Assembly Of Vacuum Seal In Rear Shell; Assembly Of Plates Plunger And Diaphragm - Pontiac Grand Prix Service Manual

HEAVY DUTY POWER BRAKES
5C-5
FRONT PLATE
SQUARE RING SEAL
REAR D
RET
ALVE PLUNGER
REAR DIAPHRAGM
Fig. 5C-5 Diaphragms, Plates, Retainer and Plunger
2. Install new secondary seals, back to back, in grooves
on rear end of front piston. Dip seals in brake fluid
and lift them carefully into grooves with dull scribe.
Slide protector and primary cup onto nose of front
piston.
3. Stack front piston return spring and retainer on nose
of front piston and dip assembly in brake fluid. Slide
assembly to bottom of master cylinder bore. Press and
twist piston to ease cups past snap ring groove.
4. Dip new rear piston and spring assembly in brake
fluid and slide assembly into bore. Use scribe and
press piston to ease cups into bore.
5. Press in against rear piston with round-end rod to
compress return springs. Do NOT use screwdriver or
other sharp-edged tool since this will damage the push
rod seat inside the piston. Maintain pressure on piston
and use Tru-Arc pliers to install snap ring in groove
inside bore. Make sure snap ring is seated securely in
groove.
6. Maintain pressure on rear piston while installing
piston stop screw and new O-ring seal in port
underneath bore. Torque screw with 3/8" wrench to 40
lb. in.
7. Remove master cylinder from vise. Install reservoir
diaphragm and cover and plug ports, temporarily, to
prevent entry of dust or dirt.
ASSEMBLY OF VACUUM SEAL IN REAR SHELL
Place rear shell on block of wood, studs down, and
using seal installer J 22677, press new seal, plastic
bearing face first, into recess in rear shell. Top outside
flange of seal should be pressed .305" (approximately
5/16") below flat shell surface next to seal cavity (Fig.
5C-7).
ASSEMBLY OF PLATES PLUNGER AND DIAPHRAGM
(Fig. 5C-8)
1. Install front diaphragm on front plate.
2. Apply a light film of power brake lubricant to
outside surface of front plate and b b and liberally to
the seal in the center plate bore. Carefully guide center
plate and seal assembly, seal side first, onto front plate
hub using tool J 22733. (See Fig. 5C-8).