1999 HONDA CIVIC steering

Steering Gearbox
Installation (cont'dl
Center the cable reel by first rotating it clockwise
until it stops. Then rotate it counterclockwise(approximately two turns) until the arrow mark on
the label points straight up. Reinstall the steering
wheel (see page 17-35).
Install the steering joint cov€r with the clamps and
clrps.
7.
STEERING JOINI COVER
17-14
9. Reconnsct the ti€-rod ends to the steering knuckles,
thon tightsn th€ castle nut ('96 -'97 models) or nut('98 -'00 models) to the specified torque, and install
new cotter pins.
NOTE: Before connecting the tie-rod ends, wipe off
any grease contamination from the ball joint
tapered section and threads.
CAUTION: Torque lhe ct3tle nut to thr lowsr torque
spocification, th€n tighton it only tar anough to
align the 3lot with tho pin hob. Do not align the
nut by loosening ('96 - '97 modcls onlyl.
TIE.ROD
COTTER PINSR6plac6.On rgassombly, b6nd
'96 - 37 model3:
cotter prn as shown.'98 - '00 modol3:
NUT4a N.m(4.5 kgf.m,33 lbr.ftl
CAST1T NUT,O - ilt N'm{4,0 - 4.8 kgf.m.29 - 35 tbtftl
10.Installthe exhaust pipe A or TWC (see section 9).
Connect the shift linkage (see section 13 or section
14).
Install the front wheels.
After installation, perform the following checks.
. Adjust the front toe (see section 18).. Check the steering wheel spoke angle. Adjust by
turning the right and left tie-rods, if necessary.
NOTE: Turn the right and left tie-rods equally.
ll.

Component Locations
I
lndex
Power Steering:
NOTE:
. li an intact airbag assembly has been removed trom a scrapped vehicle or has been found defective or damaged dur-
ing transit. storage or service, it should be deployed (see section 24).
. Before removing the gearbox, remove the driver's airbag assembly and steering wheel.
. After installing the gearbox, checkthewheel alignmentand adjust if necessary.
SRS components are located in this area. Review the SRS component locations. precautions, and procedures in the SRS
section {24} before performing repairs or service.
STEERING WHEELRemoval/lnstallation, page 17-35
Disassembly/Feassembly, page 17-36
DRIVER'S AIRBAG ASSEMBLYRemoval/lnstallation, see section 24
STEERING GEAREOXRack Guide Adiustment, page 17'33
/
Removal, page 17 47Disassembly, page 17-49Reassembly, page 17-55Installation, page 17-65VALVE EODY UNITOverhaul, page 17 52
COLUMNFemoval/lnstallation, page 17-37Inspection, page 17-38CASLE REELRemoval/lnstallation, see section 24
IGNITION SWITCHSee section 23
POWEF STEERING PUMPPump Belt Inspection, page 11-32Pump Belt Adiustmenl, page 11'32Pump Pressure Check, page 17 34Removal/lnstallation, page 17'40Disassembly/Reassembly, page 17-41
TIE.ROD END BALL JOINTBallJoint Boot Replacement, page 17-68
1,,
17-15

System Description
Fluid Flow Diagram
The system is a compact rotary-valve-type power steering, connected to the steering gearbox. The fluid pressure is pro-
vided by a vane-type pump which is driven by the engine crank pulley. The amount of fluid and pressure is regulated by
the flow control valve built into the pump. The fluid pressure from the pump is delivered to the valve body unit around the
pinion of the steering gearbox. The valve inside the valve body unit controls the hydraulic pressure and changes the direc-
tion of the flow. The fluid then flows to the power cylinder. where rack thrust is generated. Fluid returning from the power
cylinder flows back to the reservoir, where the fluid is "filtered" and supplied to the pump again.
RESERVOIR
VALVE BOOY UNIT
SUB.VALVE
FLOW CONTROL VALVESTEERING GEARBOX
17-16

)
Steering Pump
Construction
The pump is a vane-type incorporating a flow control valve (with an integrated relief valve) and is driven by a POLY-V-belt
from the crank pulley. The pump features 10 vanes. Each vane performs two intake/discharge operations for every rota-
tion of the rotor. This means that the hydraulic fluid pressure pulse becomes extremely small during discharge.
/
ROTORVANE CAM RING
Operation
The belt-driven pulley rotates the rotor through the drive shaft. As the rotor rotates, the hydraulic pressure is applied to
the vane chamber of rhe rotor and the vanes will rotate while being pushed onto the inner circumference of the cam ring.
The inner circumference of the cam ring has an extended portion with respect to the center of the shaft, so the vanes
move downward in the axial direction as the rotor rotates. As a result of this roller movement. the internal volume of the
vane chamber will change, resulting in fluid intake and discharge
START OF FLUID INTAKE:FLUID INTAKE:FLUID MOVEMENT:FLUID DISCHARGE:
The vanes are pushed ontothe inner circumference ol the
cam ring,
lhe volume ofthe vane cham- The sucked-in fluid moves
ber increases so that fluid is toward the discharge port.
sucked in.
As the vanes return to the
their original Position on theinner side, the volume of the
vane chamber decreases so
the fluid is discharged from
the discharge port.
(cont'd)
a-t 4-I I- | t
FLOW CONTROL VALVE
J

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
!rs+/f/ffih\
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

System Description
Steering Gearbox
The rack-and-pinion type steering gearbox has a valve body unit incorporated with the pinion to control the steering fluidpressure. Steering fluid from the pump is regulated by a rotary valve in the valve body unit and is sent through the cylin,der line to the power cylinder, where hydraulic pressure is applied. The steering fluid in the other side of the power cylin,der returns through the cylinder line and valve body unit to the reservoii.
VALVE EODY UNIT
CYLINDER LINE
To RESERVOm +-From PUMP -;
POWER CYLINDER
Valve Body Unit
Inside the valve body unit is the valve, which is coaxial with the pinion shaft, and controls the steering fluid pressure. Thevalve housing is connected with the fluid line from the pump, the return line to the reservoir, and the two cylinder linesfrom the respective power cylinder. The pinion shaft is double - structured with the input shaft connected to the piniongear, both of which are interconnected with the torsion bar.
The pin inserted in the valve and the pinion shaft groove engage; this allows the pinion shaft to rotate together with thevalve. Because of this construction, the difference in angle in the circumferential direction between the input shaft and thevalve becomes larger according to the torsional strength of the pinion or steering resistance. However, maximum torsionbetween the shafts is regulated by the engaged splines of the shafts at the pin engagement section to hold the torsion barwithin the set value,
This allows the steering system to function as an ordinary rack-and-pinion type steering if the steering fluid is not pressur-
ized because of a faulty pump,
VALVE
Difforence in angle botwoon theinput shaft and pinion shsft
PINION SHAFT
lo
INPUT SHAFT
-l
a
17-20
INPUT SHAFT

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}