steering wheel MITSUBISHI ECLIPSE 1990 Service Manual

o-4GENERAL - Technical Features
BASIC CONSTRUCTION
The 4WD vehicles are equipped with
2.OL DOHC
16-valve turbocharged engine and incorporate new
technologies such as full time 4WD of center
differential type with viscous coupling differential
limiting for excellent running stability and excellent
Steering
l Light weight and compact rack and pinion
type for high steering response
l Tilt steering mechanism to give optimum
driving position
\driving across bad roads, and $-wheel independent
suspension for comfortable riding.
Adopted on
2WD vehicles are 2.OL DOHC 16-valveengine, MacPherson strut type front suspension
and torsion axle
typ.e 3-link rear suspension.
Rear suspension
l Self-aligning double wishbone type suspen-
sion for comfortable ride
(4WD)l Torsion axle type 3 link suspension for
outstanding driving stability
(2WD)l Negative chamber for outstanding steer-
ability during high speed driving
0 Anti-lift geometry for high stability duringbraking
lIntegral torsional bar type axle beam for
optimum roll stiffness (2WD)
\Front propeller shaft (3-piece
4-joint type)
lRobro joint to absorb lengthwise and angular
change and prevent transmission of vibrations.
(4WD)
IFront suspension
The front suspension of McPherson strut type
independent suspension system
l Under steer geometry for outstanding steering
stability
l Negative offset geometry for outstanding
stabil-ity at braking
0 Offset coil springs for comfortable ride
Brakes
l Cross piping dual type proportioning valvethat keeps balanced braking power even at
failure of the hydraulic system.
l Four wheel disc brake system for high
braking power.

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,
14-24FUEL SYSTEM - Sensors
POWER STEERING OIL PRESSURE SWITCHEngine control unit
Power steering oil
pressure switchBattery
voltage
6FUO5OtIWhen the steering wheel is turned and the oil
pressure of the power steering oil pump increases,
the power steering oifpressure switch sends an ON
signal to the engine control unit. The engine control
unit detects the oil pump load with this signal andactivates the idle speed control servo to control
theidle speed. Specifically, it prevents the idle
speecfrom dropping due to oil pump load, thus
ensuringstable engine idling.IGNITION
SWITCH
1IBattery
Ignition
switch
Starter motor
aS terminalcontrol unit
6FUO762The signal indicating that the ignition switch is ON,
OFF or cranking (ST) is input to the engine control
unit.
When the ignition switch ON signal is input to the
engine control unit, the unit energizes the control
relay coil to supply power to the sensors and
actuators.When the ignition switch ST signal is input to the
engine control unit, it determines that the engine
iscranking and controls the fuel injection rate,
despeed control servo, ignition timing, etc. for
-mum cranking conditions.

14-50FUEL SYSTEM- Idle Speed Control
SDeed adiustina screwI -Throttle valve
Lw-3O(-22) 0132) 30(86! 601140) 9ofl94)Coolant temperature
“C (OF)6FUO641
E94
72--2--I
Q--.-.-z
3201.000 --4-\-\
5P9.o%IIIaI L-2O(-41 Of3214Of104)801176)Coolant temperature
“C VF)6FU028E
-201-4) Of3214OI104180(176(2) When the engine coolant temperature is low, the fast idle
air valve together with the idle speed control
servoperated to supply an adequate volume of bypass
,.raccording to the engine coolant temperature.
Feedback Control at
Idle(1) Basic target idle speed
The basic target idle’ speed is preset as a map value
optimized according to the engine coolant temperature.
This speed is maintained to ensure stabilized idle speed.
(2) Idle speed while the air conditioner is being operated
When the engine coolant temperature is high with the air
conditioner switch in the ON position, the idle speed is set
higher than the basic idle speed.
,
ICoolant temperature “C VF)6FUO28:Position Control
When the steering wheel is turned or the air
conditioner switch is operated while idling, theachieve the target position, thus controlling the
engine load changes and consequently the idlebypass air volume and suppressing engine speed
changes. The engine control unit also activates the
speed changes sharply. Therefore, immediately
after detection of such a load signal, the engine
control unit activates the idle speed control servo toidle speed control servo to achieve the optimum
target position while cranking, driving and decelerat-
ing, according to the operating conditions.
Power steering oil
pressure switchIInhibitor
switch
IDash pot
concjition“D”
xl
rangeposition-
UP W-U
IAlPower
steeringposition-
UP.4~i~hnditioner
IIdle speed
control servor”--““IiiI
I
c
IEngine
I
I
1wuosu
-

FUEL SYSTEM -Idle Speed Control14-51
_ 0 (32)80 (175)Coolant temperature “C (“F)6FUO2653
ATarget position during operation
of the power steering systemIDLE CONTROL SERVO POSITION CONTROL WHEN THE
ENGINE IS IDLING
(1) Basic position
The basic position is preset as a map value Optimized
according to the engine coolant temperature. The idle
speed control servo is activated to conform to this position,
thereby maintaining the optimum idle speed.
This basic position of the idle control servo
diiectlycorresponds to the basic idle speed described earlier.
1II
0(32)
80(176)Coolant temperature
“C VW6FUO291Servo position
during operation of
the air conditioner
0(32)
80(176)Coolant temperature “C (“F)6FUO757
1L)760 (30)Barometric pressure mmHg
(in.Hg)BFUlOlC(2) Servo position during shift to “D” range
For models equipped with the automatic
transaxle.when
the position of the shift lever is anywhere other than the
“P” or “N” range, the servo position is increased in
proportion to the load of the torque-converter.
(3) Idle control servo position during operation of the power
steering system
When the power steering oil pressure switch is turned on
because the steering wheel is being turned while
thevehicle is stationary, the servo position is changed to
correspond to the increased power steering pump load.
(4) Servo position while the air conditioner is being operated
When the air conditioner switch is turned on, the servo
position is changed to correspond to the increased air
conditioner load.
(5) High altitude compensation
A correction is performed by increasing the opening of the
idle speed control servo to allow increasing bypass air flow
in order to compensate for the loss of intake air volume
(asmeasured by weight) caused by a reduction in intake air
density due to a drop in barometric pressure at increased
altitude.
(6) “Training” function
A “training” function that enters a value based upon the
engine rpm and the target rpm into the memon/,
andcorrects the servo position according to this value, is
provided in order to obtain an even higher degree of
precision of position control.

. -.-REAR SUSPENSION
- Double Wishbone SuspensionDOUBLE WISHBONE SUSPENSION
CONSTRUCTION AND OPERATION17-11
R17GAAP1. Suspension
crossmember2. Upper arm
3. Lower arm
4.Axle housing5.Trailing arm
6.Middle jointLeft
Right
12AOO58
1.The suspension consists of a pair of lateral arms
centerline of the upper and lower arm ball joints
(upper arm (2) and lower arm
(3)) mounted on
as a steering axis.
the suspension crossmember
(1) and trailing
The trailing arm and axle housing are rigidly
arm (5). The lateral arms and axle housing (4) areconnected.
connected by the ball joints. The axle housing,The suspension geometry is basically deter-
that is, the rear wheel can rotate about the
mined by the layout of these components.
2. The trailing arm also has a middle joint provided closer to
the suspension crossmember. As it is connected by pin
(7)that runs through it vertically, parts (A) and
(B) can rotate
relative to the pin. The insertion of rubber body
(8) creates a
spring constant in the direction of rotation.

17-12REAR SUSPENSION - Double Wishbone Suspension
12AWY
lZAOOS!
When cornering. I.to the right
I Toe-inToe angle
ReboundBump-
PositiveCamber(to body)
- Camber to ground: 0
Bump
Semi-trailing typeThis middle joint is located exterior to straight line
(p’connecting the trailing arm end mounted on the crossmet
ber side with the axle housing (king pin).
Because of this arrangement, the momentary center
P(intersection of front member centerline
(0,) of the trailing
arm and line
(02) interconnecting the middle points of the
lateral arm mounting points) is positioned rearward of the
wheel center.
3. When the wheel is subjected to an external force acting
towards the rear or to a braking reaction, the force FR acts
as a moment about momentary center
P, causing the tire to
steer in the toe-in direction, thereby securing directional
stability of the vehicle.
While the vehicle is cornering, side force Fc acts on the
outer wheel from the inside and side force Fc’ acts on the
inner wheel from the outside. These forces work
moments about momentary centers
P and P’, respective,,
to cause the outer wheel to be steered toward toe-in and
the inner wheel toward toe-out: As a result, both wheels
are steered in the same direction as the cornering direction
of the vehicle. This results in under-steering to improve
cornering performance and stability.
4.The change in toe angle and camber to ground is kept small
for bumps or rebounds as shown at the left and this
contributes to steering stability while cornering.

-
REAR SUSPENSION -Double Wishbone Suspension17-13
Member supponbushingI
12AOO5
Upper arm
Link diagram of ordinarydouble wishbone suspension system
5. The suspension crossmember is mounted with the mem-
ber support bushing on the body. The input from the wheel
is first damped by the trailing arm and the bushings of the
lateral arms. It is then further damped by the member
support bushing. This dual anti-vibration construction
provides low vibration and low noise.
In addition, mounting of the differential carrier on this
crossmember decreases the natural frequency of the
crossmember, further damping vibrations.
The lower natural frequency of the crossmember allows
harder adjustment of the support bushing so that the
tendency toward oversteering of the suspension due to
side force, occurring during cornering can be reduced. This,
combined with understeering tendency by middle joint
.displacement described in (3) above, results in totally slight
understeering tendency.
Why this new rear suspension system is classified as a double
wishbone suspension
The new rear suspension is represented below by the diagram
as an aid to understanding its construction.
F-7-,12AOO33!A/ \
12AOO37Point A can rotate about rotary axis B-C and point
Dcan rotate about rotary axis E-C. The triangles ABC
and DEC can rotate like wishbone suspension
arms.When this is compared to an ordinary double
wishbone type suspension, it may be regarded asone with forward points
C, and C2 of the upper and
lower arms located at the same point. Thus, this
new rear suspension system is considered as a
double wishbone suspension system.

POWER STEERING- General Information19-3
SPEClFlCATlONSItems
Steering wheel O.D.
mm (in.)Steering wheel maximum turns
Shaft and joint type
Steering angleInner wheel
Outer wheel
Tilt strokemm
(in.1Steering gear type
Rack strokemm (in.)Oil pump type
Oil pump displacement
cm3/rev. (cu.in./rev.)Specifications
372
(14.6)
2.7
Collapsible, cross joints (two joints used)
35”OO’ + 2”
29”20’
30
(1.2)
Rack and pinion
138
(5.41
Vane type9.6
l.59)

19-6POWER STEERING- Pinion and Valve Assembly Construction
PINION AND VALVE ASSEMBLY
CONSTRUCTION
RISKAMThe pinion and valve assembly is composed of the
input shaft, torsion bar, pinion gear and rotary valve.torsion bar, the pinion gear is provided with a
stopper. Note that this stopper also functions to
The input shaft is hollow and incorporates the
fa&tate the transmission 6i the turning effort of
torsion bar within it; the upper end is secured bythe steering wheel directly to the pinion gear by
a pin to the torsion bar, and the lower end is heldthe input shaft in the event of a malfunction of
by the bushing within the pinion gear.the hydraulic system (such as breakage of the oil
The torsion bar is coupled to the pinion gear bypump’s V-belt, fluid leakage, etc.).
the serrated part at the lower end.
lThe rotary valve is attached to the pinion gear by
In order to prevent excessive torsion of thea dowel pin.
Torsion barPm13AOO76Dowel
Section A-A
Input shaft\Torsion barpin’Stopper
/Rotary valvePinion gear1310202

:POWER STEERING
- Pinion and Valve Assembly Construction19-7 ’fOPERATION OF THE PINION AND VALVE
fi %EMBLYdulation of the hydraulic pressure applied to the
power cylinder is performed by the input shaft and
the rotary valve.
The concave and convex parts at the input shaft
surface and the rotary valve inner surface, due to
the rotational difference, function to either constrict
or expand the fluid passageway (by varying the
aperture surface area of the fluid passageway), and,
as a result, thereby regulating the hydraulic pressure
of the hydraulic circuit from the oil pump to the
cylinder tube left chamber or right chamber and
from the cylinder tube right chamber or left chamber
to the oil reservoir.
WHEN THE STEERING WHEEL IS TURNED TOTHE
RIGHTWhen the steering wheel is turned to the right, the
Port b\
Port a\Pond’
Ltorsion bar is. as shown in the illustration, caused to
torque in the direction of turning to the right, with
the result that the input shaft rotates by the
corresponding amount to the right, and a rotational
difference between the input shaft and rotary valve
develops. The concave and convex parts of the
input shaft and rotary valve cause oil passageways
R’ and L to become constricted, with the result that,
for the fluid sent from the oil pump, the flow of fluid
is stopped from port “a” to port “d” and port “c”.
When this happens, the fluid flows from the oil
pump to sleeve “a”,port “a”, port “b” and sleeve
‘lb”, and is sent to the cylinder tube right chamber,
thus causing the generation of a force to move the
rack in the leftward direction, thereby assisting the
steering effort of the steering wheel. At the same
time, the cylinder tube left chamber fluid flows
through sleeve “c”, port “c”, port “d” and chamber
“A”, and is returned to the oil reservoir.
Port c
Oil pumpOil ryetvoir
From the leftcylinder tubeChamber “A”
Torsion bar Port
b
//II YPO< aPond
4Cylinder tube
left chamberCylinder tube
right chamber