1999 HONDA CIVIC Gear

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}

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,

)
Pump noaseGrating noisefrom pump
Pump gear nois€
Check the tluid level.
lf low, fill the reservoir to the
proper level, and check lor leaks.
Tighten or replace as nocessary.
Cavitation caused bY air bubbles
in the fluid.
Check lor a crushed suction hose
or a loose hose clamp allowing
air into the suction side of the
sy$em.Tighton or roplace as necossary.
NOTE: Pump noise uP to 2 - 3
minutes alter starting in cold
weather is normalCompare pumP noise at operating
temperature to simular vehicle.
lf pump nois€ is abnormallY loud,
remove and inspect the PUmP for
w6ar and damage (see Page 17-
41).
lz/
Rattle or chattgring
17-27
Tighten or replace the Pulley.lf shatt is loose, rePlace thepump.
tr

Troubleshooting
Fluid Leaks
Check the gearbox assembly for oil leaks carefully. Oil can leak out of various points. depending on location of thefaulty oil seals/seal rings. Check the following before removing the gearbox from the frame_
Steering GearboxLeaking from the oil seal on thetop of the valve housing.Replace the valve oil seal fromthe valve housing.
Leaking from cylinder end intoleft tie rod boot.Replace the valve oil seal tromthe pinion shaft.
Replace the cylinder end seal onthe gear housing side.
Leaking lrom cylinder end intoright tie-rod boot.Replace the cylinder end seal onthe cylinder end side.
Leaking lrom the shaft upper endsectron or pin engagement sec,tion ol the pinion shaft.Replace the valve body unit.
Tighten the connector. lf it's stillleakinO, replace the Iine, cylinderor valve housing unit.
Leaking from cylinder line A or Bconnections {at tlare nut}.
Leaking caused by a damagedcylinde.line A or B.Replace cvljnder line A or B.
Leaking from feed line and returnline ioint fitting on the valve bodyunit (at flare nut).
Tighten the connector. ll it's stillleaking, replace the line,,oint fit,ting or valv6 housing.
17-2a

Inspection and Adjustment
Steering Operation
Place the front wheels in the straight ahead position,
and measure the distance the steering wheel can beturned without moving the front wheels.
ROTATIONAL PLAY: 0 - 10 mm l0 - 0.39 inl
lf the play exceeds the service limit. perform rack guide
adjustment (see page 17-33).
lf the play is still excessive after rack guide adjustment.inspect the steering linkage and gearbox as describedon the nel(t pag€.
ROTATIONAL PLAY
17-30
Power Assist Gheck with
Vehicle Parked
1. Check the power steering fluid level (see page 17-33) and pump belt tension (see page 17-32).
2. Start the engine, allow it to idle. and turn the steer-ing wheel from lock-tolock several times to warm
up the fluid.
3. Attach a spring scale to the steering wheel. With theengine idling and the vehicle on a clean, dry floor,pull the scale as shown and read it as soon as thetires begin to turn.
The scale should read no more than 29 N (3.0 kgf.
6.6 lbf). lf it reads more, check the gearbox andpump,
D0