Text preview for : en_4j2_4c.pdf part of Daewoo Nubira/Lacetti Also known as: Chevrolet Nubira / Lacetti, Chevrolet Optra Optra5, Suzuki Forenza Reno Covers the 1.4L, 1.6L and 1.8L engine. Year 2004



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SECTION : 4C

POWER BOOSTER
TABLE OF CONTENTS
SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . 4C­1 Fasrener Tightening Specifications . . . . . . . . . . 4C­1 DIAGNOSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4C­1 Power Booster Functional Check . . . . . . . . . . . . 4C­1 MAINTENANCE AND REPAIR . . . . . . . . . . . . . . . 4C­2 ON­VEHICLE SERVICE . . . . . . . . . . . . . . . . . . . . . 4C­2 Vacuum Hose . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4C­2 Power Booster Assembly . . . . . . . . . . . . . . . . . . . 4C­2 GENERAL DESCRIPTION AND SYSTEM OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4C­6 Power Booster . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4C­6

SPECIFICATIONS
FASRENER TIGHTENING SPECIFICATIONS
Application Booster­to­Bracket Nuts (Right­Hand Drive) Booster­to­Dash Drive) Brake Line Fittings Panel Nut (Left­Hand NSm 22 22 18 16 Lb­Ft 16 16 13 12 Lb­In ­ ­ ­ ­

Booster Hex Nut and Pushrod Clevis

DIAGNOSIS
POWER BOOSTER FUNCTIONAL CHECK
1. 2. 3. With the engine stopped, eliminate vacuum in the booster by pumping the brake pedal several times. Push the pedal down and hold in this position. Start the engine. 4. The booster is OK if the pedal drops further because of extra force produced. If the brake pedal does not drop, the vacuum system (vacuum hoses, check valve, etc.) is probably defective and should be checked. If no defect is revealed by checking the vacuum system, the defect is in the booster itself.

4C ­ 2IPOWER BOOSTER

MAINTENANCE AND REPAIR
ON­VEHICLE SERVICE VACUUM HOSE
Removal Procedure
1. Spread the clip on the vacuum hose connection at the intake manifold and move the clip slightly toward the brake booster. Pull the hose from the union nut connection. If the hose does not remove easily or is deteriorated, pry off and discard the hose. Spread the clip on the vacuum hose connection to the brake booster, and move the clip clear of the booster. Remove the vacuum hose.

2.

3.

4.

Installation Procedure
1. 2. Mount the vacuum hose and ensure the connections are tight on each end. Check the function of the booster. Refer to the "Power Booster Functional Check" in this section.

POWER BOOSTER ASSEMBLY
Removal Procedure
1. Remove the master cylinder. Refer to Section 4B, Master Cylinder Assembly.

DAEWOO V­121 BL4

POWER BOOSTER 4C ­ 3
2. Remove the shaft and the rubber O­ring.

3. 4. 5. 6.

Remove the clip on the vacuum hose connection on the booster. Disconnect the brake stoplamp switch. Remove the brake pedal spring. Disconnect the clip and the pushrod pin from the pedal bracket assembly. Refer to Section 4A, Hydraulic Brakes.

7.

8.

Remove the booster mounting nuts from the studs protruding from the dash panel and remove the booster. Remove the rubber boot.

9. Holding the hex nut, twist off the pushrod clevis. 10. Remove the hex nut from the pushrod.

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4C ­ 4IPOWER BOOSTER Installation Procedure
1. 2. Check the pushrod and the pushrod clevis for damage and proper fit. Install the hex nut and the pushrod clevis on the booster shaft.

Tighten
Tighten the booster hex nut and the pushrod clevis to 18 NSm (13 lb­ft).

3.

Measure the distance from the booster to the center of the fork pin bore. Important : This measurement should be 120 mm (4.7 inches). Important : Install the rubber boot on the booster.

4.

Install the booster and the mounting nuts to the dash panel.

Tighten
Tighten the booster­to­dash panel nuts to 22 NSm (16 lb­ft).

5. 6. 7.

Attach the shaft and the rubber O­ring. Connect the master cylinder to the booster. Refer to Section 4B, Master Cylinder Assembly. Connect the brake line fittings to the hydraulic modulator, if applicable.

Tighten
Tighten the brake line fittings to 16 NSm (12 lb­ft).

Tighten
Tighten the master cylinder attaching nuts to 24 NSm (18 lb­ft).

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POWER BOOSTER 4C ­ 5
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. Refer to Section 4A, Hydraulic Brakes. 11. Install the brake stoplamp switch. Refer to Section 4A, Hydraulic Brakes.

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4C ­ 6IPOWER BOOSTER

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 service brakes in the release position, a vacuum­suspended 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, atmospheric air is shut off from that side of the dia­phragm. 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 disconnected, it may be necessary to bleed all or part of the brake system.

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