brakes DAEWOO LACETTI 2004 Service Service Manual

4B – 8IMASTER CYLINDER
DAEWOO V–121 BL4
6. Press the pistons into the cylinder bore using a
wooden or a plastic drift.
Notice : When installing the new retaining ring, take care
not to damage the cylinder bore.
7. Insert the new retaining ring into the groove in the
cylinder bore (the non–ABS cylinder body is
shown). Remove the welding rod.
8. Move the pistons backward and forward after instal-
lation to check for free movement.
9. Lubricate the seal ring and insert the seal into the
cylinder bore. The open side must face outward
until the seal rests on the piston.
10. Install the brake fluid reservoir to the master cylin-
der. Refer to ”Brake Fluid Reservoir” in this section.
11. Install the master cylinder assembly. Refer to Mas-
ter Cylinder Assembly in this section
12. Raise and suitably support the vehicle.
13. Bleed the braking system. Refer to Section 4A, Hy-
draulic Brakes orSection 4F, Antilock Brake Sys-
tem.
14. Lower the vehicle.

MASTER CYLINDER 4B – 9
DAEWOO V–121 BL4
GENERAL DESCRIPTION
AND SYSTEM OPERATION
MASTER CYLINDER
The master cylinder is designed for use in a diagonal–split
system. One front and one diagonally opposite rear brake
are served by the primary piston. The opposite front and
rear brakes are served by the secondary piston. The mas-
ter cylinder incorporates the functions of the standard dual
master cylinder, plus a low fluid level indicator and the pro-
portioning valves in the non–antilock braking system. The
proportioning valves limit the outlet pressure to the rear
brakes after a predetermined master cylinder pressure
has been reached.
Important :
S Replace all the components included in the repair
kits used to service this master cylinder.S Lubricate rubber parts with clean brake fluid to ease
assembly.
S Do not use lubricated shop air on brake parts, as
this may damage rubber components.
S If any hydraulic component is removed or discon-
nected, it may be necessary to bleed all or part of
the brake system.
S The torque values specified are for dry, unlubri-
cated fasteners.
S Perform all service operations on a clean bench,
free from all traces of mineral oil.
FLUID LEVEL SENSOR
The master cylinder is equipped with a fluid level sensor.
This sensor will activate the BRAKE light if a low fluid level
condition is detected. Once the fluid level is corrected, the
BRAKE light will go out.

POWER BOOSTER 4C – 3
DAEWOO V–121 BL4
2. Remove the shaft and the rubber O–ring.
3. Remove the clip on the vacuum hose connection on
the booster.
4. Disconnect the brake stoplamp switch.
5. Remove the brake pedal spring.
6. Disconnect the clip and the pushrod pin from the
pedal bracket assembly. Refer to Section 4A, Hy-
draulic Brakes.
7. Remove the booster mounting nuts from the studs
protruding from the dash panel and remove the
booster.
8. Remove the rubber boot.
9. Holding the hex nut, twist off the pushrod clevis.
10. Remove the hex nut from the pushrod.

POWER BOOSTER 4C – 5
DAEWOO V–121 BL4
8. Install the new vacuum hose to the booster. Refer
to ”Vacuum Hose” in this section.
9. Install the hose clamps on the vacuum hose, and
snap the vacuum hose in the revolving clip.
10. Install the pushrod pin to the brake pedal bracket
assembly and connect the clip and the spring. Re-
fer to Section 4A, Hydraulic Brakes.
11. Install the brake stoplamp switch. Refer to Section
4A, Hydraulic Brakes.

4C – 6IPOWER BOOSTER
DAEWOO V–121 BL4
GENERAL DESCRIPTION
AND SYSTEM OPERATION
POWER BOOSTER
This booster is a single or tandem diaphragm, vacuum–
suspended unit. In a normal operating mode, with the ser-
vice brakes in the release position, a vacuum–suspended
booster operates with a vacuum on both sides of its dia-phragm. When the brakes are applied, air at atmospheric
pressure is admitted to one side of the diaphragm to pro–
vide the power assist. When the brakes are released, at-
mospheric air is shut off from that side of the dia–phragm.
The air is then drawn from the booster through the vacuum
check valve by the vacuum source.
Important : If any hydraulic component is removed or dis-
connected, it may be necessary to bleed all or part of the
brake system.

SECTION : 4D
FRONT DISC BRAKES
TABLE OF CONTENTS
SPECIFICATIONS4D–1 . . . . . . . . . . . . . . . . . . . . . . . . . .
Fastener Tightening Specirications 4D–1. . . . . . . . . .
DIAGNOSIS4D–1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lining Inspection 4D–1. . . . . . . . . . . . . . . . . . . . . . . . . .
Rotor Inspection 4D–1. . . . . . . . . . . . . . . . . . . . . . . . . .
MAINTENANCE AND REPAIR4D–3 . . . . . . . . . . . . . . .
ON–VEHICLE SERVICE 4D–3. . . . . . . . . . . . . . . . . . . . .
Shoe and Lining 4D–3. . . . . . . . . . . . . . . . . . . . . . . . . . Caliper Assembly 4D–3. . . . . . . . . . . . . . . . . . . . . . . . . .
Rotor 4D–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Splash Shield 4D–5. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
UNIT REPAIR 4D–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Caliper Overhaul 4D–6. . . . . . . . . . . . . . . . . . . . . . . . . .
GENERAL DESCRIPTION AND SYSTEM
OPERATION4D–9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Disc Brake Caliper Assembly 4D–9. . . . . . . . . . . . . . . .
SPECIFICATIONS
FASTENER TIGHTENING SPECIRICATIONS
ApplicationNSmLb–FtLb–In
Brake Hose Inlet Fitting–to–Caliper Bolt4030–
Caliper Bleeder Valve8–71
Caliper–to–Steering Knuckle Mounting Bolts9570–
Retaining Frame–to–Caliper Housing Bolts2720–
Rotor–to–Front Wheel Hub Detent Screw4–35
Splash Shield–to–Steering Knuckle Screws4–35
DIAGNOSIS
LINING INSPECTION
1. Raise and suitably support the vehicle.
2. Remove the front wheels. Refer to Section 2E,
Tires and Wheels.
3. Visually check the linings for minimum thickness
and wear.
4. Measure the thickness.
Important : The minimum thickness of the inner or the
outer pad is 7 mm (0.28 inch).
5. Install the brake pads in axle sets only.
6. Install the front wheels. Refer to Section 2E, Tires
and Wheels.
7. Lower the vehicle.ROTOR INSPECTION
Thickness variation can be checked by measuring the
thickness of the rotor at four or more points around the cir-
cumference of the rotor. All measurements must be made
at the same distance in from the edge of the rotor.
A rotor that varies by more than 0.01 mm (0.0004 inch) can
cause pedal pulsations and/or front end vibration during
brake applications. A rotor that does not meet these speci-
fications should be refinished to specifications or re-
placed.

4D – 2IFRONT DISC BRAKES
DAEWOO V–121 BL4
During manufacturing, the brake rotor and the tolerances
of the braking surface regarding flatness, thickness varia-
tion, and lateral runout are held very close. The mainte-
nance of close tolerances on the shape of the braking sur-
faces is necessary to prevent brake roughness.
In addition to these tolerances, the surface finish must be
held to a specified range. The control of the braking sur-
face finish is necessary to avoid pulls and erratic perfor-
mance and to extend lining life.
Using a commercially available dial indicator, check lateral
runout as follows:
Notice : Permissible lateral runout is a maximum 0.03 mm
(0.0012 inch). If lateral runout exceeds the specification,
ensure that there is no dirt between the rotor and the hub
and that contact surfaces are smooth and free from burrs.
1. Position the shift lever in NEUTRAL.2. Remove the rotor. Refer to ”Rotor” in this section.
3. Fasten the brake rotor to the wheel hub with two
wheel bolts.
4. Fasten a dial indicator to the brake caliper.
5. Set the gauge probe tip to approximately 10 mm
(0.39 inch) from the outer edge of the brake rotor,
perpendicular to the disc and under slight preload.
6. Remove the dial indicator and the wheel bolts con-
necting the rotor to the hub.
Important : Since accurate control of the rotor tolerances
is necessary for proper performance of the disc brakes, re-
finishing of the rotor should be done only with precision
equipment.
7. Refinish the rotor, if required, with precision equip-
ment. Discard the rotor if it fails to meet the above
specifications after refinishing.
8. Install the rotor. Refer to ”Rotor” in this section.

FRONT DISC BRAKES 4D – 3
DAEWOO V–121 BL4
MAINTENANCE AND REPAIR
ON–VEHICLE SERVICE
SHOE AND LINING
Removal Procedure
1. Raise and suitably support the vehicle.
2. Remove the front wheels. Refer to Section 2E,
Tires and Wheels.
3. Remove the lower bolt of the caliper assembly re-
taining frame.
Important : Caliper assembly removal is not necessary to
service the brake pads.
4. Pull the caliper piston housing up.
5. Remove the brake pads.
Installation Procedure
1. Measure the minimum lining thickness. Refer to
”Lining Inspection” in this section.
2. Install the brake pads into the caliper.
3. Push the piston inward, if needed.
Notice : Take care not to damage the piston seal when the
piston housing frame is pulled down.
4. Pull down the caliper piston housing and secure it
to the retaining frame with the lower bolt.
Tighten
Tighten the retaining frame–to–caliper housing bolts
to 27 NSm (20 lb–ft).
5. Install the front wheels. Refer to Section 2E, Tires
and Wheels.
6. Lower the vehicle.
CALIPER ASSEMBLY
Removal Procedure
1. Raise and suitably support the vehicle.
2. Mark the position of the front wheels relative to the
wheel hubs and remove the wheels. Refer to Sec-
tion 2E, Tires and Wheels.
3. Remove the bolt and the washers attaching the
brake hose to the caliper.
4. Disconnect the brake hose, and plug the openings
in the caliper and the brake hose to prevent fluid
loss and contamination.
5. Remove the caliper mounting bolts from the steer-
ing knuckle, and remove the caliper assembly.

4D – 4IFRONT DISC BRAKES
DAEWOO V–121 BL4
Installation Procedure
1. Install the caliper assembly with the mounting bolts.
Tighten
Tighten the caliper–to–steering knuckle mounting
bolts to 95 NSm(70 lb–ft).
2. Connect the brake hose.
Tighten
Tighten the brake hose inlet fitting–to–caliper bolt and
washers to 40 NSm (30 lb–ft).
3. Install the front wheels. Refer to Section 2E, Tires
and Wheels.
4. Lower the vehicle.
5. Fill the master cylinder to the proper level with
clean brake fluid.
6. Bleed the caliper. Refer to Section 4A, Hydraulic
Brakes.
7. Recheck the fluid level.
Notice : Do not move the vehicle until a firm pedal is ob-
tained, or improper braking action will result.
8. Repeatedly press the brake pedal to bring the pads
in contact with the rotor.
ROTOR
Removal Procedure
Notice : Do not hang the caliper assembly from the brake
hose. Any resulting internal hose restriction will impede
uniform braking action.
Important : To guarantee uniform braking on both sides,
both rotors must have identical surfaces regarding
smoothness and scoring depth. For this reason, always
replace both rotors.
1. Remove the caliper assembly without disconnecting
the brake hoses. Refer to ”Caliper Assembly” in this
section.
2. Remove the rotor–to–front wheel hub detent
screws.
3. Pull off the rotor.
Installation Procedure
1. Inspect the rotor. Refer to ”Rotor Inspection”in this
section.
2. Install the rotor to the front wheel hub by tightening
the detent screw.
Tighten
Tighten the rotor–to–front wheel hub detent screw to
4 NSm (35 lb–in).
3. Install the caliper assembly. Refer to ”Caliper As-
sembly” in this section.

FRONT DISC BRAKES 4D – 5
DAEWOO V–121 BL4
SPLASH SHIELD
Removal Procedure
1. Remove the rotor. Refer to ”Rotor” in this section.
2. Remove the screws for the splash shield from the
steering knuckle.
3. Remove the splash shield.
Installation Procedure
1. Install the splash shield.
2. Secure the splash shield to the steering knuckle
with the screws.
Tighten
Tighten the splash shield–to–steering knuckle screws
to 4 NSm (35 lb–in).
3. Install the rotor. Refer to ”Rotor” in this section.