To the top of the document
Nubira-Lacetti
To Previous Page To Next Page
GMDE Start Page Load static TOC Load dynamic TOC Help?

SECTION 4C

POWER BOOSTER

SPECIFICATIONS

Fasrener Tightening Specifications

Application
N•m
Lb-Ft
Lb-In
Booster-to-Bracket Nuts (Right-Hand Drive)
22
16
-
Booster-to-Dash Panel Nut (Left-Hand Drive)
22
16
-
Booster Hex Nut and Pushrod Clevis
18
13
-
Brake Line Fittings
16
12
-

DIAGNOSIS

Power Booster Functional Check

  1. With the engine stopped, eliminate vacuum in the booster by pumping the brake pedal several times.
  2. Push the pedal down and hold in this position.
  3. 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.

MAINTENANCE AND REPAIR

ON-VEHICLE SERVICE


J3B14C01
Display graphicTranslations of text in graphics


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.
  2. Pull the hose from the union nut connection. If the hose does not remove easily or is deteriorated, pry off and discard the hose.
  3. Spread the clip on the vacuum hose connection to the brake booster, and move the clip clear of the booster.
  4. Remove the vacuum hose.

J3B14C01
Display graphicTranslations of text in graphics


Installation Procedure

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

J3B14B01
Display graphicTranslations of text in graphics


Power Booster Assembly

Removal Procedure

  1. Remove the master cylinder. Refer to Section 4B, Master Cylinder Assembly.

    2. J3B14C02
    Display graphicTranslations of text in graphics


  2. Remove the shaft and the rubber O-ring.

    3. J3B14C01
    Display graphicTranslations of text in graphics


  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, Hydraulic Brakes.

    7. J3B14C03
    Display graphicTranslations of text in graphics


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

    9. J3B14C04
    Display graphicTranslations of text in graphics


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

J3B14C05
Display graphicTranslations of text in graphics


Installation Procedure

  1. Check the pushrod and the pushrod clevis for damage and proper fit.
  2. Install the hex nut and the pushrod clevis on the booster shaft.

    3. Tighten
    Tighten the booster hex nut and the pushrod clevis to 18 N•m (13 lb-ft).


    J3B14C06
    Display graphicTranslations of text in graphics


  3. Measure the distance from the booster to the center of the fork pin bore.

    4. Important : This measurement should be 120 mm (4.7 inches).

    Important : Install the rubber boot on the booster.


    J3B14C07
    Display graphicTranslations of text in graphics


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

    5. Tighten
    Tighten the booster-to-dash panel nuts to 22 N•m (16 lb-ft).


    J3B14C02
    Display graphicTranslations of text in graphics


  5. Attach the shaft and the rubber O-ring.
  6. Connect the master cylinder to the booster. Refer to Section 4B, Master Cylinder Assembly.
  7. Connect the brake line fittings to the hydraulic modulator, if applicable.

    8. Tighten
    Tighten the brake line fittings to 16 N•m (12 lb-ft).

    Tighten
    Tighten the master cylinder attaching nuts to 24 N•m (18 lb-ft).


    J3B14C01
    Display graphicTranslations of text in graphics


  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.

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 vacuum-suspended booster operates with a vacuum on both sides of its diaphragm. 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 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 disconnected, it may be necessary to bleed all or part of the brake system.



To Previous Page To Next Page
© Copyright General Motors Chevrolet Europe. All rights reserved