1999 HONDA CR-V Wheel

Transfer Assembly
Removal
@ Make sure the lifts, iacks, and safety
stands are placed properly (see section 11.
1. Raise the front of the vehicle, and make sure it is
supported securely.
2. Set the parking brake, and block both rear wheels
securelv.
3 Drain the automatic transmission fluid (ATF).
Reinstall the drain plug with a new sealing washer'
DRAIN PLUG'18 x'1.5 rnm49 N.m 15.0 kgf.m, 36 lbl.ftl
4. Remove the guard bar and the splash shield.
GUARD 8AR
14-165
5.Disconnect the primary heated oxygen sensor
{Primary HO2S) connector.
Remove exhaust pipe A.
SELF-LOCKINGNUTBeplace.
7.
SEI-F.LOCKINGNUTReplace.
NUTReplace
Remove the shift cable cover.
Remove the snap pin and control pin, then separate
the shift cable from the control lever. Do not bend
the shift cable excessively.
(cont'd)
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Transmission
Removal
@
2.
'1.
Make sure lifts. iacks, and safety stands aro placed
properly, and hoist brackets are attached to the col-
rest position on the engine lsee section 11.
Apply th€ parking brake and block the r€ar wheels,
so vehicls will noi roll off the stands and fall on you
while working under it.
NOTE: Use fender covers to avoid damaging painted
surfaces.
Disconnect the negative terminal, then disconnect
the positive terminal from the battery.
Remove the intake air duct and the air cleaner hous-
ing assembly,
Remove the starter cables. Remove the harness
clamp from the clamp bracket.
5.
STARTERCABLES
Remove the transmission ground cable terminal
and the radiator hose clamp lrom the transmission
hanger.
Disconnect the lock-up control solenoid valve con-
nector, then remove the harness clamp from the
clamp bracket.HARNESS CLAMP
RADIATOR HOSECLAMP
CONTROLSOLENOID VALVECONNECTOR
CLAMP
6. Disconnect the vehicle speed sensor (VSS), the coun-
tershaft speed sensor, and the A/T gear position
switch connectors.
A/T GEAR POSITIONSWITCH CONNECTOR
VEHICLE SPEEDSENSOR |VSS'
CONNECTORBfiACKET
SPEED SENSORCONNECTOR
7. Remove the transmission housing mounting bolts.
MOUNTING BOLTS
(cont'd)
14-169
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26. Connect the vehicle speed sensor (VSS). the coun-
tershaft speed sensor. and the A,/T gear position
switch connectors,
VEHICLE SPEEO
SPEED SENSOACO'{NECTOR
Connect the lock-up control solenoid valve connec-
tor, then install the harness clamp on the clamp
bracket.
HARNESS CI-AMP
27.
RADIATOR HOSECLAMP
TRANSMISSIONGROUND CAB1ITERMINAL
LOCK-UP OONTROLSOLENOID VALVECONNECTOR
6x1.0mm12 N'm (1.2 kgi.m,8.? tbtftl
28.
29.
Instail the transmission ground cable terminal on
the transmission hanger, and install the radiator
hose clamp on the transmission hanger,
Connect the starter cables to the starter, and install
the harness clamD on the clamD bracket. Make sure
the crimped side of the starter cable ring terminal is
facing out.
STARTEBCABLE
STARTER CAAtf,
Install the air cleaner housing assembly and the
intake air duct.
Refill the transmission with ATF (see page 14-161).
Connect the battery positive terminal and negative
terminal.
Set the parking brake, Start the engine, and shift the
transmission through all gears three times.
Check the shift cable adjustment (see page 14-271]-.
Check the tront wheel alignment and adjust it if
needed (see section 18).
Let the engine reach normal operating temperature
(the radiator fan comes on) with the transmission in
E or N position, then turn it off and check the ATF
level {see page 14-160).
Perform a road test (see page 14-157 and 14-158).
30.
31.
34.
CLAMP BRACKET
37.
14-263
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Description
Rear Differential
Outline
The Real-time 4WD-Dual Pump System model has a hydraulic clutch and a differential mechanism in the rear differential
assembly. Under normal conditions, the vehicle is driven by the front wheels. However, depending on to the driving force
of the front wheels and the road conditions. the system instantly transmits appropriate driving force to the rear wheels
without requiring the driver to switch between 2WD (tront wheel drive) and 4WD (four wheel drive). The switching mecha-
nism between 2WD and 4WD is integrated into the rear differential assembly to make the system light and compact.
ln addition, the dual-pump system switches off the rear-wheel-drive force when braking in a forward gear. This allows the
braking system to work properly on models equipped with an Anti-lock Braking System (ABS).
Construction
The rear differential assembly consists of the torque control differential case assembly and the rear differential carrier
assembly. The torque control differential case assembly consists of the differential clutch assembly, the companion
flange, and the oil pump body assembly. The rear differential carrier assembly consists of the differential mechanism. The
differential drive and driven gears are hypoid gears.
The oil pump body assembly consists of the front oil pump, the rear oil pump, the hydraulic control mechanism, and the
clutch piston. The clutch piston has a disc spring that constantly provides the differential clutch assembly with a preset
torque to Drevent abnormal sound.
The clutch guide in the differential clutch assembly is connected to the propeller shaft via the companion flange, and it
receives the driving force lrom the transfer assembly. The clutch guide rotates the clutch plate and the front oil pump in
the oil pump body.
The clutch hub in the differential clutch assembly has a clutch disc that is splined with the hypoid drive pinion gear. The
hypoid drive gear drives the rear oil pump.
The front and rear oil pumps are trochoidal pumps. The rear oil pump capacity is 2.5 percent larger that the front oil pump
to handle the rotation difference between the front and rear wheels caused by worn front tires and tight corner braking.
The oil pumps are designed so the fluid intake works as a fluid discharge when the oil pumps rotate in reverse. Genuine
Honda CVT fluid is used instead of differential fluid.
Operation
When there is a difference in rotation speed between the front wheels (clutch guide) and rear wheels (hypoid driven gear),
hydraulic pressure from the front and rear oil pumps engages the differential clutch, and drive force from the transler
assembly is applied to the rear wheels.
The hydraulic pressure control mechanism in the oil pump body selects 4WD mode when the vehicle is started abruptly,
or when accelerating in a forward or reverse gear (causing rotation difference between the front and rear wheels). or
when braking in reverse gear {when decelerating). lt switches to 2WD mode when the vehicle is driven at a constant speed
in forwar! or reverse gear (when there is no rotation difference between the front and rear wheels), or when braking in a
fo rwa rd gear (when decelerating).
To protect the system, the differential clutch assembly is lubricated by hydraulic pressure generated by the oil pumps in
both 4WD and 2WD modes. Also, the thermal switch relieves the hydraulic pressure on the clutch piston and cancels 4WD
mode if the temDerature of the differential fluid rises above normal.
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Description
Hydraulic Flow
Forward Start and Acceleration l4WD)During a forward start and forward acceleration, the dual pump system can engage four wheel drive.lf the front wheels spin faster than the rear wheels, the front oil pump spins faster than the rear oil pump. The front pump
draws fluid through check valve B and discharges it. Some of the discharged fluid is drawn in the by the rear oil pump.The remaining fluid will pass through check valve E into the clutch piston. There, hydraulic pressure is regulated by twoorifices.
The regulated hydraulic pressure at the clutch piston pushes the plates and discs of the clutch together to form a connec-tion. The engaged clutch then passes driving force from the transfer assembly to the rear wheels, producing 4WD.
oRrFtcEsFRONT OIL PUMPREAR OIL PUMP
Forward Driving at Constant Speed lzWD)When driving forward at a constant speed (cruising), the dual pump system functions in two wheel drive mode.The rotation speed of the front and rear wheels is the same, so the speed of the front and rear pumps is also the same.Fluid discharged by the front oil pump is drawn in by the rear oil pump and is circulated through the system. Becausethere is no pressure built up at the clutch piston, the clutch does not engage, and the vehicle remains in 2WD (front wheeldrive).
FRONT OIL PUMP
15-6
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Forward Deceleration l2WDl
During forward deceleration, the dual pump system functions in two wheel drive mode.
Because of braking characteristics, the speed of the rear wheels may exceed the speed ol the front wheels during deceler-
ation. lf so, the rear oil pump spins faster than the front oil pump.
Fluid discharged by the rear oil pump is simply drawn in again by the rear pump and recirculated. Because there is no
pressure built up at the clutch piston. the clutch piston does not engage, and the vehicle remains in 2WD (front wheel
drive).
Reverse Start and Acceleration (4WD)
During reverse start and reverse acceleration, the dual pump system can engage four wheel drive.
lf the front wheels spin faster than the rear wheels, the front oil pump spins faster than the rear oil pump. The front oil
pump draws in fluid through check valve A and discharges it. {Note that in reverse, the direction of the pumps is the oppo-
site of that during forward driving.)
Some of the fluid that is discharged by the front oil pump is drawn in by the rear oil pump. The remaining fluid passes
through check valve F into the cylinder of the clutch piston, where it is regulated by two orifices.
The regulated hydraulic pressure at the clutch piston may force the plates and discs of the clutch together to form a con-
nectlon. The engaged clutch passes driving force from the transfer assembly to the rear wheels, producing 4WD.
oRtFtcEsFRONT OIL PUMP
{cont'd)
15-7
REAR OIL PUMP
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Description
Hydraulic Flow (cont'dl
Reverse Driving at Constant Speed l2WD)when driving in reverse at a constant speed, the dual pump system functions in two wheel drive mode.The rotation speed of the front and rear wheels is the same, so the speed of the front and rear pumps is also the same,Fluid discharged by the front oil pump is drawn in by the rear oil pump and is circulated through the system. But, becausethe there is a difference in the capacity between the two pumps, fluid flows through check valve E, and then through ori-Iices. This fluid lubricates and cools the clutch assembly and bearings.ls this condition, only a low pressure is built up at the clutch piston. Therefore the clutch does not engage, and the vehicleremains in 2WD (front wheel drive).
Reverse Deceleration l/tWDl
During reverse deceleration, the dual pump system can engage four wheel drive.When decelerating in reverse direction, the speed of the rear wheels may exceed the speed of the front wheels (due toengine braking). In this condition, the rear oil pump draws fluid through check valves B and C. Fluid discharged from therear oil pump then flows through check valve E to the clutch piston. There, pressure is regulated by two orifices.The regulated hydraulic pressure at the clutch piston may force the plates and discs of the clutch together to form a con,nection. The engaged clutch passes driving force from the transfer assembly to the rear wheels, producing 4WD.
oRtFtcEsREAR OIL PUMP
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Thermal Switch Operation l2WD)
During 4WD operation, pressure-regulated fluid is in contact with the clutch piston and the thermal switch.
lf the temperature of the fluid in the differential goes too high, the thermal switch pushes open the relief valve R. This
causes the pressure in the clutch piston to drop, and 4WD mode is disengaged.
THERMAL SWITCHRELIEF VALVE
Reliet Valve Operation
When the fluid pressure goes higher than the relief valve spring force, check valve R opens. Pressure applied at the clutch
piston is held constant. This feature adds stability by preventing the rear wheel drive system from experiencing excessive
to rque.
RELIEF VALVE
15-9
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