Subaru 1600 Service Manual page 456

Pedal force gauge
Adaper hose
Fig. 10-62 Connection of gauges
a. Air tightness check
(l) Start engine and keep it running
until a vacuum of 66.7 kPa (500
mmHg. 19.69 inllg) is indicated
on vacuum gauge. Do not depress
b rake pedal.
(2) Stop engine and watch the gauge.
I f the vacuum drop range is less
than 3.3 kPa (25 mmHg, 0.9i1
inHg) within 15 seconds after
stopping engine, brake booster is
functioning properly.
If defective. the cause may be one of
those listed below.
• Check valve malfunction
• Leak from vacuum hose
• Leak from the shell jointed portion
or stud bolt welded portion
• Damaged diaphragm
• Leak from valve body seal and
bearing portion
• Leak from plate & seal ASSY
portion
• Leak from poppet valve ASSY
portion
b. Loaded air tightness check
(I) Start engine and depress brake
pedal with pedal force of 196 N
(20 kg, 44 Ib). Keep engine run·
ning until a vacuum of 66.7 kPa
(500 mmHg, 19.69 inHg) is indi-
cated on vacuum gauge while the
pedal is still depressed.
(2) Stop engine and watch vacuum
BRAKES
Pressure gauge
Pressure gauge
~
Adapter hose
A17·252
gauge.
I I' th e vacu urn drop range is less
than 3.3 kPa (25 mmHg, 0.98
inHg) within 15 seconds after
stopping engine, brake booster is
functioning properly.
If defective, refer to a. described
above.
c. Lack of boosting action check
Turn off engine, and set the vacuum
gauge reading at "0". Then, check the
fluid pressure when brake pedal is
depressed. The pressure must be
greater than the standard value listed
below.
~~~I-force
TFIUid pressure
! N (kg, Ib) kPa (kg/cm
2
,
psi)
I
~ 47(115'33)
- - - - -- ----+----------1
294 (30, 66)
------ ---------
392 ( 4, 57)
2,550 (26, 370)
d. Boosting action check
Set the vacuum gauge reading at
66.7 kPa (500 mmHg, 19.69 inHg) by
running engine. Then, check the fluid
pressure when brake pedal is depress-
ed. The pressure must be greater than
the standard value listed below.
10-19
Pedal force
Fluid pressure
N(kg,lb)
kPa
(kgl
cm
2
,
psi)
147 (15, 33)
3,432 (35, 498)
For 152.4 mm
(6 in) booster:
294(30,66)
5,884 (60, 853)
For 177.8 mm
(7 in) booster:
6,865 (70,995)
5. Handling Precautions
I) After protector has been removed
from push·rod, do not turn the master
cylinder side of brake booster down-
wards.
a. If the master cylinder side is turned
downwards, push-rod may come
loose by virtue of its own weight,
and reaction disc may drop into
brake booster.
b. Whether or not reaction disc has
dropped can be determined by
measuring the dimension
"Q".
The projected amount
"Q"
of push-
rod should be as follows:
Standard (Correct):
Q:
10 mm (0.39 in)
Incorrect:
Q :
5.5 mm (0.217 in)
A 17·253
Fig. 10-63 Push rod projection
c. I f protector is fitted correctly,
reaction disc will not fall out.
2) Be careful not to drop brake
booster. Brake booster should be dis-
carded if it has been dropped.
3) Use special care when handling
operating rod.
If excessive force is applied to operat-
ing rod, sufficient to cause a change in
the angle in excess of ±3°, it may
result in damage to the power piston
cylinder.
4) Use care when placing brake
booster on the floor.