Servo Push Rod - Measurement/Adjustment

BULLETIN NUMBER
SB95-09-L001

ISSUE DATE
APRIL 1995

GROUP
BRAKES

PICKUP (TF) VACUUM SERVO PUSH ROD MEASUREMENT/ADJUSTMENT
(WORKSHOP MANUAL CORRECTION)

Affected Vehicles

All 1988-95 Pickup (TF) models.

SERVICE INFORMATION




The procedure for measuring/adjusting the vacuum servo push rod, when replacing either the vacuum servo or the master cylinder, is incorrectly described in the Workshop Manuals:

This Service Bulletin contains correct vacuum booster push rod measurement/adjustment procedures for the affected vehicles.

SERVICE PROCEDURE

Vacuum Servo Push Rod Measurement/Adjustment Procedure

1. Apply 500 mmHg (19.7 in.Hg) of negative pressure to the vacuum servo.




2. Use a scale to measure the push rod length (push rod-to-flange face dearance) (Figure 1).

Note
Push Rod Length: 18.2 mm (0.717 in.).

3. If the push rod length is not equal to the above specification, it must be adjusted.




(1) Measure the brake pedal height after making sure that the pedal is fully returned by the pedal return spring (Figure 2).

Note
The pedal height (L2) must be measured after starting the engine and revving it several times. All measurements must be taken from a bare floor (carpet and floor mat removed).

Pedal Free Play: 6 - 10 mm (0.23 - 0.39 in.).
Pedal Height: 174 - 184 mm (6.85 - 7.24 in.).

Pedal height (L3) must be 95 mm (3.7 in.) or more when about 50 Kg (110.25 lb.) of stepping force is applied.

Pedal free play (L1) must be measured after turning off the engine and stepping on the brake pedal firmly five times or more.

(2) If the measured value is not within the above range, adjust the brake pedal as follows:

a) Disconnect the stop light switch connector.

b) Loosen the stop light switch lock nut.

c) Rotate the stop light switch so that it moves away from the brake pedal.

d) Loosen the lock nut on the push rod.

e) Adjust the brake pedal to the specified height by rotating the push rod in the appropriate direction.

f) Tighten the lock nut to 15 ft.lb.




g) Adjust the stop light switch to the specified clearance (between the switch housing and the brake pedal) by rotating the switch housing (Figure 3).

Note
Clearance: 0.5- 10 mm (0.02 - 0.04 in.).

IMPORTANT
Do not attempt to force the push rod into position during the stop light switch installation and adjustment procedure.

h) Tighten the stop light switch lock nut.

i) Connect the stop light switch connector.