1999 LAND ROVER DISCOVERY air suspension

FRONT SUSPENSION
60-60 REPAIRS
7.Remove 2 cap nuts securing pipes to ACE rear
actuator. Disconnect pipes, remove and
discard sealing washers.
CAUTION: Always fit plugs to open
connections to prevent contamination.
8.Remove 2 nuts securing rear pipe clamping
plate. Release clamping plate and pipes from
valve block.
CAUTION: Always fit plugs to open
connections to prevent contamination.
9.Remove pipe assembly.
10.Remove collets and clamping plate from rear
pipes. Refit
1.Ensure valve block and pipe connections are
clean.
2.Install clamping plate and collets on rear pipes.
3.Position pipe assembly to vehicle and connect
pipes and clamping plate to valve block. To
avoid damage to seals, keep pipes square
to valve block. Fit and tighten nuts securing
clamping plate to valve block to 21 Nm (15
lbf.ft).
CAUTION: Ensure pipes are installed in
their correct ports or serious system
damage will occur.
4.Fit bolts securing rear pipe clips to chassis and
tighten to 6 Nm (4.4 lbf.ft).
5.Connect pipes to actuator with cap nuts and
new sealing washers. Tighten cap nuts to 29
Nm (21 lbf.ft). Ensure pipes are not under
tension or kinked.
6.Ensure washer is in place on lower ball joint of
each anti-roll bar link, then connect lower ball
joints to axle and tighten nuts to 100 Nm (74
lbf.ft).
7.Renew ACE high pressure filter.

+ FRONT SUSPENSION, REPAIRS,
Filter - high pressure - ACE.
8.Bleed ACE hydraulic system.

+ FRONT SUSPENSION,
ADJUSTMENTS, ACE hydraulic system
bleeding.
9.Lower vehicle.

FRONT SUSPENSION
REPAIRS 60-61
Actuator - front - ACE
$% 60.60.40
CAUTION: The ACE hydraulic system is
extremely sensitive to the ingress of dirt or
debris. The smallest amount could render the
system unserviceable. It is imperative that the
following precautions are taken.
lACE components are thoroughly cleaned
externally before work commences;
lall opened pipe and module ports are
capped immediately;
lall fluid is stored in and administered
through clean containers.
Remove
1.Raise vehicle on a ramp.
2.Remove RH front road wheel.
3.Position container to collect fluid spillage.
4.Remove cap nuts securing fluid pipes to
actuator. Disconnect pipes and discard sealing
washers.
CAUTION: Always fit plugs to open
connections to prevent contamination.5.Remove 2 nuts securing anti-roll bar links to
axle. Release links from axle.
6.With assistance, remove 2 bolts and remove
both clamp plates from torsion bar.
7.Remove mounting rubbers from torsion bar.
8.Remove torsion bar and actuator assembly.
CAUTION: While removed from the vehicle,
ensure torsion bar is stored without any
load on the anti-roll bar links, or the ball
joints and/or link rods could be damaged.

FRONT SUSPENSION
60-62 REPAIRS
9.Use LRT-60-009 to remove nut securing
actuator to long arm.
10.Remove nut and bolt securing actuator to short
arm and remove actuator.
CAUTION: The short arm and torsion bar
are supplied as an assembly and must not
be separated.Refit
1.Fit actuator to torsion bar. Use LRT-60-009to
tighten actuator to long arm nut to 48 Nm (35
lbf.ft). Tighten actuator to short arm nut and bolt
to 180 Nm (133 lbf.ft).
2.Ensure torsion bar mounting rubber mating
faces are clean and free from damage.
3.Fit mounting rubbers to torsion bar.
4.With assistance, position torsion bar and
actuator assembly to vehicle. Fit clamp plates
and tighten bolts to 45 Nm (33 lbf.ft).
5.Ensure washer is in place on lower ball joint of
each anti-roll bar link, then connect lower ball
joint to axle and tighten nuts to 100 Nm (74
lbf.ft).
6.Connect pipes to actuator with cap nuts and
new sealing washers. Tighten cap nuts to 29
Nm (21 lbf.ft). Ensure pipes are not under
tension or kinked.
7.Renew ACE high pressure filter.

+ FRONT SUSPENSION, REPAIRS,
Filter - high pressure - ACE.
8.Bleed ACE hydraulic system.

+ FRONT SUSPENSION,
ADJUSTMENTS, ACE hydraulic system
bleeding.
9.Fit RH front road wheel and tighten nuts to 140
Nm (103 lbf.ft).
10.Lower vehicle.

FRONT SUSPENSION
REPAIRS 60-63
Bushes - front long arm - ACE
$% 60.60.46
Remove
1.Remove ACE front actuator.

+ FRONT SUSPENSION, REPAIRS,
Actuator - front - ACE.
2.Remove securing nut and remove anti-roll bar
link from torsion bar.
3.Restrain torsion bar and remove long arm
securing bolt and washer. Remove long arm
from torsion bar.
CAUTION: The short arm and torsion bar
are supplied as an assembly and must not
be separated.
4.Use a suitable drift to remove both halves of
slipper bush from long arm.
5.Use suitable adaptors to press actuator rod end
bush from long arm.Refit
1.Clean bush locations in long arm.
2.Use suitable adaptors to press new actuator
rod end bush into long arm. Ensure hole in bush
is correctly aligned with hole in long arm.
3.Align slots in new slipper bush halves with
those in long arm. Carefully press both halves
of slipper bush into long arm. Ensure the
sealing rings on the slipper bush faces are not
damaged.
4.Clean long arm and mating face on torsion bar.
5.Fit long arm to torsion bar. Restrain torsion bar
and tighten bolt to 180 Nm (133 lbf.ft).
6.Fit anti-roll bar link to long arm and tighten nut
to 50 Nm (37 lbf.ft).
7.Fit ACE front actuator.

+ FRONT SUSPENSION, REPAIRS,
Actuator - front - ACE.

REAR SUSPENSION
64-2 DESCRIPTION AND OPERATION
Rear suspension component layout
(vehicles with SLS)
1Air pressure pipe connector
2Damper RH
3Watts linkage
4Anti-roll bar link LH
5Air spring LH
6Damper LH
7Torsion/Anti-roll bar
8Radius arm LH9ACE short arm (if fitted)
10ACE actuator (if fitted)
11ACE long arm (if fitted)
12Anti-roll bar link RH
13Radius arm RH
14Rear axle
15Air spring RH

REAR SUSPENSION
DESCRIPTION AND OPERATION 64-5
1Rear axle
2Bolt
3Bush
4Locknut
5Transverse link
6Locknut
7Bolt
8Locknut
9Bush
10Bush
11Bolt
12Bolt
13Transverse link
14Bolt
15Bush
16Pivot housing
17Locknut
18Bush
19Lower spring seat 2 off
(vehicles without SLS only)
20Bolt 4 off (vehicles without SLS only)
21Coil spring 2 off (vehicles without SLS only)
22Spring seat isolator 2 off
(vehicles without SLS only)
23Clip 4 off (vehicles with SLS only)
24Air spring 2 off (vehicles with SLS only)25Locknut
26Bush 2 off
27Locknut 2 off
28Radius arm LH
29Locknut
30Torsion/Anti-roll bar link LH
31Washer
32Locknut
33Anti-roll bar assembly
34Mounting rubber 2 off
35Clamp plate 2 off
36Bolt 2 off
37Locknut
38Washer
39Anti-roll bar link RH
40Locknut
41Radius arm RH
42Bush 2 off
43Locknut 2 off
44Locknut 2 off
45Bush 2 off
46Bolt 2 off
47Bolt 2 off
48Bolt 2 off
49Damper 2 off

REAR SUSPENSION
64-6 DESCRIPTION AND OPERATION
Description
General
The rear suspension comprises two dampers, two radius arms, a Watts linkage and an anti-roll bar assembly. On
vehicles without Self Levelling Suspension (SLS) coil springs are used. On vehicles with SLS air springs are used.
The anti-roll bar is an essential part of the rear suspension. On vehicles without ACE, a conventional 'passive' anti-
roll bar is fitted. On vehicles fitted with the ACE system, a thicker diameter anti-roll bar, known as a torsion bar, is used
with an actuator at one end.

+ FRONT SUSPENSION, DESCRIPTION AND OPERATION, Description - ACE.
The hydraulic dampers and springs provide springing for each rear wheel. The long travel dampers, springs and
radius arms provide maximum axle articulation and wheel travel for off-road driving. The rear axle is controlled
longitudinally by two forged steel radius arms and transversely by a Watts linkage.
Radius arms
Each radius arm is manufactured from forged steel. Two bushes are pressed into the rear of the radius arm. The rear
of the radius arm is located between a fabricated bracket on the axle and secured through the bushes with two bolts
and nuts. A bush is pressed into the forward end of the radius arm which is located in a fabricated bracket on each
chassis longitudinal and secured through the bush with a bolt and nut. Each radius arm is similar in its construction
to the front radius arms. The rear radius arms are shorter than the front and have a lug for attachment of the SLS
height sensor (when fitted).
The radius arms prevent longitudinal movement of the rear axle and because of their length allow maximum axle
articulation. The stiffness of the bushes in each radius arm also contributes to the vehicle roll stiffness.
Each radius arm has a notch on its lower edge which provides location for the vehicle jack.
Dampers
Two conventional telescopic dampers are used to control body/axle movement. The upper damper mounting is fitted
with a bush which locates in a bracket on the chassis longitudinal. The damper is secured with a bolt which screws
into a captive nut on the bracket. The lower damper mounting is also fitted with a bush and locates in a fabricated
bracket attached to the rear axle. The lower mounting is secured with a bolt which screws into a captive nut on the
bracket. The upper and lower bushes are replaceable items.
Air springs (vehicles with SLS)
On vehicles with SLS fitted, air springs are fitted between the rear axle and the chassis. Each spring is located at its
base on a fabricated platform on the rear axle. The top of the spring locates in a fabricated bracket attached to the
outside of each chassis longitudinal.
The plastic base of the air spring has two lugs which locate in a slotted hole in the rear axle platform. The spring is
secured by rotating the spring through 90°, locating the lug in the platform. The plastic top of the air spring has two
grooved pins which locate in holes in the bracket on the chassis. Two spring clips locate on the grooved pins and
retain the top of the spring in position.
Each air spring comprises a top plate assembly, an air bag and a base piston. The air bag is attached to the top plate
and the piston with a crimped ring. The air bag is made from a flexible rubber material which allows the bag to expand
with air pressure and deform under load. The top plate assembly comprises the plastic top plate with two bonded
grooved pins on its top face. In the centre of the top face is a female connector which allows for the attachment of the
air hose from the SLS compressor. The piston is made from plastic and is shaped to allow the air bag to roll over its
outer diameter. The base of the piston is recessed with a boss moulded in the centre. The boss has two lugs which
provide attachment to the axle platform.
Coil springs (vehicles without SLS)
On vehicles without SLS fitted, coil springs are fitted between the rear axle and the chassis in place of the SLS air
springs. Each spring is located at its base by the lower spring seat which is secured to a fabricated platform on the
rear axle with two bolts. The top of each spring is located in the upper spring seat. The upper spring seat comprises
a pressed metal plate with an outer coating of natural rubber bonded to the plate. The upper spring seat is retained
in position by the compression of the spring.

REAR SUSPENSION
64-8 DESCRIPTION AND OPERATION
Anti-roll bar
The anti-roll bars fitted differ between ACE and non-ACE vehicles. On non-ACE vehicles a conventional 'passive' anti-
roll bar is used. On ACE vehicles an 'active' torsion bar is used. Both types are attached to the tubular cross-member
at the rear of the chassis with mounting rubbers and clamp plates. The clamp plates locate in fabricated brackets
attached to the tubular cross-member and secured with bolts.
Each end of the anti-roll bar is attached to an anti-roll bar link. Each link has a spherical bearing attached at each end.
One end is attached to a bracket on the axle and secured with a locknut. The opposite end attaches through a hole
in the anti-roll bar and is also secured with a locknut. On 'active' torsion bars, the RH anti-roll bar link is attached to a
long arm which in turn is attached to the anti-roll bar.
Passive anti-roll bar
The passive anti-roll bar is a conventional anti-roll bar which opposes axle movement, reducing the effects of lateral
forces on the vehicle body.
With the conventional passive anti-roll bar, axle movement is opposed by the anti-roll bar through links attached to
the axle casing and each end of the anti-roll bar.
On vehicles with coil springs (no SLS fitted) the anti-roll bar is manufactured from 19 mm (0.74 in.) diameter spring
steel bar.
On vehicles with air springs (SLS fitted) the anti-roll bar is manufactured from 29 mm (1.14 in.) diameter spring steel
bar.
Active torsion bar

+ FRONT SUSPENSION, DESCRIPTION AND OPERATION, Description - ACE.The 'active' torsion bar is
used in conjunction with the ACE system to control body roll and directional stability giving a reduction of the effects
of lateral forces on the vehicle body over a conventional 'passive' anti-roll bar.
The torsion bar opposes axle movement by the application of a hydraulic force to oppose the lateral forces through
links attached to the axle casing and each end of the bar. The torsion bar is made from 35 mm (1.4 in.) diameter spring
steel. One end is fitted with an arm which is operated by a hydraulic actuator to oppose corning forces.