2001 BMW 525i Air suspension

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31 0-4
I Front Suspension
6-cylinder models
12 3 4 5
V-8 models
16 7 4
Front suspension
variations
1. Steering knuckle
2. Tension strut (thrust arm)
3. Steering rack
4. Front suspension
subframe
5. Outer tie rod
6. Control arm
7. Steering box
8. Idler arm
9. Center tie rod
The front suspension
shoclc absorbers on E39 cars are
MacPherson struts. The strut is a major component of the
front suspension and supports the spring. Most strut assem-
bly components are available as replacement parts. Always
replace struts and springs in pairs.
Front strut, upper strut mount or spring replacement is a two-
step procedure:
Removal of strut assembly from vehicle
Disassembly and replacement of component on
work
bench

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Front Suspension
/ Front strut top mount assembly
< Replace springs in matched pairs only. BMW ID number is
stamped near end
(A).
4 Assembly is reverse of disassembly, noting the following:
Use a new upper strut self-loclting nut
(A). Tighten nut
fully before releasing spring compressor.
CAUTION-
Do not tighten strut nut with impact tool.
NOTE-
illustration shows components for 6-cylinder models (5257,
528i, 5300. V-8 models (5400 are similar but not identical.
4 Be sure upper and lower spring pads (arrows) are correctly
installed to spring seats before releasing spring compressor.
Release spring compressor carefully and evenly, allowing
spring to expand slowly.
Have car professionally aligned when job is complete.
Tightening torques Upper strut mount to strut shaft
64 Nm (47 ft-lb)
Strut mount to strut tower (ME) 24 Nrn (18 fi-lb)

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/~ront Susaension
Front suspension arms FRONT SUSPENSION ARMS
Scyllnder models (5251,5281,530i)
Control arms and tension struts are attached to the front sub-
Front suspension arms V-8 models (5401)
frame through rubber bushings and to the steering ltnuckles
by ball joints.
NOTE-
Tension struts are sometimes called thrust arms or thrust
rods.
Control arms or tension struts are sometimes called lower
front arms or lower rear arms.
Inspect ball joints for wear and looseness. lnspect bushings
for wear or fluid
lealts. The ball joint can only be replaced as
part of an entire suspension arm assembly. Some suspen-
sion arm
bushinas are available as re~lacement Darts. Al-
ways replace in pairs
NOTE-
Steering wheel vibration during braking (usually at road
speeds of
50 to 60 m.p.h.) are often causedby faulty suspen-
sion arm bushings, not out-of-true brake rotors.
Some special tools may be required to remove suspension
arms and to replace bushings. Read procedures through be-
fore beginning the job.
Control arm, removing and installing
(6-cylinder models)
- Raise car and remove wheel
Male sure
that the car is firmly supported on jack stands de-
signed for the purpose. Place jack stands underneath struc-
tural chassis points. Do not place jack stands under
suspension
parfs.
Cars equipped with vertical headlight adjustment system:
Disconnect control arm from level sensor.
Remove control arm fasteners (arrows). Lightly tap inner
control arm mounting bolt out of subframe.

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Steering and Wheel ~li~nrnentl
Steering gearbox, removing and installing
- Disconnect negative (-) battery cable. See 020 Mainte-
nance.
CAUTION-
Prior to disconnecting the battew read the battery discon-
nection cautions given in
001 General Cautions and
Warnings.
- Remove airbag unit from steering wheel. See 721 Airbag
System (SRS).
WARNING -
Improper handling of the airbag could cause serious injury
Store the
airbag with the horn pad facing up. If stored lacing
down, accidental deployment couldpropel it violently info the
air, causing
injuv
- Remove steering wheel as described earlier.
- Drain power steering system reservoir.
- Raise front of car.
WARNING -
Make sure the car is firmly supported on jack stands de-
signed for the purpose. Place jack stands beneath structural
chassis points. Do not place jack stands under suspension
Darts.
- Remove heat shield from left side of subframe.
- Remove fluid hoses from top of steering gearbox. Immedi-
ately plug all fluid openings.
Remove and discard
pitman arm self-loclting nut (arrow).

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Steerina and Wheel ~lianmentl
Proper handling, stability and driving ease depend upon the
correct alignment of all four wheels. The front axle is aligned
in relation to the rear axle, then the front wheels are aligned in
relation to one another. This is known as a four-wheel or
thrust-axis alignment.
Front and rear alignment specification are given in tables at
the end of this repair group.
BMW E39 cars use a sophisticated multi-link suspension at
the front and rear of the car. Proper alignment requires com-
puterized alignment equipment.
Camber
Front wheel camber is set at the factory and cannot be adjust-
ed. Rear wheel camber is fully adjustable.
Always set rear camber before adjusting toe
Before making rear camber adjustment, install a new rear
control arm mounting nut
(arrow) and tighten.
- Loosen mounting nut one-half to one full turn.
Using eccentric bolt, adjust camber to factory settings.
Tighten nut only after car has been lowered to ground and
suspension has settled.
Tighten nut while counterholding adjustment bolt.
Tightening torque
Camber adjusting nut (rear)
MI2 (sedan)
- MI4 (Sport Wagon)
115 Nm (85 ft-lb)
174 Nm (128 ft-lb)
Caster
Front and rear caster are fixed by the design of the car and
deviations are usually the result of worn or damaged suspen-
sion or body parts.
- Check front suspension arms and bushings for wear, dam-
age and deformation if front caster problems are present.
- Check rear axle subfrarne and traction struts if rear caster
problems are present.

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Steering and Wheel Alignment
- Tighten nut while counterholding adjusting bolt,
- Tighten nut only after car has been lowered to ground and
suspension has settled.
Preparing for alignment
- The following conditions are necessary prior to wheel align-
ment:
Correct wheels and tires are installed, in good condition,
and are at the correct inflation pressures.
All steering and suspension parts and bushings are un-
damaged and show no signs of abnormal wear. Wheel
bearings are in good condition.
Ride height is in accordance with specifications. See
300
Suspension, Steering and Brakes-General.
Car is in normal loaded position. See below.
* Cars with air suspension: Remove air suspension power
fuse.
Normal loaded position
Each front seat
68 Kg (I50 lb)
Center of rear seat
Trunlc
Fuel tank
68 Kg (150 lb)
21 Kg (46 lb)
Full
Alignment specifications tables
In the alignment specification tables that follow, reference is
made to the various types of suspension used in
E39 cars.
The type of suspension can be identified by loolting at the la-
bel on the front strut tube.
Identifying symbol
None
Solid circle
Solid triangle
M5
Circle
Triangle Version
Standard suspension
Sports
suspension
Sports suspension
M sport package
Standard suspension
Sports suspension Model
Sedan
6-cylinder sedan
V-8 sedan
V-8 sedan
Touring (Sport Wagon)
Touring (Sport Wagon)

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330 Rear Suspension
General . . . . . . . . . . . . . . . . . . . . . . . . . . . ,330-2
Special tools . . . . . . . . . . . . . . . . . . . . . . . . ,330-2
Rear suspension variations . . . . . . . . . . . . ,330-4
Rear Struts and Springs
(sedan models)
. . . . . . . . . . . . . . . . . . . . ,330-5
Rear strut assembly, removing
and installing
. . . . . . . . . . . . . . . . . . . . . . . ,330-5
Rear strut assembly, disassembling
and assembling
. . . . . . . . . . . . . . . . . . . . . ,330-7
Rear Shock Absorbers and
Springs (Sport Wagon models)
. . . . . ,330-9
Rear shock absorber, removing
and installing
. . . . . . . . . . . . . . . . . . . . . . . ,330-9
Coil spring, removing and installing . . . . . ,330-1 1
Air spring, removing and installing
. . . . . . ,330-12
Rear Suspension Arms,
Subframe and Bushings . . . . . . . . . . ,330-13
Rear suspension arm components . . . . . . ,330-1 3
Swing arm, removing and installing (sedan models)
. . . . . . . . . . . . . . . . . . . . . ,330-1 4
Swing arm, removing and installing (Sport Wagon models)
. . . . . . . . . . . . . . . ,330-16
Swing arm ball joint, replacing . . . . . . . . . ,330-1 9
Upper rear control arm, removing
and installing (sedan models)
. . . . . . . . . . .330-22
Upper rear control arm, removing
and installing (Sport Wagon models)
. . . . .330-23
Upper front control arm (traction strut),
removing and installing
. . . . . . . . . . . . . . . ,330-25
Rear axle assembly, removing and
installing (sedan models)
. . . . . . . . . . . . . ,330-26
Rear axle assembly, removing and
installing (Sport Wagon models)
. . . . . . . ,330-28
Rear subframe mounting bushings,
removing and installing
. . . . . . . . . . . . . . . .330-31
Rear Wheel Bearings . . . . . . . . . . .
Rear wheel bearing carrier, removing
and installing (sedan models)
. . . . . . .
Rear wheel bearing carrier, removing
and installing (Sport Wagon models)
. .
Rear wheel bearing, replacing . . . . . . .
Rear Stabilizer Bar
Stabilizer bar, removing and installing .
Stabilizer bar link, removing
and installing
. . . . . . . . . . . . . . . . . . . .
Electronic Height Control (EHC)
Component Replacement
. . . . . . .
Electronic height control (EHC)
components
.....................
Air compressor pump relay, removing
and installing
. . . . . . . . . . . . . . . . . . . .
EHC control module, removing
and installing
. . . . . . . . . . . . . . . . . . . .
Air supply unit, removing and installing
Ride height sensor, removing
and installing
. . . . . . . . . . . . . . . . . . . .

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330-2
I Rear Suspension
This repair group covers removal and replacement of E39
rear suspension components. A general description of sus-
pension systems and ride height specifications can be found
in 300 Suspension, Steering and Brakes - General.
CAUTIOI\C
Some E39 models are equipped with aluminum suspen-
sion components. The following cautions apply:
Due to the chemical and corrosion characteristics of
aluminum, do not bring into contact with battery acid.
- Do not clean with wire brushes with brass or iron bris-
tles. Only use brushes with stainless steel bristles.
Do not expose to flying
sparl~s from grinding/cutting op-
erations.
* Do not subject to steel welding splashes.
0 Do not expose to temperatures over 80°C (176°F).
even for shortperlods. Temperatures in painting facili-
ties are not a problem.
Special tools
Special service tools are required for some of the work de-
scribed in this repair group. Most of these tools are special-
ized press jigs and pullers that might be replaced by standard
pullers of various sizes.
Read the procedures through before beginning any job.
< Strut upper mounting nut socket
(Tool No. BMW
31 2 21 0)
I Axle shaft removal and installation set
Spring compressor (Tool No. BMW
31 3 340.31 3 350)