1990 MITSUBISHI ECLIPSE oil

REAR AXLE- Viscous Coupling Type Limited Slip Differential3-a
DIFFERENTIALROlEAM
The differential uses lower torque bearings and
lower torque oil seals to improve power perform-
ante and fuel consumption.
For faster differential cooling and higher reliability
during high speed operation, a differential carrier
with cooling fins has been adopted.For better serviceability, spacers for adjustment of
final drive gear backlash have been inserted
be-tween the side bearing outer race and gear carrier.
A speed difference responsive type viscous
cou-
pling type limited slip differential which provides
outstandingperformance during operationon a
Side gearPinion gearDifferential coverQ./\Side bearing spaceifferential case
VISCOUS COUPLING TYPE LIMITED SLIP DIFFERENTIALRWEBAAWhile the conventional mechanical type limited slip
differential uses a cam (differential pinion shaft) and
disc equipment
compo.sed of a friction plate, disc
and spring seat in limiting the differential, theviscous coupling type limited slip differential limits
the differential by use of a viscous coupling equip-
ment consisting of outer and inner plates and
silicone oil.
Front wheel
Center differential
’ (viscous coupling)Rear wheel
Limited slip differential
assembly
Front differential, I
TDifferential
Differential limiting section
(viscous coupling)11KmI66
L.-

3-6REAR AXLE - Viscous Coupling Type Limited Slip Differential
Is
Side gear (L.H.)
Side gear (R.H.)1Differential case B
Pinion shaft
Thrust
washer
Viscous cokpling
3r
Side gear U3.H.)Differential case
B
, ,,Differential cover
I
‘Gear cagierPir
,Drive pinionfront bearing
Driv& pinionDrive gear
Bearing caprear bearing
ICokpanion flangellAo337
Normal operating range
Hump region
Difference in rotating speed between
right and left wheels (rpm)
RemarkslA hump occurs when there is a large differencein rotatinwheels..!speed between the right and leftlnce the large difference causes
violent shearing of the silicone oil in the
viscous couplin7.by the plates, the oil tempera-
ture rises (the SI Icone 011 expands), and the
torque abruptly rises. If the hump occurs, the
inner and outer plates enter a directly coupled(differential locked) state.llAOO5r
FUNCTIONS AND FEATURES(1) The viscous coupling type limited-slip differential
is functionally the same as
the conventional
mechanical type which reduces slipping of the
rear wheels for better performance when travel-
ing on a rough road or when getting out of a
snowy or muddy surface.
(2) The viscous coupling type limited slip differential
responds to a difference in rotating speed and
has outstanding characteristics for use in an
on-road
4WD vehicle, as it has no difference in
characteristics in the normal operating range
between when power is ON and when it is OFF,
and provides better straight ahead stability and
running performance.
(3) When a single wheel is slipping, a hump could
cause the differential to approach a locked state.
Provision is therefore made to provide a better
ability to get out even in cases of one in a million
such as a stuck state.

REAR AXLE -Viscous Coupling Type Limited Slip Differential3-7CONSTRUCTION
Rear drive
/shaft (L.H.)Serration coupled
ElDrive pinion
Rear driveshaft (R.H.1
11Po070The viscous coupling type limited differential is a
“shaft-shaft” type consisting of the right and left
rear drive shafts and viscous coupling directly
coupled. The viscous coupling is a unit filled with
silicone oil and consists of the outer plates @
coupled with the case @ , the inner plates @
coupled with the viscous coupling hub
(j) , and the
spacer rings @ arranged alternately to hold one
plate and angther with only a small spacing in
between. The X-rings @ are provided to prevententry of the differential oil into the viscous coupling.
The rear drive shaft
(L.H.) is serration coupled with
the viscous coupling case @ and coupled
,via the
case with the side gear
(L.H.) @which is in a single
body with the-viscous coupling case.
The rear drive shaft
(R.H.) is serration coupled with
the side gear
(R.H.) and its end serration coupled
with the viscous coupling hub
0) .
The viscous coupling must not be disassembled.

w
3-8REAR AXLE - Viscous Coupling Type Limited Slip Differential
OPERATIONDrive force smaller
I(Slipping side)Drive force larger(Grippina side)
Rear drive shaft
(L.H.1 (Left wheel)
resistance smaller)Rear drive shaft
(R.H.1 (Right wheel)
11 PO071If a difference in rotating speed occurs between the
right and left wheels, the viscous coupling case @
and viscous coupling hub @ relatively rotate with
the same difference in rotating speed as the rear
drive shafts. As a result a differential limiting torque
is generated by the shear resistance of silicone oil
and helps suppress the differential (slipping).For example, assume that the right wheel rotates at
20 rpm due to the road surface resistance, whereas
the left wheel rotates at 30 rpm. The difference in
rotating speed between the right and left wheels is
10 rpm. Since the viscous coupling is provided
between the right and left wheels, a differential
limiting torque compensating for the difference of
10 rpm in rotating speed is transmitted from the left
wheel to the right one.
Therefore, a larger drive force is transmitted to the
right wheel rotating at the lower speed.

-. ..- ,..__ _. I-., . . . . -. . “-Ix.. ...~‘,.;;&;,-*~;
CLUTCH- Clutch Control6-3
-
Inter-lock switchINTER-LOCK SWITCH
The inter-lock switch is a switch provided in order to prevent
sudden movement of the vehicle when the engine is star-ted.
BTAFTER YCTER
If the Clutch Pedal is Not Depressed:
Because the inter-lock switch is switched ON when
STABT
position, electricity flows from the cloil of the starter
relay, through the inter-lock switch, to ground. As a
?sult, the contacts of the starter relay separate,
vitching it OFF, and the starter motor is therefore
not activated.

IGNITION SYSTEMELECTRICAL - Engine Electrical8-25
I
Sensors
Engine control unitlgnltlon switch
Battery
11 IPower transfstor
hhP 1
Ilgnltion coil
C To tachometerTerminal for engine
speed detectton
6ELOO45The ignition system is a two-coil ignition system that
supplies sufficient energy for ignition up to high
speeds. This engine does not have a distributor
since the engine control unit directly activates the
power transistor for ignition timing control.
The functions and controls of the engine control unit
and various sensors that control the ignition timing
are described in the next chapter, IGNITION CON-
TROL SYSTEM.
This ignition system has two power transistors and
two ignition coils. Power transistor “A” controls the
primary current of ignition coil “A” to activate thespark plugs of the
No.1 and No.4 cylinders.
Similarly, power transistor
“B” controls ignition coil
“B” which activates the spark plugs of the
No.2 and
No.3 cylinders. In this way, spark plugs of two
cylinders are activated but actual ignition takes placeonly in the single cylinder that is on its compression
stroke, because the other is on its exhaust stroke at
that time.
Power transistors “A” and “B” are activated by
signals from the engine control unit, that controls
which cylinder is fired at what time.

8-26ELECTRICAL - Engine Electrical
No.:
4Signal unit for
, tachometer
71
x
No. 3
6EL0025
Capa &orCylinderNo. mark
6EL0057
To No. 1spark plug
To No. 4
spark plug
To No. 3spark plug
To No. 2spark plug
6EL005t
OC,IB, G
OC, IB, G IB, OC:IGNITION COIL
Two compact ignition coils of a molded type featuring
outstanding ignition performance are used.
Being a two-coil type, the ignition coil has a unit to supply
signals for the tachometer.
Specifications
itemsSpecificationsPrimary coil resistance
$20.86 at 20°C (68°F)
Secondary coil resistance
kR12.1 at 20°C (68°F)POWER TRANSISTOR
The power transistor is driven by a signal from the engine
control unit and turns the priman/ current of the ignition coil on
and off.
Terminal symbol
External connection
G
IB,
I&
Ground
Engine control unitEngine control unit
OGoc2Ignition coil terminal “2”
Ignition coil terminal “1”
SPARK PLUG
IEngineTypeGapI-
Non-turboBPR6ES-11WZOEPR-11RN9YC4
1.0-1.1 mm(.?39-.043 in.)I
0.7-0.8 mm(.OZB-.031 in.)A

-----. _-- ___ELECTRICAL
- Engine Electrical8-27IGNITION TIMING CONTROL SYSTEM
Air flow sensor
Engtne control unit
Intake air temp. sensor
Barometric pressure sensor
Engine coolant temp. sensorIdle position switch
:+
Top dead center sensor
Crank angle sensorVehicle speed sensor
;+Ignition switch “ST” terminal
Detonation sensor for
turbo engine only
Battev
4 Power= tranststor “B”P Ignition coil
109
_
I
1
12a”- To tachometer
Terminal for engine speed detection
Terminal for ignition,timing
and idle speed adjustment
6FUoE.45The ignition control system uses the engine control
consideration the operating conditions of the
en-unit, that judges which cylinder is to be fired at what
gine. The functions and controls of the engine
time based on the signals coming from variouscontrol unit are described in the following page.
sensors. The engine control unit activates the
The constructions and functions of the various
power transistors so that ignition occurs, taking into
sensors are described in GROUP 14.