1999 HONDA CR-V rear control

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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TOROUE CONTROL OIFFERENTIAL
REAR DIFFERENTIAL ASSEMBLY
OIL PUMP BODY
OIFFERENTIAL CLUTCHHYPOID DRIVEPINION GEAR
OIFFERENTIAL CARRIER
DIFFERENTIAL
HYPOID RING GEAR
DIFFERENTIAI- HOUSING
REAR OII- PUMP
ASSEMBLY
CLUTCH GUIDE
COMPANION FLANG€
CLUTCH HUB
CLUTCH PLATE
HYDRAULIC CONTROL SYSTEM
CLUTCH PISTON
CLUTCH DISC
REAR OIL PUMP
FRONT OIL PUMP
DISC SPRINGFRONT OIL PUMP
DIFFEREMT|AL CLUTCHASSEMBI-Y
THERMAL SWITCHRELIEF VALVEOIL STRAINER
15-5
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Real-time 4WD-Dual Pump System
Troubleshooting (Automatic Transmission/Manual Transmission)
Whon d6c6l6rating in a torward gear {2WD mode}
1. Block the front wheels, raise the left rear wheel. and
support it with a safety stand as shown.
Hold the tire and turn it counterclockwise continu-
ouslv for more than one rotation.
lf the rotation of the wheel does not gradually
feel heavy while rotating, the 2WD system when
decelerating in a forward gear is normal.
lf the rotation of the wheel gradually feels heavy,
there is a problem in the system. Check the dif-
ferential fluid, lf the fluid is normal, reDlace the
toroue control differential case kit.
WHEEL CHOCKS
15-12
When decelerating in reverse gear (4WD mod€)
1. Block the front wheels. raise the left rear wheel, and
suppo( it with a safety stand as shown.
Hold the tire and turn it clockwise continuouslv for
more than one rotation.
lf the rotation of the wheel gradually feels heaw.
the 4WD system when decelerating in reverse gear
is normal,
lf the rotation of the wheel does not gradually feel
heavy, there is a problem in the system. Check
the differential fluid. lf the fluid is normal.
reolace the torque control differential case kit,
WHEEL CHOCKS
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Oil SealsRear Differential Assembly
Replacement (cont'd)
3. Remove the oil seal from the toroue control differ-
ential case.
Install the oil seal squarely using the special tool.careful not to damage the lip of the oil seal.
15-20
BREATHER TUBE
DRAIT{ PLUG
Disassembly
1. Remove the breather tube, the drain plug and the oilfiller plug.
OIL FILI.IR PLUG
Raise the locknut tab from the groove of the clutchguide, making sure that the tab completelv clearsthe groove to prevent damaging the clutch guide.
L(rcKNUT, 24 mmReplace.
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Rear Differential Assembly
Reassembly (cont'dl
7. Install the clutch hub/plates/discs, then align the pro-
jection of the plates with the discs.
M, 30 mm
CLUTCH GUIDE
sHl
,/
.A-\,/r\-7
8.
9.
CLUTCH HUA/PLATES/Dtscs
Installthe clutch guide and the 30 mm shim.
Apply liquid gasket to the sealing surface of the
torque control differential case, and note these
rlems:
. Use liquid gasket (P/N 08718 - 0001).
. Remove any dirt or fluid from the sealing sur-
face.
. lf 20 minutes have passed after applying liquid
gasket, reapply it before you assemble the hous-
ings. Allow it to cure at least 30 minutes after
assembly before filling differential with fluid.
TOBOUE CONTROLDIFFERENNAL
--- Apply liquid gaskot
15-24
6x1.0mm12 N.m 11.2 tgf m,8.7lbt.ftl
10. lnstall the dowel pins and toroue control differential
case.
TOROUE CONTNOL
11. Install the companion flange, O-ring, back-up ring,
disc spring washer, and the locknut.
NOTE: Apply CW fluid to the O-ring.
,24mm
DISC SPRING WASHER,2a mm
lnstall in this direction.
@+-_alcr-upnwc
COMPANION FLAI{GE
/r-
K@#/
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Master Cylinder/Brake Booster
Removal/lnstallation
1, Disconnect the brake fluid level switch connectors.
2. Remove the reservoir cap from the master cylinder.
3. Remove the brake fluid from the master cvlinder
reservoir with a syringe.
4. Disconnect the brake lines from the master cylinder.
To prevent spills, cover the line joints with rags or
shop towels.
5. Remove the master cylinder mounting nuts and
wasners.
6. Remove the master cylinder from the brake booster.
CAUTION: Be careful not to bend or damage the
brake lines when removing the master cylinder.
Do not spill brake fluid on the vehicle; it may dam.
age the paint; it brake fluid does cont.ct the paint,
wash it oft immediately with water.
7. Disconnect the vacuum hose from the brake booster.
8. Remove the cotter pin and clevis pin from the clevis.
Do not disconnect the clevis by removing it from
the operating rod of the brake booster. lf the clevis
is loosened, adjust the pushrod length before
installing the brake booster (see page 19-15).
To Front Caliper (Without ABS)
\\
15 N.m {1.5 kgtm, vAcuuM HosE
r r rbf.ft) |
/ | BRAKE FLUTD LEvEL
/l /
swrrcHcoNNEcroRs
/ I I I COTTER PIN
I I / neotace
l,/-- ro Rear wheet cylinders / | I
h ./-''' /. I I IYli //*s (.S
I /r:
9. Remove the four booster mounting nuts.'10. Pull the brake booster forward until the clevis is
clear of the bulkhead.
11. Remove the brake booster from the enqine com-
panment.
12. Install the brake booster and master cylinder in the
reverse order of removal, and note these items:
. When connecting the brake lines, make sure that
there is no interference between the brake lines
and other parts.
. Be careful not to bend or damage the brake lines
when installing the master cylinder.
. lf replacing the master cylinder or brake booster,
check and adjust the pushrod clearance before
installing the master cylinder (see page 19-14).
Fill the master cylinder reservoir, and bleed the
brake system (see page 19-7).
After installation, check the brake pedal height and
brake pedal free play (see page 19-5), and adjust if
necessary.
13 N.m 11.3 kg{.m,I rbf.ft)
13.
14.
To Master Cylinder(Without ABS)To Modulator Unit(with ABs)@-\
\
^ To Front Caliper
9i\.
-#qCLEVIS PIN
):-,/
PROPORTIONING CONTROL VALVE
MASTER CYLINDER
15 N.m (1.5 kgf.m, 11 lbl.ftl
BRAXE BOOSTER
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Component Locations
NOTE: The illustrations show the '97 - 98 models. The '99 - 00 models are similar.
ABS CONTROL UNITRIGHT-REAR WHEEL SENSOR
UNDER.HOOD ABSFUSE/RELAY BOX
RIGHT.FRONT WHEELSENSOR CONNECTOR
RIGHT-FRONTWHEEL SENSORRIGHT-REAB WHEELSENSOR CONNECTOR
MODULATOR UNIT
LEFT.FRONT WHEEL SENSOB
UNDER.DASH FUSE,/RELAY 8OX
UNDER.HOOO FUSE/RELAY AOX
IGl I(, AI FUSE
ABS +B 120 Al FUSEPUMP MOTOR ('II AI FUSE
HOBN/STOP I15 AI FUSE
UNDER.HOOD ABS FUSE/RELAY BOX
LEFT.FRONT WHEELSENSOE CONNECTOR
GAUGE ASSEMBLY
ABS INDICATOR
UNDER-DASH FUSE/NELAY BOX
METER {7.5 AI FUSE
MOTOR RELAY
19-27
SERVICE CHECK CONNECTOR {2PI
D!
trtrtr
[r D!
ABS {7.5 AI FUSEMTR CHECK 17.5 AI FUSE
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Anti-lock Brake System (ABS)
Features/Construction
When the brake pedal is pressed during driving, the wheels can lock before the vehicle comes to a stop. In such an event,
the maneuverability of the vehicle is reduced if the front wheels are locked, and the stability of the vehicle is reduced if the
rear wheels are locked, creating an extremely unstable condition. The ABS precisely controls the slip rate of the wheels to
ensure maximum grip force from the tires, and it thereby ensures maneuverbility and stability of the vehicle.
The ABS calculates the slip rate of the wheels based on the vehicle speed and the wheel speed, then it controls the brake
fluid pressure to attain the target slip rate.
Grip Force of Tire and Road Surlace
COEFFICIENT OFFRICTION
TARGET SLIP RATE
RADIALOIRECTIONOF THEROTATIONALDIRECTION
SLIP RATE
19-24
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