1998 HONDA CR-V 5 speed

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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Troubleshooting
General Troubleshootin g
Check the following before you begin:
. Has the suspension been modified in a way that would affect steering?
. Are tire sizes, tire variety and air pressure correct?
. ls the steering wheel original equipment or equivalent?
. ls the power steering pump belt properly adjusted?
. ls steering fluid reservoir filled to proper level?
. ls the engine idle speed correct and steady?
Hard Steering (Check the power assist, see page 17-12. lf the force is over 29 N (3.0 kgl 6.6 lbfl, proceed with this troubleshooting.i
Abnormalthiidpressure (Iluidpressure is toohigh)
Relief pressuretoo low
Faulty valve body unit
Abnormal
Check the teed and return circuit lines and hosebetween the gearbox and pump for clogging anddeformation.
Normal line and hose
Check the pump fluid pressure(see page 17-16 or 17-17).Measure steady state lluid pres-
sure at idle with the pressure con-trol valve and the shut-off valve (it
so equipped) fully open.The fluid pressure should be 1,500kPa (15 kgf/cm,,213 psi)or less.
Normal
Check the flow control valve (see page 17 26).. Check the valv€ lor smooth movement in the hous-ing.. Check the relief valve for leaks.
Check the pump fluid pressure(see page 17-16 or l7-17).Measure pump relief pressure atidle with the pressure controlvalve and the shut'off valve lil soequipped) fully closed.The fluid pressure should be 6,9007,800 kPa (70 - 80 kgflcm,, 1,000- 1,140 psi).
Normal relief pressure
17-4
Go to page 17 5Faulty pump assemblyFaulty flow control valve
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Troubleshooting
General Troubleshooting (cont'dl
Assist (excessively light steering) athigh speed.
Shock or vibration when wheel isturned to full lock.
Steering wheel will not returnsmoothly.
lf the problem is not corrected byadjusting the rack guide, adjustthe front wheel alignment (see
section 18).
Check the rack guide for proper
adjustment (see page 17-15).
Check the rack guide for properadjustment (see page 17'15).
Adjust the rack guide.
Rack guide is adiusted properly.
lf the problem is not corrected byadjusting the rack guide, replacethe gearbox.Check the belt for slippage andadjust as necessary (see page 17-14).
A and B cylinder lines are normal, check wheel alignment (see
section 18).
Wheel alignment is abnormal,adjust as needed.
Wheel alignment is normal.Check the steering wheel opera-tion and power assist check (seepage 17-121.
lf the measurements are out ofspecifacations, adjust the rackguade.
lf the problem is not corrected byadjusting the rack guide, replacethe gearbox,
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Uneven or rough steering.Ad,ust the rack gu ide (see page 17- 15).
ll the problem is not corrected byadjusting the rack guide, replacethe gearbox.
Adjust the belttension. Replace thebelt, if necessary (see page 17-14).Belt slipping on pulley.
lf the engine stalls when thewheel is turned while the vehicleis stopped or moving at lowspeed, adjust the idle speed (seesection 111.
ldle speed low or erratic.
Check power steering lluid level. lfthe level is excessively low checkfor leaks in the system. Add fluidto the specified level.
Air in reservoir, or check powersteering tluid level.
lf fluid level is OK, check O-ringsand seals on both ends of thepump inlet hose, and the P/Spump housing mating surlacesand drive shaft oil seal for suction leaks. Check the reservoir forcracks, Replace parts as neces-
Pump belt slipping on pulley(pump stops momentarily).Adjust the belt tension (see page17-14) or replace belt.
Check if pump pressure is normaland the gauge needle travel is 500kPa (5 kgl/cm,, 71 psi) or less.Check the flow control valve if theneedle travel exceeds 500 kPa (5kgflcm', 71 psi). lI the flow controlvalve is normal, replace the pumpas an assembly,
Install the power steering pres-sure gauge, Close the pressurecontrol valve and shut off valve (if
so equipped) fully and measurethe pump pressure (see page 17-16ot 17 17).
Steering wheel kicks backduring wide turns.
7-7
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Master Cylinder
I nspection/Disassembly
CAUTION: Do not spill brake fluid onthe vehicle; it may
damsge the paint; il brake fluid does contact th6 paint.
wash it off immodiately with water.
NOTE:
. Before reassembling, check that all parts are free of
dust and other foreign particles.
. Do not try to disassemble the master cylinder assem-
bly. Replace the master cylinder assembly with a new
pan it necessary,
. Make sure no dirt or other foreign matter is allowed
to contaminate the brake fluid.
RESERVOIR SEALCheck for damaoe anddeterioration,
RESERVOIRCheck for damage.
ROD SEALCheck for damageand deterioration.
-€-1SILICONE GREASE
MASTER CYLINOERCheck bore for wear, rust and damage.
19-14
Pushrod Clearance Adjustment
NOTE: Master cylinder pushrod-to-piston clearance must
be checked and adjustments made, if necessary. before
installing the master cylinder.
1. Set the special tool on the master cylinder body;
push in the center shaft until the top ot it contacts
the end of the secondary piston by turning the ad-justing nut.
PUSHROD ADJUSTMENT GAUGE07JAG - SD{o100
SECONDARY
MASTER CYLINDER
ADJUSTING NUT
Without disturbing the center shaft's position, in-
stallthe special tool upside down on the booster.
Install the master cylinder nuts, and tighten them to
the sDecified toroue.
Connect the booster iniine with a vacuum gauge 0 -
101 kPa (0 - 760 mmHg, 30 in Hg) to the booster's
engine vacuum supply, and maintain an engine
speed that will deliver 66 kPa (500 mmH9, 20 in Hg)
vacuum.
With a feeler gauge, measure the clearance between
the gauge body and the adiusting nut as shown.
Clearanco: 0 - 0.4 mm (0 - 0.02 inl
VACUUM GAUGElCommo.cidly 6vailablcl0 - 101 kPtl0 - 760 mm Hg, 30 in Hgl
MASTER CYLINDER NUT15 N.m 11.5 kgt m, 11 lbt.ftl
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