1998 JAGUAR X308 steering wheel

6. NO
TE: The suitable funnel should have the a capacity of 4
litres and O-ring seal
• NOTE: The suitable funnel must be tightly sealed to the
power steering fluid reservoi r to avoid fluid leakage.
Install a suitable funnel onto the power steering fluid
reservoir.
7. WARNING: Do not work on or under a vehicle supported
only by a jack. Always support the vehicle on safety stands.
Raise and support the vehicle with the wheels just clear of the
ground.
8. CAUTI
ONS:
Steps 8 and 9 must be carried out within 2 - 3 seconds of
each other. Failure to follow this instruction may result in damage
to the power steering system.
Be prepared to collect escaping fluids.
Using the suitable funnel, top up the power steering system
with the specified fluid. Make su re the fluid level is maintained
at two thirds full in the funnel.
9. CAUTI
ONS:
Be prepared to collect escaping fluids.

The steering rack assembly :
Is mounted on the
rear face of the
front suspension crossbeam by two forg ed mounting brackets with resilient
bushes. The bushes are handed (pinion side and non-pinion side) and are orientated according to the vehicle range
application.
Convert s
the rotary motion of the steering wheel, via the steering gear pinion, to the lateral motion of the rack.
F
e
atures a variable ratio steering
rack with integral hydraulic po wer steering cylinder and piston.
Has a hydrauli
c control valve with Servotronic co
ntrol and positive center feel torsion bar.
The basic steering rack assembly is not serviceable. The following components are serviceable items:
Transfer pipework
.
Servotronic valve. Cent
ralizing cap.

O
u
ter ball joint.
Rac
k
gaiter.
Clips and

fittings.
Steering Rack Components
It e
m
Par
t
Number
De
scr
iption
1—Front
su
spension crossbeam
2—Steeri
ng rack housi
ng
3—Hydraulic

control valve housing
4—Moun
ting bracke
t
5—Gait
er

6—Tie
rod

7—O
u
ter ball joint

Steering R
a
ck Assembly

P a
rts List
The variable ratio rack:
Incorporates teeth
of varying pitch and angle of contact, giving a variable pi
tch circle diameter which is a minimum
at the center of the rack and a maximum at the ends.
R e
duces excessive response to on-center stee
ring inputs during motorway driving.
Causes the steering action to become pro
gressively more
direct as the stee ring wheel is turned from the center
position.
Allows a low n u
mber of turns of the
steering wheel from lock to lock.
Ite
m
Par
t
Number
De
scr
iption
1—Steeri
ng rack
2—Tooth contact an
gle at
center of rack
3—Tooth c o
ntact angle
at ends of rack

Variable Ratio Steering Rack

P
arts List
The positive center-feel torsion bar improves the straight ahead feel of the steering in the region where very small amounts
of hydraulic pressure, and hence re action pressure, are generated.
The torsion bar assembly forms part of the hydraulic control valve assembly , and includes an axially pre-loaded metal
bellows spring, which is arranged co-axially with the torsion bar. The torsion bar is positively connected between the end
piece and the input shaft. One end of the bellows spring is attached to the input shaft, while the other end is attached to a
centering device. The centering device has two prism-shaped recesses with ca ged, guided, ball bearings arranged between
the recesses, and determines the zero-torsion position of the bellows spring.
On turning the steering wheel from the straight ahead position, the spring fo rces of the torsion bar assembly must be
overcome. Initially, the bellows spring produces substantial additional torsional resistance. However, after an angular
movement of approximately 0.2 degrees the torsional rigidity decreases and becomes similar to a conventional torsion bar.
It
em
Par
t Number
De
scription
1—End piece
2—Torsio

n bar
3—Caged ball bearing

s
4—Centering device
5—Bel

lows spring
6—In

put shaft


Positive Center-Feel Torsion Bar

Torsio
n Bar Components

m
ember. The quick-fit connector O-rings are not serviceable.
Special tool JD 182 is required to disconnect the quick-fit connector.
Hydraulic System


P
arts List
Hydraulic System

Op
erating Principle
The rot
ary motion of the steering wheel is converted, via the st
eering rack pinion, to the lateral motion of the rack. Steering
assistance is provided by pressurized fluid being directed against a piston operating within the rack cylinder. Rack
movement is achieved by diffe rential pressures being applied on either si de of the rack piston, caused by unequal
restrictions within the hydraulic control valve.
The main components of the hydraulic control valve are the rota ry distributor, control sleeve and hydraulic reaction piston.
It
em
Par
t Number
De
scription
1—F

luid reservoir
2—Pum

p
3—Pressure and fl

ow limiting valve
4—Supply line
5—R

eturn line
6—Steeri

ng rack
7—Pin

ion
8—O

perating cylinder and piston
9—Hydrau

lic control valve
10—Hydraulic reaction

piston
11—Control

sleeve
12—R

otary distributor
13—F

luid cooler


A
quick-fit connector with double O-ring se
als is incorporated in the return line and is clipped to the right-hand chassis side

The rotary distri
butor and control sleeve turn relative to ea
ch other, forming the unequal restrictions which create the
differential pressures to operat e the rack piston; the displacement of the di stributor and sleeve being controlled by the
elastic deformation of a torsion bar which is concentric with the pinion and valve. Refer to Positive Center-Feel Torsion Bar
in this sub-sectio n.
The hydraulic reaction piston moves axially, relative to th e rotary distributor, and is connected to the control sleeve by a
three-bearing helical screw. Pressure applied either side of the hydraulic reaction piston is translated into a rotational force
which increases steering effort. For detail s of Servotronic speed-sensitive steering control, refer to Servotronic Control in
this sub-section.
When the vehicle is travelling straight ah ead, the valve restrictions are balanced, thus providing equal pressures on either
side of the rack piston. When load is a pplied at the steering wheel, the two halves of the control valve (rotary distributor
and control sleeve) are displaced making the restrictions unequa l. The resulting differential pressures on either side of the
rack piston, assist the steering rack to mo ve to left or right. As the turning load is removed, the pressures equalize again
and the steering return s to the straight ahead position , aided by suspension geometry.
Serv
otronic Control

P a
rts List
The Servotronic system provides steering assistance which is pr oportional to vehicle speed. It comprises the steering control
module, and Servotronic valve forming part of the hydraulic control valve assembly.
The Servotronic valve is an electro-hydrauli c device with a variable orifice, which varies in size according to the position of a
needle valve. The needle valve is controlled by a solenoid in response to a variable current input from the steering control
Ite
m
Part
Number
Descr
iption
1—Vehi
cl
e speed input
2—Steeri
ng control
module
3—Servotronic valve
4—Hydraulic

control valve housing
5—PAS stee
rin
g pump
6—Batt
ery

Power Steering - Steering Gear
Remo
val and Installation
Remov
a
l
All vehicles
S
p
ecial Tool(s)

Taper Sep
a
rator
211-098 (JD 100)
1. Centralize steeri ng the wheel.
2. Raise and support the vehicle on a four-post ramp.
3. Place a suitable drain pan under the stee ring gear.

4. Fr
om below the vehicle, check that
steering gear is centralized
by aligning the centralizing notc h on the dirt protection cover
with the location hole in the pinion housing casting.

5. NOTE : R
ight-hand shown, left-hand similar.
Remove and discard bo th tie rod end nuts.

6. NOTE : R
ight-hand shown, left-hand similar.
Detach both of the tie rod ends.
1. Fit the special tool to tie rod end.
2. Tighten the tool bolt to release the taper.
Re
move the tool.

Locate the ti
e rod end into the steering arm.
Inst

all a new nut.
Tigh

ten the nut to 22-28 Nm.

12
.
NOTE: Make sure the steering wheel and wheel and tire
assemblies are in the straight ah ead position before fitting the
steering column lower shaft.
Attach the steering column lower shaft.
1. Attach the steering column lower shaft.
2. Install the steering column lower shaft retaining bolt.
1. Tighten to 28 - 34 Nm
.
3

. Tighten to 28 - 34 Nm.
13. Fit a new power steering fluid re servoir, refill with new power
steering fluid and blee d air from the system.
For additional information, refer to: Power Steering System
Fillin
g and Bleeding

(211-00 Steering System - General
Information, Gene ral Procedures).
14. Check and adjust the front toe.
For additional information, refer to: Front Toe Adjustment

(204-00 Suspen
sion System -
General Information, General
Procedures).