Vacuum Brake Booster: Adjustments

Fig. 7 Measuring Distance "B" Between Master Cylinder End Face & Piston:

Fig. 8 Measuring Distance "C" Between Brake Booster Mounting On Master Cylinder & End Face:

Fig. 9 Measuring Distance "D" Between Master Cylinder Mounting Surface & Pushrod End:

Fig. 10 Brake Booster To Primary Piston Clearance Dimension "A":

Fig. 11 Brake Booster Rod Adjustment Specifications:

Fig. 12 Adjusting Brake Booster Pushrod:

1. With master cylinder removed from vehicle, as described under COMPONENT REPLACEMENT AND REPAIR PROCEDURES/MASTER CYLINDER, proceed as follows:
a. Measure distance between master cylinder end face and the piston, Fig. 7. Position a square (straight scale) against edge of master cylinder, then measure and subtract thickness of the square to determine dimension B.
b. Find dimension C by measuring distance between brake booster mounting surface and the end face, Fig. 8.
c. Measure distance between master cylinder mounting surface and the pushrod end, Fig. 9. Find dimension D by subtracting the square's thickness from the measurement taken.
d. Find brake booster-to-primary piston clearance dimension A, Fig. 10, using the formula A = B - C - D. Refer to Fig. 11, for proper clearance specifications.
e. If dimension A is not as specified, adjust brake booster pushrod as shown Fig. 12.