1998 HONDA CIVIC speed

System Description
Steering Pump (cont'dl
The flow control valve and sub-valve in the pump per-
forms the following steps @ through @ to control the
flow of fluid, that is to increase the discharge volume
when engine speed is low, and to decrease it when the
engine speed increases. The assistance thrust of the
steering gearbox changes in compliance with the
change in the discharge volume.
When the engine starts, fluid discharged from the
discharge port starts to flow through oil passage A,
the fixed orifice and the variable orifice to the steer-
ing gearbox. When the engine speed is extremely
low, the return port is closed by the flow control
Fluid pressure discharged from the discharge port
is applied to the top of the sub-valve, and the fluid
pressure that passed through oil passage A is applied
to the bottom of the sub-valve. When this happens,
the pressure difference between the ends of oil pas-
sage A, which is caused by the resistance oil passage
A when the fluid flows through the passage. is
applied to the sub-valve, However, the pressure dif-
ference applied to the sub-valve. that is the force
that pushes the sub-valve down, is too small to
overcome the spring force, and the variable orifice is
fully open when the engine speed is extremely low.
Because the fluid volume flowing through the fixed
orifice and variable orifice increases, a pressure dif-
terence is created between the ends of these ori-
fices, and it increases in proportion to the engine
speed. As the fluid pressure that passed the fixed
orifice and variable orifice is directed to the bottom
of the flow control valve. a pressure difference is
created between the top and bottom of the valve,
which pushes down the flow control valve and
opens the return port. As a result, pan of the fluid
discharged from the discharge port feturns to the
pump suction port, keeping the discharge volume
constant.
In this condition, the sub-valve does not move. and
the variable orifice stays fully open.
lo
trrtrrlo3
J
o
PUMP R.P.M.
To STEERING GEARBOXSUB.VALVE
To STEEnING GEARBOX
FLOW CURVE
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o,,-i^"l^tKzYt)91y ul3Yl
FLOW CONTNOL VALVE
su8-vALvE
ORIFICE
ToP
17-18
FLOW CONTROL VALVE

t
To STEERING GEARBOX
To STEERING GEAREOx
@ The fluid volume that flows thorough oil passage A
and the pressure djfference applied to the sub-valve
increase in proportion to the engine speed. The
sub-valve lowers overcoming the spring force, and
it stans to close the variable orifice to regulate the
discharge volume, When this happens, the fluid vol-
ume flowing to the steering gearbox decreases as
the engine speed increases. At the same time, the
flow control valve continues to control the fluid vol-
ume to the return Port,
@ As the engine speed increases funher, the pressure
difference at the sub-valve increases further as well.
The sub-valve then closes the variable orifice com-
pletely, regulating the discharge volume further.
When this happens, the fluid volume discharged
from the pump to the steering gearbox is regulated
and maintained at a given level until the engine
speed reaches the high speed range The flow con-
trol valve functions continues to control the fluid
volume to the return Port.
Pressure Relief
Pressure at the discharge side of the fixed orifice is
directed to the bottom of the flow control valve. When
the pressure builds up, the relief valve in the flow con-
trol valve opens to release the pressure at the bottom of
the valve. This allows the flow control valve to be
pushed back by the pressure difference, and the fluid
volume to the pump return port increases.
As explained above. the system keeps the pump dis-
charge pressure (relief pressure) from exceeding the
given level by controlling the volume of the fluid to the
pump relurn pon,
1.,DAMPING ORIFICE{Docreases excessiv€vibration in the valv6.)
17-19
)
RELIEF VALVE {Opan)
SUB.VALVE
FLOW CONTROL VALVE
/F ft>..\
'-€/K\A/A
o'.'to"5lo'#2"n af11\D7
FLOW CONTROL VALVE

Pressure Control
Low assist at higher speeds:
WhensteeringresistanceIsIow,suchaswhendrivingathighspeeds,orwhendrivingstraightahead,theinputshaftis
near or in the neutral position, so there is little or no fiow ro any of the power cylinder orifices. Most oI the feed pressure
fromthepumpisbypassedtothereservoir.Becauseofthis,thepressurestaysthesameinbothsidesofthepowercy||n-
der, resulting in low or no asslst
VALVE From PUMP
SECTION A-A
RETURN PASSAGElTo RESERVOIRI
POWER CYLINDER
STEERING GEARBOX
High assist at lower speeds:
When steering resistance is high. such as when driving at low speeds' or when turning the wheel wirh the vehicle
stopped,thedifference|nang|ecreatedbetweentheinputshaftandtheVa|veopensthef|uidpassageononeside,and
c|osesthefluidpassageontheotherside,ateachpairoforifices'Thef|uidpressureincreasesinthesideo|thepower
cy|inder|edbythe|argerf|uidpassage'Thisincreasedpressurepushesontherackpiston,a|lowingthesteeringwhee|to
be turned with light effort. on the other side of the power cylinder, the return passage opens allowing the steering tluid to
returnthroUghtheinputshafttothereservoir'Thef|uidpassagestothepowercy|inderautomatica||ychangeins|ze,
increasing as the steering resrstance increases. In other words, the passages become larger and power assist increases
when the steering effort would normally be high, (for example' when parking or making low speed turns)' and the pas-
sagesbecomesma||erandpowerassistdecreaseswhenthesteeringeffortwou|dnorma||ybe|ow,(forexamp|e,when
driving at high speeds or straight ahead).
FLUIO PASSAGE TO
POWER CYLINDER
/t=\\a!-4,))
=YjJ
RESERVOIR
SECTION A-A
l'
{High fluid Pressure}

Troubleshooting
General Troubleshooting
Check the following before you begin:. Has the suspension been modified in a way that would affect steering?. Are tire sizes, tire variety and air pressure correct?. lsthe steering wheel original equipment or equivalent?. lsthe powersteering pump belt properlyadiusted?
. ls steeringfluid reservoirfilledto proper level?. ls the engine idle speed correct and steady?
Hard Steering (Check the powor assist. se€ page 17-3o. lfthe torce is over 29 N (3.0 kgf, 6.6lbo, Procede with this troubleshootinq.)
Abnormallluid pressure
{fluid pressureis too high)
Faulty valve body unit
Relief pres-sure too low
Abnormal
Faulty llow control valve(Replace the pump es anassembly)
Ch€ck the feed snd return circuit lin€s ano nosebetw6€n the gearbox and pump for clogging andd€lormation.
Normal line and hose
Check the pump fluid pressure(soe page 17-34).l/easure steady-state tluid pres-s!re while idling with the bothvalves tully open.It should be 1.500 kPa (15 kgf/cmr,213 psi) or below.
Normal
Check th€ flow control vslve (see page 17-42).. Chock the valvo lor smooth movement in the hous-ing.. Check the reliefvalve for leaks.
Check the pump fluid pressure
{see page 17-34).Measure pump relief pressurewhile idling with the pressure con-trol valve Iully closed.It should be 6,400 - 7,400 kPa (65 -
75 kgflcm,,920 - 1,070 psi)
Normal relisf pressure
17-22
Go to page 17-23Faulty pump assembly

Troubleshooting
General Troubleshooting (cont'd)
Assist (excessively light steering) athigh speed.
Shock or vibration when wheel isturned to {ull lock.
Steering wheelwill not returnsmoothly.
lf the problem is not corrected byadiusting the rack guide, adjustthe front wheel alignment lseesection 181.
Check the rack guide for properadiustment (see page 17 33).
Check the rack guide for properadjustment (see page 17-33).
Rack guide is adjusted properly.
lfthe problem is not corrected byadjusting the rack guide, replacethe gearbox.Check the belt for slippage andaolust as necessary {see page11 32).
A and B cylinder lines are nor-mal, check wheel alignment (seesection 18).
Wheel alignment is abnormal,adjust as needed.
Wheel alignment is normal.Check the steering wheel opera-tion and power assist check {seepage lT-30).
It the measurements are out ofspecifications, adjust the ra ckguide.
lf the problem is not corrected byadjusting the rack guide, replacethe gearbox.
17-24

/
Uneven or rough steering
Steering wheel kicks back
during wide t!rns.
ll,
)
Adjust the rac* guide (see page 17-3).
lf the problem is not corrected bY
adjusting the rack guide, replace
the gearbox.
Adiust the belt tension. Feplace the
belt, il necessary (see Page 17 32).
lfthe engine stalls when the wheel
is turned while car is stopped or
moving at low speed, adjust the
idle spe€d (see section 11)
ldle speed low or erratic.
Check power sleering fluid level lf
the level is excessively low, check
lor leaks in the system. Add lluid
to the specified level.
Air in reservoir, or check Powersteering Iluid level.
lf ltuid level is OK, check O-rings
and seals on both ends of thepump inlet hose, and the P/Spump housing mating surfaces
and the pumP shaft oil seal for
suction leaks. RePlace Parts as
nocessary.
Adjust the belt tension (see Page17 32)or replace belt.Pump belt sliPPing on PLrlleY(pump stops momentarilY)
Check if pump press{rre is normal
and the gauge needle travel is 500
kPa (5 kgl/cm?, 7l Psi) or less.
Chock the flow control valve if the
needle travel exceeds 500 kPa (5
kgflcm', 71 Psi). l{ the flow control
valve is normal, replace the PumPas an assemoly.
Install the power steering pressure
gauge, Close the Pressure contrcl
valve fully and m6ssure the PumPpressure {s€e page 17-34}.
17 -25,

Master Cylinder/Brake Booster
Pushrod Glearance Adjustment
NOTEr
. The master cylinder pushrod-to-piston clearancemust be checked and adjustments made, if neces_sary, before installing the master cylinder.. ABS type is shown, conventional brake type is similar.
1. Set the special tool on the master cylinde. body; push
in the center shaft until the top of it contacts the endofthe secondary piston by turning the adjusting nut.
Without disturbing the center shaft's Dosition, installthe specialtool upside down on the booster.Install the master cylinder nuts, and tighten to thespecified torque.
Connect the booster in-line with a vacuum gauge O _
101 kPa (0 - 760 mmHg, 30 in.Hg) to the booster,sengine vacuum supply, and maintain an enginespeed that will deliver 66 kpa (500 mmHg, 20 in.Hg)vacuum.
With a feeler gauge. measure the clearance Detweenthe gauge body and the adjusting nut as shown.
Clearance: 0 - 0.4 mm {0 - 0.02 in)
VACUUM GAUGE(Comm€rcially availeblel0 - 101 kPa{0 - 760 mm Hg, 30 in.Hg)
AOJUSTING NUT
FEELER GAUGE
19-22
10.
NOTE: lf the clearance between the gauge bodyand adjusting nut is 0.4 mm (0.02 in), the pushrod-to-piston clearance is 0 mm. However, if the clear_ance between the gauge body and adjusting nut is0 mm, the pushrod-to-piston clearance is 0.4 mm(0.02 in) or more. Therefore, it must be adjusted andrechecked.
6. lf clearance is incorrect, loosen the star locknut, andturn the adjuster in or out to adjust.
NOTE;
. Adjust the clearance while the specified vacuumis applied to the booster.. Hold the clevis while adjusting.
Tighten the star locknut securely.
Remove the special tool.
0 - 0.4 mm (0 - 0.02 in)
7.
ADJUSTERPUSHRODADJUSTMENT GAUGE07JAG - SD('1(x)
9. Adjust the pushrod length as shown if the boosterrs removed.
STAR LOCKNUT22 N.m{2.2 kg,f.m, 16lbtft)
11610.5 mm{{.571 0.02 in)
PUSHRODLOCKNUT15 N.m 11.5 kgf.m, 11 tbtftl
Install the master cylinder {see page l9-21).

Anti-lock Brake System (ABSI
Featu res/Construction
When the brake pedal is depressed during driving, the wheels can lock before the vehicle comes to a stop, In such a case,the maneuverability of the vehicle is reduced if the front wheels are locked, and the stability of the vehicle is reduced if therear wheels are locked, creating an extremely unstable condition. The ABS precisely controls the slip rate of the wheels toensure the grip force of the tires. and it thereby ensures the maneuverbility and stability of the vehicle.Judging the vehicle speed. the ABS calculates the slip rate of the wheels based on the vehicle speed and the wheel speed,then it controls the brake fluid pressure to attain the target slip rate.
Grip Force of Tire and Road Surlace
COEFFICIENT OFFRICTION
TARGET SLIP RATE
Slip Rate
BRAKINGSTART POINT
ROTATIONALDIRECTION
RADIALDIRECTIONOF THEROTATIONALOIRECTION
A: Distance without slio8: Slippsd distanceC: Actuel distance
sr-rrmre=f=SLIP RATEVEIIICLE SPEED - WHEEL SPEEOVEHICLE SPEED
19-46