1998 JAGUAR X308 lamp

Are th
ere any external brake system leaks?
Yes REPAIR as necessary. ADD fluid and BLEED the brak e system. For additional information, refer to
General Procedures in this section. TEST the system for normal operation.
No GO to F3
.
F
3: CARRY OUT A BRAKE MASTER CYLINDER BYPASS TEST
Te

st for brake master cylinder bypass condition. Re
fer to Brake Master Cylinder Component Test in
this section.
1
A
re any concerns found?
Yes INSTALL a new brake master cylinder, ADD flui d and BLEED the brake system. For additional
information, refer to General Proc edures in this section. TEST the system for normal operation.
No System is OK.
PINPO
INT TEST G : EXCESSIVE BRAKE PEDAL EFFORT
TE
ST
CONDITIONS
D
ETAILS/RESULTS/ACTIONS
G1

: CHECK BRAKE PADS
Check the brake pads for wear, contamin

atio
n, correct installation, damage and type.
1
A
re any concerns found?
Yes INSTALL the front brake pads correctly or INSTALL ne w front brake pads if necessary. For additional
information, refer toSection 206
-03
Front Disc Brake
. INSTALL the
rear brake pads correctly or
INSTALL new rear brake pads if necessary. For additional information, refer toSection 206
-04
Rear
Di

sc Brake
. REPEAT road test.
No

GO to G2
.
G2:
CHECK VACUUM
Di

sconnect the vacuum booster hose from the booster.
1
Conne

ct a vacuum/pressure tester to the vacuum hose.
2
Ru

n the engine at normal operating temperature.
3
Re

cord the vacuum reading.
4
Is

the reading 40.5kPa (1
2 in-Hg) or greater?
Yes GO to G3
.
No

LOCATE and REPAIR the source of low vacuum . TEST the system for normal operation.
G3
: INSPECT SYSTEM
Swi

tch the engine off.
1
Re

connect the vacuum hose.
2
Inspect th

e brake booster, rubber grommet, and al
l vacuum plumbing for cracks, holes, damaged
connections, or missing clamps.
3
Pump th
e brake pedal several time
s to exhaust the vacuum. Push down on the brake pedal and hold.
4
Does th
e brake pedal move down
when the engine is started?
Yes Vacuum system is OK.
No GO to G4
.
G4
: CHECK POWER BRAKE BOOSTER VALVE
Check the brake booster valve. For
add
itional information, refer to
Brake Booster in this section.
1
Is th
e power brake booster valve OK?
Yes CHECK the brake booster. Fo r additional information, refer to Brak e Booster in this section. INSTALL a
new brake booster if necessary. TEST the system for normal operation.
No INSTALL a new brake booster valve. TEST the system for normal operation.
P
INPOINT TEST H : BRAKE LOCKUP
DURING LIGHT BRAKE PEDAL FORCE
TE
ST
CONDITIONS
D
ETAILS/RESULTS/ACTIONS
H1

: TEST BRAKE LOCKUP

Comp
onent Tests
Bra
k
e Booster
1.
1. Chec k all
hoses and connections. All unused vacuum connectors should be capped. Hoses and their connections
should be correctly secured and in good condition with no holes and no collapsed areas. Inspect the valve on the
brake booster for damage.
2. 2. Check the hydraulic brake system for leaks or low fluid.
3. 3. With the transmission in PARK, stop the engine and apply the parking brake. Pump the brake pedal several times
to exhaust all vacuum in the system.
4. 4. With the engine switched off and all vacuum in the system exhausted, appl y the brake pedal and hold it down.
Start the engine. If the vacuum system is operating, the brake pedal will tend to move downward under constant
foot pressure. If no motion is felt, the vacuum booster system is not functioning.
5. 5. Remove the vacuum hose from the brake booster. Manifold vacuum should be available at the brake booster end
of the hose with the engine at idle speed and the transm ission in PARK or NEUTRAL. Make sure that all unused
vacuum outlets are correctly capped, hose connectors are correctly secured and vacuum hoses are in good
condition. When it is established that manifold vacuum is available to the brake booster, connect the vacuum hose
to the brake booster and repeat Step 3. If no downward movement of the brake pedal is felt, install a new brake
booster.
6. 6. Operate the engine for a minimum of 10 seconds at a fast idle. Stop the engine and allow the vehicle to stand for
10 minutes. Then, apply th e brake pedal with approximately 89 N ( 20lb) of force. The pedal feel (brake
application) should be the same as that noted with the engine running. If the brake pedal feels hard (no power
assist), install a new valve and then re peat the test. If the brake pedal still feels hard, in stall a new brake booster.
If the brake pedal movement feels spongy, bleed the brak e system. For additional information, refer to General
Procedures in this section.
Bra k
e Master Cylinder
Usual
l
y, the first and strongest
indicator of anything wrong in the brake syst em is a feeling through the brake pedal. In
diagnosing the condition of the brake master cylinder, check pedal feel as evidence of a brake concern. Check for brake
warning lamp illumination and the brake fluid le vel in the brake master cylinder reservoir.
Normal Conditio
ns
The fo
llowing conditions are considered norm
al and are not indications that the brake master cylinder is in need of repair.
New bra
ke systems are designed to produc
e a pedal effort that is not as hard as in the past. Complaints of light
pedal efforts should be compared to the pedal effort s of another vehicle of the same model and year.
The fl
uid level will fall with brake pad wear.
Abnormal Conditions
•

NOTE: Prior to carrying out any diag
nosis, make sure the brake system warning indicator is functional.
Changes in the brake pedal feel or brake pedal travel are in dicators that something could be wrong in the brake system. The
diagnostic procedure and techniques use brake pedal feel, warning indicator illu mination and low brake fluid level as
indicators to diagnosing brake system co ncerns. The following conditions are cons idered abnormal and indicate that the
brake master cylinder is in need of repair:
Brake ped a
l goes down fast. Th
is could be caused by an ex ternal or internal leak.
Brake pedal goes down slowly
. This could be
caused by an internal or external leak.
Brak
e pedal is low or feels spongy. This condition may be ca
used by no fluid in the brake master cylinder, reservoir

Front Disc Brake - Front Disc Brake
Description and Operation


The brake disc is mounted on the wheel studs and is clamped between the wheel and hub. Cooling ducts run through the
center of the brake disc to provide the required ventilation to keep the disc cool under operating conditions.
The caliper carrier, which is se cured to the vertical link by two bolts, carries the single-pis ton caliper housing. The caliper
housing is secured to the caliper carrier by two guide-pins and an anti-rattle spring. When the brakes are applied the
caliper-housing piston pushes th e brake pad in front of it, towards the brake di sc. This movement forces the caliper housing
to move along the guide-pins, in the oppo site direction of the piston, to apply the second brake pad. The brake disc is
therefore gripped between the two pads. As brake pressure is increased the grip on the brake disc is increased to slow-down
the rotation of the road wheel.
The disc brakes requ ire no adjustment.
It
e
m
Par
t
Number
De
scr
iption
1—B
r
ake Disc
2—Caliper Housin
g
3—Caliper Carrier
4—Brake Pads
5—Guide P i
ns
6—Du
st
Covers
7—An
ti
-rattle Spring
8—Du
st
Shield
9—Brake Hos
e

10—Bleed Nipp
le

• C
AUTIONS:
The Brembo caliper is aligned to the brak e disc when it is first installed to the vehicle, therefore, care must be taken
not to disturb this alignment. When removi ng the caliper; remove the bolts that secure the anchor bracket to the vertical
link only. DO NOT loosen any other caliper bolts.
Do not loosen bolts securing brake disc to disc mounting.
Brembo calipers and discs provide higher -performance braking using the existing hydraulic braking system. The brakes are
installed to the vehicle using unique vertical links, hubs, hydraulic hoses and disc shields.
The front brake disc consists of a ventilated, cross-drilled disc, bolted to a disc carrier. The disc assemb ly is mounted on the
wheel studs and clamped be tween the wheel and hub.
A unique feature of the front disc is th e slanted (non radial) ventilation webs which lean the opposite-way to the disc's
direction of rotation. This design enables he at generated by the disc to be dispersed by air entering at the disc's center and
being forced outwards through the cooling ducts.
Due to the use of fixed calipers in place of the standard floating caliper, certain lateral dimensions on the vertical link and
It
em
Par
t Number
De
scription
1—B

rake Disc
2—Caliper


3—Anch

or Bracket
4—Anchor Pl

ate to Vertical Link - Bolts
5—Brake Pad

s
6—Guide P

ins
7—Anti-r

attle Spring
8—Di

sc Shield
9—Brake Hos

e
10—Bleed Nipp

les


Front Disc Brake—
Brembo

Rear
Disc Brake - Rear Disc Brake
Description an
d Operation

The brake disc is mounted on the wheel studs and is clamped between the wheel and hub. Cooling ducts run through the
center of the brake disc to provide the required ventilation to keep the disc cool under operating conditions.
The caliper carrier, which is se cured to the hub carrier by two bolts, carries the single-piston caliper housing. The caliper
housing is secured to the caliper carrier by two guide-pins and an anti-rattle spring. When the brakes are applied the
caliper-housing piston pushes th e brake pad in front of it, towards the brake di sc. This movement forces the caliper housing
to move along the guide-pins, in the oppo site direction of the piston, to apply the second brake pad. The brake disc is
therefore gripped between the two pads. As brake pressure is increased the grip on the brake disc is increased to slow-down
the rotation of the road wheel.
The disc brakes requ ire no adjustment.
It
em
Par
t Number
De
scription
1—B

rake Disc
2—Caliper Housin

g
3—Caliper Carrier
4—Brake Pad

s
5—Guide P

ins

6—Du
st Covers
7—An

ti-rattle Spring
8—Du

st Shield
9—Brake Hos

e
10—Bleed Nipp

le

CAUTI O
N: The Brembo caliper is aligned to
the brake disc when it is first installed to the vehicle, therefore, care must
be taken not to disturb this alignment. When removing the ca liper; remove the bolts that secure the anchor bracket to the
hub carrier only. DO NOT loos en any other caliper bolts.
Brembo calipers and discs provide higher -performance braking using the existing hydraulic braking system. The brakes are
installed to the vehicle using unique hub carr iers, hubs, hydraulic hoses and disc shields.
The rear brake disc is a single piece co nstruction which is ventilated and cross-drilled. The disc is mounted on the wheel
studs and is clamped between the wheel and hub. Cooling ducts run through the ce nter of the brake disc to provide the
required ventilation to keep the disc cool under operating conditions.
Modified disc shields are installed to accommodate the larger diameter discs.
Due to the use of fixed calipers in place of the standard floating caliper, certain lateral dimensions on the hub carriers and
hubs are critical to achieve correct cleara nce and operation of the brakes. Therefore special hub carriers and hubs set within
a certain tolerance are inst alled with Brembo brakes.
The four cylinder brake caliper is rigidly attached to the vert ical link via an anchor bracket. The caliper is a split assembly
with each side of the caliper, housing two pistons. The two-pairs of opposed pistons act direct ly on the brake pads mounted
one each side of the disc.
It e
m
Par
t
Number
De
scr
iption
1—Brake D
i
sc
2—Caliper Housin
g
3—Anchor Bracke
t
4—Anchor Bracket to H
u
b Carrier - Bolts
5—Brake Pads


6—Guide Pi

ns
7—An
ti
-rattle Sprin
g
8—Di
sc
Shield
9—Brake Hos
e

10—Bleed Nipp
les

Rear Disc Brake - Brembo

Parking Brake and Ac
tu
ation - Parking Brake
Description an
d Operation

Parts List
The parking-brake hand lever is mounted on the transmission tunnel and incorporates the ratchet mechanism and release
button.
The front cable is routed from the hand lever, under the carpet through to an abutment bracket adjacent to the
transmission tunnel, and then connected to the relay lever. The relay lever is attached to a mounting plate by a center bolt
on which it rotates The relay lever mounting plate straddles the transmission tunnel, the plate is secured by four bolts. The
relay lever acts as a center pu ll system to transmit the force from the hand lever to the rear brakes shoes. The equalizer
which is positioned in the center of the rear brake cables balances the force that is applied to the rear brakes.
The rear brake cables are linked together: each cable passes through the rear hub carrier and connects to a brake shoe
expander lever. Application of the parking brake causes the rear cables to pu ll on the expander levers, the expander lever
mechanism rotates on a pivot pin to force the brake shoes outwards to contact the brake drums.
The parking brake cables are adjusted by the rotation of a nu t on the adjuster rod. The parking brake shoes are adjusted by
It
em
Par
t Number
De
scription
1—Hand Le

ver
2—Front Cable


3—R

elay Lever and Mounting Plate
4—Drivesh

aft Center Mounting
5—Cable Adjuster Rod


6—Equalize

r
7—Cable Connector
8—Rear Ca

ble RH
9—Rear Ca

ble LH
10—Warn

ing Light Switch and Harness
11—War

ning Lamp

means of a manual adjustment
mechanism
at each set of shoes. Refer to General Procedur es in section 206-05.
If the vehicle is driven above 5 km/h with the parking brake applied, a warning lamp and text message will appear on the
message center. The message clears when the brake is released or the speed drops below 3 km/h.
Parking Brake Shoe Arrangement

The adjuster mech
anism enables manual
adjustment of the brake shoes.
Retai
ning pins keep the shoes in contact with the dust shield.
The brake

shoes locate into the expander lever and the adjuster mechanism.
R
e
turn springs retr
act the brake shoes when the parking brake is released.
Th
e expander lever mechanism moves the brake shoes outwar
ds, in contact with the brake drum when the parking
brake is applied.


It e
m
Par
t
Number
De
scr
iption
1—Adjust
er Me
chanism
2—R
e
taining Pins
3—Brake Sh
oe
s
4—Upper
Return
Spring
5—Lower Return Spring
6—Expander

Lever Mechanism