pistons that are scored or
pitted in any way should be replaced. Cylinder walls
that have light scratches, or show signs of corrosion,
can usually be cleaned with crocus cloth, using a cir-
cular motion. Black stains on the cylinder walls are
caused by piston cups and will not impair operation
of cylinder.
ASSEMBLING WHEEL CYLINDERS
Before assembling the pistons and new cups in the
wheel cylinders, dip them in clean brake fluid. If the
boots are deteriorated, cracked or do not fit tightly
on the pistons or the cylinder casting, install new
boots. (1) Coat cylinder bore with clean brake fluid.
(2) Install expansion spring with cup expanders in
cylinder. Install cups in each end of cylinder with
open end of cups facing each other (Fig. 3). (3) Install piston in each end of cylinder having
the flat face of each piston contacting the flat face of
each cup, already installed (Fig. 3). (4) Install a boot over each end of cylinder. Be
careful not to damage boot during installation.
INSTALLING WHEEL CYLINDERS
(1) Apply Mopar tGasket In-A-Tube or equivalent
sealant around wheel cylinder mounting surface (Fig.
4). (2) Install wheel cylinder onto brake support, and
tighten the wheel cylinder to brake support plate at-
taching bolts to 8 N Im (75 in. lbs.). (3) Attach hydraulic brake tube to wheel cylinder,
and tighten tube to wheel cylinder fitting to 17 N Im
(145 in. lbs.). (4) Install brake shoes on support plate.
(5) Install rear brake drum onto rear hub. Install
rear wheel and tire assembly, tighten wheel stud
nuts to 115 N Im (85 ft. lbs.).
(6) Adjust the rear brakes, (See Adjusting Service
Brakes) in Service Adjustments section in this group
of the service manual. (7) Bleed the entire brake system. See (Bleeding
Brake System) in Service Adjustments section in this
group of the service manual.
Fig. 3 Rear Wheel Cylinder
Fig. 4 Apply Sealant on Support Plate
5 - 24 BRAKES Ä

A square cut rubber piston seal is located in a ma-
chined groove in the cylinder bore. This provides a
hydraulic seal between the piston and the cylinder
wall (Fig. 6). A molded rubber dust boot is installed in a groove
of the caliper assembly piston bore. This prevents
contamination in the bore area of the caliper assem-
bly. The boot mounts in the cylinder bore opening and
in a groove in the piston (Fig. 6). This prevents con-
tamination in the bore area. As lining wears, master cylinder reservoir brake
fluid level will go down. If brake fluid has been
added to the reservoir, reservoir overflow may occur
when the piston is pushed back into the new lining
position. Overflowing can be avoided in this case by
removing a small amount of fluid from the master
cylinder reservoir. All Vehicles, are equipped with an audible wear
sensor on the outboard pad of the front disc brake as-
Fig. 2 Front Disc Brake Assembly (Non-Family Caliper Typical)
Fig. 3 Disc Brake Caliper Mounting (Family Caliper)
5 - 32 BRAKES Ä

CLEANING AND INSPECTION
Check for piston seal leaks (brake fluid in and
around boot area and inboard lining) and for any
ruptures of the piston dust boot. If boot is damaged,
or fluid leak is visible, disassemble caliper assembly
and install a new seal and boot,(and piston if scored).
Refer to procedures titled Disc Brake Caliper Disas-
sembly. Check the caliper dust boot and caliper pin bush-
ings to determine if they are in good condition. Re-
place if they are damaged, dry, or found to be brittle.
Refer to Cleaning And Inspection Of Brake Caliper.
BRAKE SHOES INSTALL
(1) Thoroughly clean and lubricate both adapter
ways on the steering knuckle, with a liberal amount
of Mopar Multi-purpose Lubricant, or equivalent. (2) The inboard brake shoes are common. The out-
board brake shoes are marked with an (LH) or (RH)
to denote which side of the vehicle to be installed on
(Fig. 6).
(3) Remove protective paper from the noise sup-
pression gasket and position the properly marked
outboard brake shoe assembly onto the caliper (Fig.
7). (4) Install new inboard brake shoe assembly in cal-
Fig. 3 Storing Caliper
Fig. 4 Prying Outboard Shoe Assembly Away from Caliper
Fig. 5 Removing or Installing Inboard ShoeAssembly
Fig. 6 Brake Shoe Identification
Ä BRAKES 5 - 39

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

(5) Clamp caliper in vise (with protective caps on
vise jaws). (6) Remove dust boot from the brake caliper and
discard (Fig. 1).
(7) Using a plastic trim stick, work piston seal out of
its groove in caliper piston bore (Fig. 2). Discard old
seal. Do not use a screwdriver or other metal tool
for this operation, because of the possibility of
scratching piston bore or burring edges of seal
groove. The double pin caliper uses a sealed for life bushing
and sleeve assembly. If required this assembly can be
serviced using the following procedure. (1) Push out and then pull the inner sleeve from
inside of the bushing using your fingers as shown in
(Fig. 3)
(2) Using your fingers collapse one side of the bush-
ing. Then pull on the opposite side to remove the
bushing from the brake caliper assembly (Fig. 4).
CLEANING AND INSPECTION OF BRAKE CALIPER
Clean all parts using alcohol or a suitable solvent
and wipe dry using only a lint free cloth, no lint
residue can remain in caliper bore. Clean out all drilled
passages and bores. (Whenever a caliper has been
disassembled, a new boot and seal must be in-
stalled at assembly). Inspect the piston bore for scoring or pitting. Bores
that show light scratches or corrosion, can usually be
cleared of the light scratches or corrosion using crocus
cloth. Bores that have deep scratches or scoring should be
honed. Use Caliper Hone, Special Tool C-4095, or
equivalent providing the diameter of the bore is not
increased more than 0.0254 mm (0.001 inch) (Fig. 5). If the bore does not clean up within this specification,
a new caliper housing should be installed. Install a new
piston if the old one is pitted or scored. When using Caliper Honing Tool, Special Tool
C-4095, coat the stones and bore with brake fluid.
After honing the bore, carefully clean the seal
and boot grooves with a stiff non-metallic rotary
brush.
Fig. 1 Removing Piston Dust Boot
Fig. 2 Removing Piston Seal
Fig. 3 Removing Inner Sleeve
Ä BRAKES 5 - 41

Use extreme care in cleaning the caliper after
honing. Remove all dirt and grit by flushing the
caliper with brake fluid; wipe dry with a clean,
lint free cloth and then clean a second time.
ASSEMBLING DISC BRAKE CALIPER
Clamp caliper in vise (with protective caps on vise
jaws).
CAUTION: Excessive vise pressure will cause bore
distortion and binding of piston. Dip new piston seal in clean brake fluid and install
in the groove of the caliper bore. Seal should be po-
sitioned at one area in groove and gently worked
around the groove (Fig. 1), using only your fingers
until properly seated. NEVER USE AN OLD PISTON SEAL. (Be sure
that fingers are clean and seal is not twisted or
rolled) (Fig. 1).
Coat new piston boot with clean brake fluid leav-
ing a generous amount inside boot. Position dust boot over piston after coating with
brake fluid. Install piston into caliper bore pushing it past the
piston seal until it bottoms in the caliper bore (Fig.
2).
CAUTION: Force must be applied to the piston uni-
formly to avoid cocking and binding of the piston in
the bore of the caliper.
Fig. 1 Installing New Piston Seal
Fig. 2 Pushing Piston into Bore
Fig. 4 Removing Bushings From Caliper
Fig. 5 Honing Piston Bore
5 - 42 BRAKES Ä