Power Brake Assist: Testing and Inspection

Fig. 1 Fabricated Brake Unit Adapter:

1. Use fabricated adapter, Fig. 1, connect special vacuum gauge tool No. 201 589 13 21 00, or equivalent, to vacuum line between brake booster and check valve.
2. Connect special Teves pressure tester tool No. 3 9305-1020.4, or equivalent, to brake caliper at vent screw, then bleed pressure tester.
3. Connect special Bosch pedal force meter tool No. 0 681 148 EFSV 57 B, or equivalent, to brake pedal.
4. Start and operate engine until 10.7-11.4 psi vacuum is present by accelerating, then quickly releasing accelerator pedal.
5. If low vacuum or decreasing vacuum is indicated, check following:

a. Vacuum line leak.
b. Faulty check valve.
c. Faulty seal between booster and master cylinder.
d. Faulty brake unit control housing seal, if seal is faulty brake unit must be replaced.

6. Measure line pressure at specified brake pedal force.

Brake Pedal Force, Ft. Lbs. 37
Girling LSC 50, psi 71-156
Girling LSC 80, psi 142-228
Teves T52/225T, psi 28-171
Teves 52/4A/225-210, psi 142

Brake Pedal Force, Ft. Lbs. 74
Girling LSC 50, psi 284-441
Girling LSC 80, psi 370-498
Teves T52/225T, psi 398-569
Teves 52/4A/225-210, psi 356

Brake Pedal Force, Ft. Lbs. 111
Girling LSC 50, psi 498-711
Girling LSC 80, psi 611-768
Teves T52/225T, psi 768-967
Teves 52/4A/225-210, psi 597

Brake Pedal Force, Ft. Lbs. 148
Girling LSC 50, psi 768-924
Girling LSC 80, psi 839-995
Teves T52/225T, psi 1138-1379
Teves 52/4A/225-210, psi 839

Brake Pedal Force, Ft. Lbs. 184
Girling LSC 50, psi 995-1081
Girling LSC 80, psi 1067-1209
Teves T52/225T, psi 1493-1778
Teves 52/4A/225-210, psi 1067

Brake Pedal Force, Ft. Lbs. 221
Girling LSC 50, psi 1138-1166
Girling LSC 80, psi 1223-1351
Teves T52/225T, psi 1877-1991
Teves 52/4A/225-210, psi 1280


7. If line pressure is ±140 psi from specifications, replace brake unit.
8. Remove test equipment, then bleed brake system at which pressure tester was connected.