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Home >> Lexus >> 2006 >> LS 430 V8-4.3L (3UZ-FE) >> Repair and Diagnosis >> Brakes and Traction Control >> Hydraulic System >> Brake Master Cylinder >> Service and Repair

Brake Master Cylinder: Service and Repair






BRAKE MASTER CYLINDER SUB-ASSEMBLY
OVERHAUL
1. REMOVE ENGINE ROOM SIDE COVER
2. SEPARATE ENGINE ROOM NO.3 R/B
a. Remove the bolt and separate the engine room No.3 R/B.
3. DRAIN BRAKE FLUID
a. Draw out fluid with syringe.

NOTICE: Wash brake fluid off immediately if it adheres to any painted surfaces.

4. REMOVE BRAKE MASTER CYLINDER SUB-ASSEMBLY





a. Remove the clamp from the 2 brake tubes.





b. Using SST, remove the 2 brake tubes from the master cylinder and ABS & TRACTION actuator assembly.
SST 09751-36011





c. Disconnect the brake fluid level warning switch connector from the brake master cylinder reservoir.
d. Remove the 2 nuts, vacuum check valve bracket and brake master cylinder sub-assembly.





5. REMOVE BRAKE MASTER CYLINDER RESERVOIR SUB-ASSEMBLY
a. Remove the brake master cylinder reservoir filler cap and master cylinder reservoir strainer.

HINT: Using 2 fingers, pull up and turn the master cylinder reservoir strainer counterclockwise to remove.

b. Remove the set screw and pull out the reservoir.
6. REMOVE MASTER CYLINDER RESERVOIR GROMMET





7. REMOVE BRAKE MASTER CYLINDER STRAIGHT PIN
a. Push in the piston by hand and remove the master cylinder straight pin by turning over the cylinder body.

HINT: Place a shop rag to avoid the master cylinder straight pin from getting damaged.

8. REMOVE BRAKE MASTER CYLINDER KIT





a. Place the brake master cylinder sub-assembly in a vise.

NOTICE: Do not damage the brake master cylinder sub-assembly by over tightening the vise.

b. Push in the No. 1 piston by hand, and remove the snap ring with snap ring pliers.
c. Remove the No. 1 piston by hand, pulling straight out, not at an angle.

NOTICE:
^ If they are pulled out and installed at an angle, there is a possibility that the cylinder bore could be dam aged.
^ At the time of reassembly, be careful not to damage the rubber lips on the pistons.





d. Place a shop rag and 2 wooden blocks on the work table, and lightly tap the cylinder flange against the block edges until the No.2 piston drops out of the cylinder.

NOTICE: Be careful not to scratch the master cylinder bore.

HINT: Make sure that the distance (A) from the shop rag to the top of the blocks is at least 100 mm (3.94 inch).

e. Remove the O-ring from the master cylinder body.
9. INSTALL BRAKE MASTER CYLINDER KIT
a. Place the brake master cylinder sub-assembly in a vise.
b. Apply lithium soap base glycol grease to new No. 1 piston sub-assembly and No.2 piston sub-assembly.





c. Using a flat tip driver, insert the No.2 piston sub-assembly horizontally and insert the master cylinder straight.

NOTICE: Make sure that the No.2 piston sub-assembly and master cylinder straight pin are installed properly.

d. Install the No.1 piston sub-assembly straight.

NOTICE:
^ If the piston is inserted at an angle, there is a possibility that the cylinder bore could be damaged.
^ Be careful not to damage the rubber lips on the pistons.





e. Push in the piston by hand and install the snap ring using snap ring pliers.
f. Apply lithium soap base glycol grease to a new O-ring and install the O-ring to the master cylinder.
10. INSTALL MASTER CYLINDER RESERVOIR GROMMET
a. Apply lithium soap base glycol grease to the 2 master cylinder reservoir grommets.
b. Install the 2 master cylinder reservoir grommets to the master cylinder reservoir sub-assembly.
11. INSTALL BRAKE MASTER CYLINDER RESERVOIR SUB-ASSEMBLY
a. Install the master cylinder reservoir sub-assembly to the master cylinder sub-assembly with the set screw.
b. Install the master cylinder reservoir strainer and master cylinder reservoir filler cap.
c. Connect the brake fluid warning switch connector.
12. INSPECT AND ADJUST BRAKE BOOSTER PUSH ROD





a. Depress the brake pedal several times while the engine is stopped to release the pressure.
b. Set SST on the brake master cylinder sub-assembly and lower the pin of the SST until it slightly touches the piston.
c. Apply chalk to the flat surfaced tip of the SST pin.
SST 09737-00013





d. Turn SST upside down and place it on brake booster assembly. Measure the clearance between the brake booster assembly and SST
Clearance: 0 mm (0 inch)





HINT:
^ If there is a clearance between the SST main body and the shell of the brake booster assembly (floating SST main body), the push rod is protruding too far.
^ If the chalk does not stick on the brake booster push rod, the push rod protrusion is insufficient.
^ Adjust the clearance if either of the above conditions is detected.





e. Using SST, adjust the booster push rod length until the push rod lightly touches the pin head.
SST 09737-00020
13. INSTALL BRAKE MASTER CYLINDER SUB-ASSEMBLY





a. Install the brake master cylinder sub-assembly and vacuum check valve bracket with 2 nuts.
Torque: 13 Nm (130 kgf-cm, 9 ft. lbs.)
b. Connect the brake fluid level warning switch connector to the master cylinder reservoir.





c. Using SST, install the brake tube to the brake master cylinder sub-assembly and ABS & TRACTION actuator assembly.
SST 09751-36011
Torque: 15 Nm (155 kgf-cm, 11 ft. lbs.)
d. Install the clamp.
14. FILL RESERVOIR WITH BRAKE FLUID
15. BLEED MASTER CYLINDER
16. BLEED BRAKE LINE
17. CHECK FLUID LEVEL IN RESERVOIR
18. CHECK FOR BRAKE FLUID LEAKAGE
If fluid leaks, tighten or replace the leaking part.
19. INSTALL ENGINE ROOM NO.3 R/B
a. Install the engine room No.3 R/B with a bolt.
20. INSTALL ENGINE ROOM SIDE COVER


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