Pontiac tempest 1968 Service Manual page 209

5C-6
1968 P O N T I A C SERVICE MANUAL
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 screw­
driver 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. Install piston stop screw and new O- ring seal
in port underneath bore. Torque screw with 3/8"
wrench to 40 lbs. in.
7. Install new spring and check valve in both outlet
ports unless master cylinder is to be used on disc
brake equipped vehicle. Press new tube seat into
each port using spare tube nut. Make sure tube seat
is bottomed in port. Torque tube nut to 40 lbs. in.
to be sure tube seat is bottomed in port.
8. 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
(Fig. 5C-7J
Place rear shell on block of wood, studs down, and
press new seal, plastic bearing face first, into re­
cess in rear shell. Top outside flange of seal should
be pressed .305" (approximately 5/16") below flat
shell surface next to seal cavity.
ASSEMBLY OF PLATES PLUNGER AND DIAPHRAGM
(Fig.
5C-4)
Install front diaphragm on front plate. Apply a
light film of power brake lubricant to outside surface
of front plate hub 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. Apply power brake lubricant
lightly to front and rear bearing surfaces of valve
plunger, being careful NOT to get any lubricant on
rubber grommet inside plunger.
Assemble valve plunger return spring on valve
plunger as shown and set spring and plunger in re­
cess of front plate hub, grommet side up. Place
vacuum seal firmly against shoulder on outside of
front plate hub. Set rear plate, threaded bore down,
over valve plunger and, using hands only, screw
rear plate onto front plate hub. To tighten plates,
place 1-1/16" hex bar stock or tool J-22839 in vise
and set plate assembly, front plate down, on hex
bar. Using air channel slot or rear plate edges,
hand torque plates to 12 1/2 lb. ft. Remove plate
assembly from vise. Install rear diaphragm on rear
plate and over lip of center plate. Assemble rear
diaphragm spring retainer over rear diaphragm and
lip of center plate. Using fingers, press retainer
onto center plate until it seats against shoulder of
center plate.
ASSEMBLY OF DIAPHRAGMS AND PLATES IN FRONT
AND REAR SHELLS (Fig. 5C-3)
Apply power brake lubricant liberally to bearing
seal in rear shell. Apply power brake lubricant
liberally to scalloped cut-outs on edge of front shell.
When assembling diaphragm and plate assembly in
rear shell, the rear diaphragm and center plate lugs
must be aligned between lances on rear shell. Care­
fully guide valve housing sleeve through bearing seal
in rear shell, keeping diaphragm and plates in cor­
rect alignment. Work outer rim of front diaphragm
into rear shell so that outer rim of front diaphragm
is under each of retaining lances on rear shell.
1. Secure power section front shell to tool J-8433
and J-6407-02 as in Fig. 5C-3.
2. Assemble rear shell to spanner wrenches
J-9504 as shown in Fig. 5C-3
0
3. Secure front shell to arbor press.
4. Place power diaphragm return spring in front
shell, small coil first.
5. Position rear shell, spanner wrenches, and tool
J-22553-1 over spring so that scribe marks will be
aligned when the shells are locked together.
6. Slowly compress assembly keeping in a parallel
plane.
7. When front and rear shells are mated rotate
spanner wrenches until the two shells are locked
together.
CA UTION: Do not compress assembly to the point
of damaging power unit.
8. Release pressure from assembly and remove
all tools from front and rear shells.