Page 609 of 1413

I
Rcf. No. I Tool Numb€lDcscriptionO'ty I P!9. Relrrrncc
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07GAF - PH70100
07GAF - SD40700
07GAG - SD40100
07GAG - SD40200
07GAG - SD40400
07JGG - 0010104
07MAC - 5100200
07MAG - 5100100
07NAD - SR30200
07NAG - SR30900
OTNAK - SR3O11A
OTNAK - SR3O12A
07406 - 0010001
07406 - 0010300
07405 - 0010400
07725 - 0030000
07746 - 0010100
07746 - 0010200
007i$ - 0010000
07916 - SA50001
07947 - 6340500
07974 - 6890801
0797,1 - SA50200
Pilot Collar
Hub DivAssembly Base
Piston Seal Ring Guide
Piston Seal Ring Sizing Tool
Cylinde. End Seal cuide
Belt Tension Gauge
Ball Joint Remover, 28 mm
Ball Joint Boot Clip Guide
Cylinder End Seal Remover Attachment
Valve Ssal Ring Sizing Tool
P/S Joint Adapter (Pump)
P/S Joint Adapter (Hos6)
P/S Pressure Gsuge
Pressure Control Valve
Pressure Gauge
Universal Holder
Attachment, 32 x 35 mm
Attachment, 37 x 40 mm
Driver
Locknut Wrench, i[0 mm
Driver Anachment
Cylinder End Seal Slider
Sleeve Sesl Ring Sizing Tool
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'17 -52
17-39
17 -57
17 -57
17-EO
17 -20't7 -15
17-50
17-5{
17 -22
17 -22't1-22
17 -22
17-35, 53
17-55, 56
17 -1'l
t7-55
17 -2'l
17 -11
17-57,58
17-55
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17-2
Page 611 of 1413
System Description
Fluid Flow Diagram
The system is a compact rotary-valvs-type power stssring, connocted to the st€oring gearbox. Th6 fluid pressure is pro-vided by a vane-type pump which is driven by the engine crank pulley. The amount of fluid and pressurs is regulsted bythe flow control valve built into ths pump, The fluid prssaurs from th6 pump is dolivsred to tho valve unit sround the pin-ion of the steering g€arbox. The vslv€ inside the valvs unit controls the hydraulic prossur€ End changos the direction otthe flow. The fluid then flows to the power cylinder, where rack thrust is gen6rat6d. Fluid returning from th6 powsr cylin-der flows back to the .eservoir, where the fluid is 'filtered" and supplied to the pump Egain.
17-4
Page 615 of 1413

System Description
Steering Gearbox
The rack-and-pinion type steering gearbox has a valve unit incorporated with the pinion to control the steering fluid pres-
sure. Steering fluid from the pump is regulated by a rotary valve in the valve unit and is sent through the cylinder pipe to
the power cylinder, where hydraulic pressure is applied. The steering fluid in the other side of the power cylinder returns
through the cylinder pipe and valve unit to the reservoir.
VALVE UNIT
CYLINDER PIPE
POWEB CYLINDER
Valve Unit
Inside the valve unit is the valve, which is coaxial with the pinion shaft, and controls the steering fluid pressure. The valve
housing is connected with the fluid pipe from the pump, return pipe to the pump, and the two cylinder pipes from the
respective power cylinder.
The pinion shaft is double - structured with the input shaft connected to the pinion gear, both of which are interconnected
with the torsion bar.
The pin insened in the valve and the pinion shaft groove engage; this allows the pinion shaft to rotate together with the
Because of this construction, the difference in angle in the circumferential direction between the input shaft and the valve
becomes larger according to the torsional strength of the pinion or steering resistance. However, maximum torsion
between the shafts is regulated by the engaged splines of the shafts at the pin engagement section to hold the torsion bar
within the set value.
This allows the steering system to lunction as an ordinary rack-and-pinion type steering if the steering fluid is not pressur-
ized because of a faulty pump.
VALVE
Difforcnco in .ngl. bo{w€cn thainput shalt rnd pinion !h.tt
ln-1
B
lEngag€ with the pinionshaft groove)
17-8
INPUT SHAFT
Page 616 of 1413

Pressure Control
Low assist at higher speeds:
When steering resistance is low. such as when driving at high speeds. or when driving straight ahead, the input shaft is
near or in the neutral position, so there is little or no flow to any of the power cylinder orifices, Most of the feed pressure
trom the pump is bypassed to the reservoir. Because of this, the pressure stays the same in both sides of the power cylin-
der, resulting in low or no assist.
vaz =- S\->/-\7/RETURN PASSAGE(To RESERVOIRI
VALVE UNITINPUT SHAFT
High assist at lower speeds:
When steering resistance is high, such as when driving at low speed, or when turning the wheel with the car stopped, the
difference in angle created between the input shaft and the valve opens the fluid passage on one side, and closes the fluid
passage on the other side, at each pair of orifices. The fluid pressure increases in the side of the power cylinder fed by the
larger fluid passage. This increased pressure pushes on the rack piston, allowing the steering wheel to be turned with light
effon. On the other side of the power cylinder, the return passage opens allowing the steering fluid to return through the
input shaft to the reservoir. The fluid passages to the power cylinder automatically change in size, increasing as the steer-
ing resistance 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 passages become smaller and
power assist decreases when the steering effort would normally be low, (for example, when driving at high speeds or
straight ah€ad).
FLUIO PASSAGE TOPOWER CYLINDERFrom PUMP
A
/t-:\
v"
=iJ
RETURNPASSAGE
FLUID PASSAGE FROMPOWER CYLINDER
ALVE F.om PUMP
RESERVOIR
Page 619 of 1413

Troubleshooting
General Troubleshooting {cont'd}
Assist (excessively light steering) athigh speed.
Shock or vibration when wheel isturned to tull lock.
Wheelwill not return smoolhly.
ll the problem is not corrected byadjusting th6 rack g!ide. adjustthe front wheel alignment (see
section 18).
Check the rack guido proper ad'justment (see pago 17-21).
Check the rack guide tor properadjustment (ses psge 17-21).
Rack guide is adjusted prop€rly.
lf th€ problem is not correct€d byadiusting the rack guide, roplacethe gesrbox.Ch6ck the belt tor slip and adjustas nocessary (see page 17-20).
lf oither one or both of the cylin-der pip€ A and B is/are deformed,rsplace,
lf the cylinder pip6 A and B arenormal, remove the gearboxfrom th€ f.ame and mossure thepinion torqug on the gearbox.
It should be 0.7 - 1.2 N.m {7 - 12kgf.cm, 6 - 10 lbf.in) or belowwith the sleering rack in thestraight ahead driving position.
lf lhe measurem€nts are out ofspecilications. adjust the rackguid6.
ll ihe problem is not corrected byadjusting the rack guide, replaceihe gearbox.
17-12
Page 621 of 1413

Troubleshooting
Noise and Vibration
NOTE: Pump noise in first 2 - 3 minutes after starting in cold weather (-20.C, -4"F or colder) is normal.
Humming
Rattle or chattering
Right cylinder end soal squeak
Pump noise. though not loud,lrom the vslvo bodv unit can be heard when turn-ing the steering wheel right or left. This is normsl.
Humming due to pulsation ol fluid is no.mal, paniculady when wheel is turnedwith ca. stopped.
lf equipped with automatic trans-mission, the hum could b€ tor-que convener or pump notse.
Confirm by temporarily removingpump b€lt.
High pressure line touching theframe,Reposhion tho line.
Loose steering shaft connector.tie-rod, or balljoint.Check and tighten, or replacepa s as necessary.
Column shaft wobbling.Replace column assembly.
Check the rack guide for properadjustment (16o page 17-21).Adjust, if n€ca€ssry.
Rattling sound and feeling when turning the steoring wheel right and lett with thoengine OFF is a sound when th6 valve unit contacts tho stopper. This is normal.
Striking sound wh6n turning the ste€ring whoglfully right o. left is a sound whenthe r6ck end contacts th6 stopper. This is normal.
17-14
Page 623 of 1413

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.Roplace the valve oil seal fromthe valve housing.
Leaking from cylinder end intoleft tie'rod boot.Replace the valve oil seal lromthe pinion shaft.
Reolace the cvlinder end seal.
Leaking from cylinder end intoright tie rod boot.
Tighten attaching bolts or replacethe valve body unit or gear hous-Ing.
Leaking from the vslve bodyuniVhousing mounting soction.
Tighten connector. It still leaking.replace the pipe, cylinder orvalve housing unil.
Leaking from cylind6r pipe A or Bconnection (at tlare nut).
Leaking caused by damaged cy-linder pipe A or B.Replace the cylinder pipe A or B.
Leaking from feed pip6 andreturn pipe of the valve body unit(at flare nut).
Tighten connector. lI still leaking,replace the pipe or valve housIn9,
17-16
Page 653 of 1413
Steering Gearbox
Removal (cont'dl
Remove the return pipe clamp from the left side of
the rear beam. and move the return piDe above the
steering gearbox.
Remove the rear beam brace.
Remove the left tie-rod end, then slide the rack
the way to the right.
11.
12.
RETURN PIPE CLAMP
13.
I.TFT TIE-ROD END
14. Disconnect the two lines from th€ valve bodv unit
on the steering gea.box.
CAUTION: Aftor dkconnccting tho ho3o and pip.,
plug or r.d thc ho3. rnd pipc whh I pioco of tapo
or .quivll.nt to prcvont torcign m!tori!|3 f.om
ritrdng thc vdv. body unit.
NOTE:
. Place the pipe disconnected in the previous step
at the rear side of the gearbox so that they do
not hinder in the gearbox removal.
. Do not loosen the cylinder pipes A and B be-
tween the valve body unit and cylinder,
RETUR]T HOSE
15. Remove the steering gearbox mounting bolts.
GEARBOX MOU NNG BOLTS
17-46