Pontiac tempest 1968 Service Manual page 177

5 - 1 2
1968 P O N T I A C SERVICE M A N U A L
solution and to bleed brakes. In doing this, pump
brake fluid from wheel cylinder bleeder valves until
clear fluid flows from bleeder tube and then continue
until no air bubbles emerge from bleeder tube.
The dual master cylinder is designed and built to
satisfy individual brake system displacement r e ­
quirements (Fig. 5-6). Therefore, It is necessary
that the following basic rales be used when replacing
either a complete master cylinder or parts,
1. The two-letter identification stamp on the end of
master cylinder indicates displacement capabilities
of a particular cylinder. Master cylinder should only
be replaced with another cylinder bearing the same
two-letter identification.
2. The lengths of component pistons in a master
cylinder are c r i t i c a l factors i n displacement capa­
bilities of a master cylinder. Pistons are coded,
using rings or grooves in shank of piston. When
pistons are replaced, replacement piston must con­
tain same identification marks and same contour at
push rod end as piston which was removed.
3. The dual master cylinder, used with standard
brakes contains a rubber check valve and check valve
spring i n each outlet boss. No check valve is r e ­
quired for disc brakes and, therefore, the outlet boss
to the front brakes w i l l not contain a check valve and
spring.
MASTER CYLINDER
REMOVE
1. Disconnect brake lines from two outlets on
master cylinder and tape end of lines to prevent
entrance of d i r t .
2. Disconnect master cylinder push rod from
brake pedal.
3. Remove master cylinder from dash.
DISASSEMBLE
1. Remove master cylinder reservoir cover and
drain fluid. Pump fluid from master cylinder by
depressing push rod,
NOTE; A new type of retained push rod is used on
all standard brake applications.
2 . Pull boot from master cylinder, to uncover push
rod retainer.
3. The retainer has a small, depressed tab in the
side and may be pried up to release retainer. Tab
serves to hold retainer and push rod on master c y l ­
inder while I t Is being shipped. It Is not necessary
to bend tab down at reassembly as retainer is held
in place between master cylinder and dash when
master cylinder Is bolted to car.
MASTER CYLINDER USAGE CHART
USAGE
Master Cyl.
Ident. Stamp.
Bore
Size
Primary*
Piston Ident.
Secondary
Piston Ident.
Delco Moraine
Pontiac Std. - Power Drum &
Manual Drum
HU 1" No Rings or Grooves
Tempest - Power Drum &
Manual Drum
CT 1"
1 Ring or 1 Groove
F i r e b i r d - Power Drum &
Manual Drum
CT 1 ?T
1 Ring or 1 Groove
F i r e b i r d - Disc (Power
& Manual)
FR 1-1/8" 3 Rings or 3 Grooves
Tempest - Manual Disc
GD
1-1/8"
7 Rings or 7 Grooves
Tempest - Power Disc DW
1-1/8"
6 Rings or 6 Grooves
Bendix
Pontiac - Drum
HU 1" 716
Pontiac - Disc
YM 1-1/8 1 794
Pontiac - Heavy Duty
PP 1" 6213
* Number stamped on side of piston.