Vacuum Brake Booster: Adjustments

NOTE:
- The master cylinder pushrod-to-piston clearance must be checked and adjustments made, if necessary, before installing the master cylinder.
- ABS type is shown, conventional brake type is similar.





1. Set the special tool on the master cylinder body; push in the center shaft until the top of it contacts the end of the secondary piston by turning the adjusting nut.

2. Without disturbing the center shaft's position, install the special tool upside down on the booster.
3. Install the master cylinder nuts, and tighten to the specified torque.
4. Connect the booster in-line with a vacuum gauge 0 - 101 kPa (0 - 760 mmHg, 30 in.Hg) to the booster's engine vacuum supply, and maintain an engine speed that will deliver 66 kPa (500 mmHg, 20 in.Hg) vacuum.





5. With a feeler gauge, measure the clearance between the gauge body and the adjusting nut as shown.

Clearance: 0 - 0.4 mm (0 - 0.02 inch)

NOTE: If the clearance between the gauge body and adjusting nut is 0.4 mm (0.02 inch), the pushrod-to-piston clearance is 0 mm. However, if the clearance between the gauge body and adjusting nut is 0 mm, the pushrod-to-piston clearance is 0.4 mm (0.02 inch) or more. Therefore, it must be adjusted and rechecked.

6. If clearance is incorrect, loosen the star locknut, and turn the adjuster in or out to adjust.

NOTE:
- Adjust the clearance while the specified vacuum is applied to the booster.
- Hold the clevis while adjusting.

7. Tighten the star locknut securely.





8. Remove the special tool.

Brake Booster Length With Booster Removed:

9. Adjust the pushrod length as shown if the booster is removed.
10. Install the master cylinder.