Brake Booster; Pushrod Clearance Adjustment - Honda Prelude 1993 Service Manual

Brake Booster
Tests
Functlonal Test
1, With the engine stopped. depress the brake pedal
severaltimes, then depress the pedal hard and hold
that pressure fo. 15 seconds. lf the pedal sinks, the
master cylinder, brake line or a brake caliper is
taulty.
2. Start the engine with the pedal depressed. lf the
pedal sinks slightly, the vacuum booster is work-
ing. lf the pedal height does not va,y, the booster or
check valve is faulty.
Lesk T6st
1. Deprsss the b,ake pedal with the engine running,
then stop the engine. It the pedal height does not
vary while depressed for 30 seconds, the vacuum
booster is OK, lf the pedal rises, the booster is
taulty.
CAUTION: Do not try to disa$ombl€ th€ boosto..
Replac€ the boostor assembly with a new ono.
2. With the engine stopped, depress the brake pedal
several times using normal pr€ssure. When the
pedal is first depressed, it should be low. On con-
secutive applications, pedal height should gradual-
ly rise. lf the pedal position does not va,y, check
the booster check valve.
Check Valve Tost
1. Disconnect the brake booster vacuum hose at the
booster.
2. Stsrt the engine and let it idle. There should be
vacuum available. lf no vacuum is available. the
check valve is not working correctly.
Replace the check valve and retest.
CHECK VALVE
Pushrod Clearance Adjustment
NOTE: Master cylinder pushrod-to-piston clearance
must be checked and adjustments made, if necessary.
b€fore installing master cylinder.
1. Set the special tool on the master cylinder body;
push in the center shaft until the top ot it contacts
with the end of the secondary piston by turning the
sdjusting nut.
PUSHBOD ADJUSTMENT GAUGE
0TJAG -SD40100
ADJUS?ING NUT
MASTER CYLINOER
SECONDARY PISTON
Without disturbing the center shaft's position, in-
stall the special tool upside down on the booster.
Install the master cylinder nuts and tighten to the
specified torque.
Connect the booster in-line with a vacuum gauge
0-760
mm HS (O-30 in Hg) to the booster's
engine vacuum supply, and maintain a engine
speed that will deliver 500 mm Hg (2O in Hg)
vacuum.
With a feeler gauge. measure the clearance be-
tween the gauge body and the adjusting nut as
snown.
Cloaranc6:
C81s without ABS: O-0.4 mm {O-0.O2 in}
Car8 with ABS:
O-O.2 mm (O-O.01 inl
4 .
5 .
VACUUM GAUGE
0-760 mm Hg lO-3O in Hgl
(Commercially
Available)
15 N.m 11.5 kg-rn,
1 1 tb-ft}
ADJUSTING ]{UT
( c o n t ' d )
CENTER SHAFT
1 9 - 1 5