front suspension BMW 540i 1998 E39 Owner's Manual

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Front Suspension
< Ball joint press
(Tool No. BMW
31 2 240)
< Bushing press tools
(Tool No. BMW
31 2 2611263)
4 Spring compressor and spring holder arms
31 3 350 (Tool No. BMW 31 3 340 131 3 350)

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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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31 0-5
Front ~uspensionl
Front strut assembly, removing and
installing
- Raise car and remove front wheel.
WARNING-
Make 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
parts.
- Unbolt bralte caliper assembly, lkeeping bralte hose connect-
ed. Secure brake caliper to body with wire. Do not let it hang
from brake hose. See
340 Brakes.
Remove ABS pulse sensor mounting bolts (arrows) and re-
move sensor from housing.
Detach ABS sensor wire harness and bralte pad wear sensor
wire harness (if equipped) from strut housing.
Loosen and remove stabilizer bar link mounting nut while
counterholding
link ball joint. Disconnect stabilizer link from
strut.
NOTE-
Use a thin wrench to counterhold shaft of stabilizer bar link
ball joint.
- Cars equipped with vertical headlight adjustment system:
Disconnect control arm from level sensor.
4 Remove outer tie rod end nut. Use BMW special tool 31 2
240 or equivalent to press tie rod end out of steering arm.

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31 0-6
Front Suspension
Mark installation position of strut tube (arrow) in steering
knuckle pinch collar.
CAUTION--
Use paint, not a scribe tool, to mark location of strut tube. 1
4 Letter on strut tube designates mounting location.
- R - Right side installation position
L - Left side installation position
NOTE-
Marking the strut tube is not necessary if factory marks (L or
R) are still visible.
4 Counterhold strut tube pinch bolt (arrow)
nut. while
loosening

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31 0-8
Front Suspension
Slide strut assembly out of steering lknucltle pinch collar. If
necessary use pry bar.
CA UTIOI\C
Do notpullstrut out of steering knuckle with twisting motion.
This can scratch and damage the strut.
Disassemble and reassemble strut assembly as described
later.
When installing new strut, be sure to align locator letter (A)
on strut body with slot in steering
lknuckle pinch collar (6).
Struts are marked with L for left and R for right.
Remainder of installation is reverse of removal.
Make sure strut shoulder (below locator letter) bottoms out
in steering knuckle pinch collar.
Use new self-locking nuts and bolts.
When attaching stabilizer
lrnk to strut, use a thin wrench to
counterhold
link ball joint while t~ghtening nut.
- Have car professionally al~gned when job IS complete.
Tightening torques
Brake caliper to steering knuckle
110 Nm (81 ft-ib)
Road wheel to hub 120 ti0 Nm (89 t7 ft-lb)
Stabilizer bar
link to strut 65 Nm (48 It-lb)
Steering knucltle pinch bolt at strut 81 Nm (60 It-lb) - mountlng collar
Steering tle rod to steerlng knuckle 65 Nm (48 it-lb)
Strut assembly top to strut tower 24 Nm (18 it-lb)
- - -

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31 0-9
Front Suspension
Front strut assembly
components
(6-cylinder models)
1. Cap
2. Upper strut self-locking nut
3. Washer
4. Strut bearing reinforcement
5. Strut mount self-locking nut
6. Upper strut mount
7. Dust protector collar
8. Spacer
9. Upper spring seat
10. Spacer
11. Upper spring pad
12. Coil spring
13. Rubber stop
14. Dust boot
15. Lower strut pad
16. Strut with lower spring seat
Front strut assembly, disassembling
and assembling
Replacing the strut, upper strut mount or spring requires that
the strut assembly first be removed from the car
and disas-
sembled. For a guide to parts used during component re-
placement, see the accompanying diagram.
NOTE-
Illustration shows components ior 6-cylinder models (525i,
528i, 530;). V-8 models (540i) are similar but not identical.

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31 0-1 0
Front Suspension
4 Clamp spring compressor (BMW special tool 31 3 340 or
equivalent) in shop vise.
WARNING-
* Do not attempt to disassemble the strut assembly without
a spring compressor designed specifically for this job.
Prior to each use,
checlc special tool for functionality.
Do not use a damaged tool.
Do not make any modifications to tool. Use correct size spring retainers when compressing
coil spring.
I When assembling BMW spring compressor (special
tool
31 3 340), make sure spring retainerplates are felt
and heard snapping into place. Check seating of spring
retainers carefully.
Position coil spring between spring holders so that
3 coils lie
between spring holders
(arrows). Compress spring.
WARNING -
When tensioned, the spring coils must rest completely in
the spring holder recess.
Never tighten or loosen spring compressor with an im-
pact tool.
Only tighten down the coil springs until stress on the
thrust bearing is relieved.
a Only loosen strut nut if spring coils are completely in-
serted in the spring holder grooves. If
necessarx loos-
en compressor, reposition and recompress.
Use
BMW special tool 31 2 21 0 or equivalent to remove strut
nut. Counterhold strut shaft using
6 mm Allen wrench.
CAUTION-
Do not remove strut nut with impact tool.
Remove upper strut bearing and related components.
If a new coil spring is being installed, relieve tension on
spring compressor and remove coil spring.
Check strut dust boot, rubber stop and spring pads. Replace
as necessary.
Replace strut, upper strut mount or spring, as needed

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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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Front Suspension
< Use BMW special tool 31 2 240 or equivalent to separate
control arm ball joint from steering ltnuckle.
- When installing control arm, make sure all thread bores.
bolts, nuts and mating surfaces are clean.
- Install bushing end of control arm to subframe, using wash-
ers on both sides of bolt and a new self-locking nut. Do not
tighten nut at this time.
- Install control arm ball joint to steering lknucltle using a new
self-locking nut. Tighten fully.
- Install wheel and lower car.
- Load car to normal loaded position as described under Ride
height. See
300 Suspension, Steering and Brakes-Gen-
eral. Bounce suspension a few times.
- With car on ground and loaded, tighten control arm bushing
through-bolt.
Tightening torques
Control arm to steering ltnuckle
80 Nm (59 ft-lb)
Control arm to subframe 110 Nm (81 It-lb)
Road wheel to hub 120ilO Nm (8957 it-lb)
Control arm, removing and installing
(V-8 models)
- Raise car and remove wheel
WARNING-
Make sure that the car is firmly supported on jack stands de-
signed for the purpose. Place jack stands underneath struc-
tural
cliassis points. Do not place jack stands under
suspension parts.
Loosen and remove stabilizer bar link mounting nut
(A) while
counterholding ball joint
(B). Disconnect stabilizer link from
stabilizer bar.
- Cars equipped with vertical headlight adjustment system:
Disconnect control arm from level sensor.