Chevrolet 1980 Light Duty Truck Repair Manual page 138

5-2 BRAKES
housing and rem ove the power piston bearing from the
center opening o f the rear housing.
Power Piston Group (Fig. 5-2A)
1. R em ove reaction retainer and piston rod from the
power piston.
2. R em ove the power head silencer from the neck o f
the power piston tube.
3. Turn power piston group upside down so that end
o f push rod is against a hard surface. Grasp entire power
piston group w ith both hands and use slight force or impact
on push rod to rem ove diaphragm retainer.
4. R em ove diaphragm s, support plates and divider
from the power piston. R em ove center bearing from housing
divider.
5. Separate both the
diaphragm s from the support plate.
6. U sing a screwdriver, rem ove reaction body retainer.
7. R em ove reaction body.
O V E R H A U L M A N U A L
F ig . 5 - 2 A - - P o w e r P is to n G r o u p - E x p lo d e
primary and secondary
8. R em ove reaction disc and reaction piston from the
center o f reaction body by pushing dow n on the end o f the
reaction piston with a small blunt punch.
9. R em ove air valve spring.
10. R em ove the rubber reaction bumper on the end o f
the air valve.
11. U sing Truarc N o. 2 pliers (J-4880 or equivalent)
rem ove the retaining ring from the air valve.
12. R em ove the air filter from the tubular section o f
the power piston.
13. R em ove the air valve push rod assembly from the
push rod end o f the power piston. The follow ing rem oval
m ethods are recom m ended.
a. Place the power piston in an arbor press and press
the air valve push rod assembly out o f the bottom o f the
power piston tube with a rod not exceeding 1/2" in
diameter.
b. A n alternate m ethod w ould be the use o f a heavy,
round shanked screwdriver. Insert screwdriver on both sides
o f the push rod, and pull the air valve push rod assembly