brake pads LEXUS SC400 1991 Service Repair Manual

GENERAL DESCRIPTION
BR03E±06
1. Care must be taken to replace each part properly as it could affect the \
performance of the brakesystem and result in a driving hazard. Replace the parts with parts of the same part number or
equivalent.
2. It is very important to keep parts and the area clean when repairing the\
brake system.
3. If the vehicle is equipped with a mobile communication system, refer to the precaution \
in the IN section.
DESCRIPTION
BR03F±03
The service brakes consist of a foot brake which changes rotational energy to therma\
l energy to stop the
vehicle while it is being driven and a parking brake to keep the vehicle from m\
oving while it is parked.
OPERATION
FOOT BRAKE
BR03G±06
When the brake pedal is depressed, a vacuum builds up in the booster whi\
ch amplifies the pedal force,
pressing on the piston in the master cylinder. The piston movement raises the hydraulic pressure in the
cylinder. This hydraulic pressure is then applied to each respective brake cylin\
der, and acts to press the
brake pads against the rotating discs. The resulting friction converts the ro\
tational energy to thermal ener-
gy, stopping the vehicle.
BR±2±
BRAKE SYSTEM OPERATION
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GENERAL DESCRIPTION
BR03E±06
1. Care must be taken to replace each part properly as it could affect the \
performance of the brakesystem and result in a driving hazard. Replace the parts with parts of the same part number or
equivalent.
2. It is very important to keep parts and the area clean when repairing the\
brake system.
3. If the vehicle is equipped with a mobile communication system, refer to the precaution \
in the IN section.
DESCRIPTION
BR03F±03
The service brakes consist of a foot brake which changes rotational energy to therma\
l energy to stop the
vehicle while it is being driven and a parking brake to keep the vehicle from m\
oving while it is parked.
OPERATION
FOOT BRAKE
BR03G±06
When the brake pedal is depressed, a vacuum builds up in the booster whi\
ch amplifies the pedal force,
pressing on the piston in the master cylinder. The piston movement raises the hydraulic pressure in the
cylinder. This hydraulic pressure is then applied to each respective brake cylin\
der, and acts to press the
brake pads against the rotating discs. The resulting friction converts the ro\
tational energy to thermal ener-
gy, stopping the vehicle.
BR±2±
BRAKE SYSTEM OPERATION
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FRONT BRAKE (SC400)
COMPONENTS
BR040±0A
BRAKE PADS REPLACEMENT
BR0PU±01
1. REMOVE FRONT WHEELRemove the wheel and temporarily fasten the disc with the
hub nuts.
2. INSPECT PAD LINING THICKNESS Check the pad thickness through the caliper inspection hole
and replace the pads if it is not within the specification.
Minimum thickness:
1.0 mm (0.039 in.)
±
BRAKE SYSTEM FRONT BRAKE (SC400)BR±29
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3. LIFT UP CALIPER
(a) Hold the sliding pin on the bottom and loosen the installationbolt.
(b) Remove the installation bolt.
(c) Lift up and suspend the caliper.
HINT: Do not disconnect the flexible hose from the caliper.
4. REMOVE FOLLOWING PARTS:
(a) 2 anti±squeal springs
(b) 2 brake pads
(c) 4 anti±squeal shims
(d) 4 pad support plates
5. CHECK DISC THICKNESS AND RUNOUT (See page BR±33 )
6. INSTALL UNDER SIDE PAD SUPPORT PLATES
7. INSTALL UPPER SIDE PAD SUPPORT PLATES
(a) Using cleaner, wipe off dust, water, oil, etc. from the pad support plate contact area of the torque plate.
(b) Remove the pad support cover sheets from new pad support plate.
BR±30
±
BRAKE SYSTEM FRONT BRAKE (SC400)
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(c) Install the new pad support plates.
8. INSTALL NEW PADS
(a) Apply disc brake grease to both sides of the inner anti±squeal
shim.
(b) Install the 2 anti±squeal shims on each pad.
(c) Install inner pad with the pad wear indicator plates facing downward.
(d) Install the outer pad.
NOTICE: There should be no oil or grease adhering to the fric-
tion surfaces of the pads or the disc.
(e) Install the 2 anti±squeal springs.
9. INSTALL CALIPER
(a) Draw out a small amount of brake fluid from the reservoir.
(b) P re ss in th e pisto n with wa te r pu mp plie rs or simila r
implement.
HINT: If the piston is difficult to push in, loosen the bleeder
plug and push in the piston while letting some brake fluid es-
cape.
(c) Install the caliper.
(d) Hold the sliding pin and torque the installation bolt.
Torque: 34 N Vm (350 kgf Vcm, 25 ft Vlbf)
10. INSTALL FRONT WHEEL
11. CHECK THAT FLUID LEVEL IS AT MAX LINE
CALIPER REMOVAL
BR042±0C
1. DISCONNECT FLEXIBLE HOSE
(a) Remove the union bolt and 2 gaskets from the caliper, then
disconnect the flexible hose from the caliper.
(b) Use a container to catch the brake fluid as it drains out.
±
BRAKE SYSTEM FRONT BRAKE (SC400)BR±31
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2. REMOVE CALIPER
(a) Hold the sliding pin and loosen the 2 installation bolts.
(b) Remove the 2 installation bolts.
(c) Remove the caliper from the torque plate.
3. REMOVE FOLLOWING PARTS:
(a) 2 anti±squeal springs
(b) 2 brake pads
CALIPER DISASSEMBLY
BR043±0B
1. REMOVE CYLINDER BOOT SET RINGS AND CYLINDERBOOT
Using a screwdriver, remove the 2 cylinder boot set rings and
cylinder boots from the caliper.
2. REMOVE PISTONS
(a) Place a piece of cloth or similar article between the piston and
the caliper.
(b) Use compressed air to remove the pistons from the caliper.
CAUTION: Do not place your fingers in front of the piston when
using compressed air.
3. REMOVE PISTON SEALS Using a screwdriver, remove the piston seal from the caliper.
BR±32
±
BRAKE SYSTEM FRONT BRAKE (SC400)
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2. INSTALL DUST BOOTS AND SLIDING PINS
(a) Using a 19 mm socket and hammer, tap in 2 new dust bootsinto the torque plate.
(b) Confirm that the metal plate portion of the dust boot fits
snugly in the torque plate.
(c) Insert 2 sliding pins into the torque plate.
NOTICE: Insert the sliding pin with sliding bushing A into the
upper part, and insert the sliding pin with sliding bushing B
into the lower part.
3. INSTALL PISTON SEALS AND PISTONS IN CALIPER
4. INSTALL CYLINDER BOOTS AND CYLINDER BOOT SET RINGS
CALIPER INSTALLATION
BR046±0C
1. INSTALL FOLLOWING PARTS:
(a) 2 brake pads
(b) 2 anti±squeal springs
±
BRAKE SYSTEM FRONT BRAKE (SC400)BR±35
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REAR BRAKE
(Disc Brake)
COMPONENTS
BR047±06
REPLACEMENT OF BRAKE PADS
BR0PV±01
1. REMOVE REAR WHEELRemove the wheel and temporarily fasten the disc with the
hub nuts.
2. INSPECT PAD LINING THICKNESS Check the pad thickness through the caliper inspection hole
and replace pads if the thickness is not within the specifica-
tion.
Minimum thickness:
1.0 mm (0.039 in.)
±
BRAKE SYSTEM REAR BRAKE (Disc Brake)BR±37
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3. LIFT UP CALIPER
(a) Hold the sliding pin on the bottom and loosen the installationbolt.
(b) Remove the installation bolt.
(c) Lift up and suspend the caliper.
HINT: Do not disconnect the flexible hose from the caliper.
4. REMOVE FOLLOWING PARTS:
(a) 2 anti±squeal springs
(b) 2 brake pads
(c) 4 anti±squeal shims
(d) 4 pad support plates
5. CHECK DISC THICKNESS (See page BR±41)
6. CHECK DISC RUNOUT (See page BR±41)
7. INSTALL PAD SUPPORT PLATES
BR±38
±
BRAKE SYSTEM REAR BRAKE (Disc Brake)
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8. INSTALL NEW PADS
(a) Apply disc brake grease to both sides of the inner anti±squeal
shim.
(b) Install the 2 anti±squeal shims on each pad.
(c) Install the inner pad with the pad wear indicator plates facing
downward.
(d) Install the outer pad.
NOTICE: There should be no oil or grease adhering to the fric-
tion surfaces of the pads or the disc.
(e) Install the 2 anti±squeal springs.
9. INSTALL CALIPER
(a) Draw out a small amount of brake fluid from the reservoir.
(b) P re ss in th e pisto n with wa te r pu mp plie rs or simila r implement.
HINT: If the piston is difficult to push in, loosen the bleeder
plug and push in the piston while letting some brake fluid es-
cape.
(c) Install the caliper.
(d) Hold the sliding pin and torque the installation bolt.
Torque: 34 N Vm (350 kgf Vcm, 25 ft Vlbf)
10. INSTALL REAR WHEEL
11. CHECK THAT FLUID LEVEL IS AT MAX LINE
CALIPER REMOVAL
BR0EN±04
1. DISCONNECT FLEXIBLE HOSE
(a) Remove the union bolt and 2 gaskets from the caliper, then
disconnect the flexible hose from the caliper.
(b) Use a container to catch the brake fluid as it drains out.
2. REMOVE CALIPER
(a) Hold the sliding pin and loosen the 2 installation bolts.
(b) Remove the 2 installation bolts.
(c) Remove the caliper from the torque plate.
±
BRAKE SYSTEM REAR BRAKE (Disc Brake)BR±39
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