DISA BMW 528i 1998 E39 Owner's Manual

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300-1 4
I Susoension. Steerina and Brakes - General
DSC system I
Dynamic Stability Control (DSC)
Dynamic Stability Control (DSC) utilizes many principles and
components of the ASC traction control system. DSC is ac-
tive throughoutthe driving range, unlike ASC which is only ac-
tive during acceleration and braking. DSC helps stabilize the
vehicle in cornering and avoidance maneuvers by adjusting
engine controls such as throttle, ignition, fuel injection and the
application of
brake pressure individually to the wheels.
Inputs
fi- 0
2 4-* .. o
[11-' IJ
411m4
3?-
G
4 The DSC control module uses various inputs to determine
vehicle instability during braking, cornering, or reduced trac-
tion situations. Based upon these inputs the ABSIDSC con-
trol module sends outputs to the engine control module and
the ABSIDSC hydraulic unit to activate torque reduction pro-
tocols and braking intervention.
-
ABSIDSC control module
OUI~YIS
4
The DSC system can be toggled on and off by a switch
mounted on the center console. Turning off the DSC system
does not disable ABS or ASC functions.
+
Measure ride height (A) from center of fender arch to bottom
of wheel rim.
Car in normal loaded position on the ground. See Normal
loaded position.
Engine
control
module
Specified tires and wheels, correct tire pressure, even tire
wear
-'* 9-
.%A
Correct wheel bearing play
T'== ..t, 9 B
-.m
Model with air suspension (EHC): Disconnect electrical har-
ness connector to air supply pump to prevent automatic
height regulation.
When finished, reset ride height using BMW diagnostic
scan tools DIS or
MoDiC.
NOTE-
Airsupply pump is located beneath a cover under the spare
tire in the floor of the cargo compartment.
- If ride height is outside specification listed, install new
springs. Suspension spring removal and installation is cov-
ered in
310 Front Suspension and 330 Rear Suspension.
Normal loaded position
Each front seat 68 kg (150 Ib)
Center of rear seat 68 kg (150 lb)
Trunk 21 kg (46 lb)
Fuel tank full

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31 0 Front Suspension
General . . . . . . . . . . . . . . . . . . . . . . . . . . . .310-2 Front Suspension Arms . . . . . . . . . . . 310-1 2
Special tools . . . . . . . . . . . . . . . . . . . . . . . . ,310-2 Control arm, removing and installing
Front suspension variations
. . . . . . . . . . . . ,310-4 (6-cylinder models) . . . . . . . . . . . . . . . . . . 31 0-1 2
Control arm, removing and installing Front Strut ' ' ' ' ' ' ' ' ' ' ' ' ' ' '310-4 ("-8 models) , , , , , , , , , , , , , , , , , , , , , , , 310-13 Front strut assembly, removing
Tension strut, removing and installing . . . . 310-16 and installing . . . . . . . . . . . . . . . . . . . . . . . . ,310-5 Tension strut bushing, replacing . . . . . . . . 310-18 Front strut assembly components
(6-cylinder models)
. . . . . . . . . . . . . . . . . . ,310-9 Wheel Bearings, Front . . . . . . . . . . . . . 310-18
iron; strut assembly, disassembling Front Stabilizer Bar . . . . . . . . . . . . . . . 310-22 and assembling . . . . . . . . . . . . . . . . . . . . . ,310-9 Stabilizer bar, removing and installing . . . . 310-22

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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 0-8
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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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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330-6
Rear Suspension
4 Remove rear strut top cover. Remove upper strut mounting
nuts (arrows).
Remove strut assembly lower mounting bolt (arrow).
Disassemble strut and spring assembly as described below
in Rear strut assembly, disassembling and reassem-
bling.
Installation of assembly to car is reverse of removal, noting
the following:
Make sure all threaded bolts, nuts and mating surfaces are
clean.
Install strut assembly top mount using new self-loclting
nuts.
Malte sure long lower strut bushing fits in
hole in wheel
bearing carrier.
Tightening torques Strut to wheel bearing carrier 127 Nm (94
it-lb)
Strut mount to body
Gray fasteners 28 Nm (21 ft-lb)
Yellow fasteners 24 Nm
( 18 it-lb) -
Road wheel to hub 120ilO Nm (89i7ft-lb)

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Rear ~us~ensionl
Rear strut assembly, disassembling and
assembling
Replace struts and coil springs in pairs only
Replacing the upper strut mount, spring or strut requires that
the strut assembly first be removed from the car, as described
earlier. Strut disassembly requires a spring compressor.
WARNING-
Do not attempt to disassemble the strut without a spring com-
pressor designed specifically for the job.
- Remove strut assembly from car as described in Rear strut
assembly, removing
bnd installing
4 Mount spring compressor (BMW special tools 31 3 340 and
31 3 350 or equivalent) in shop vice. Install correct-sized
spring retainers
(A).
WARNING-
Do not attempt to disassemble the struts without a spring
compressor designed specifically for this job.
* Prior to using the spring compressor checlc its opera-
tion. Do not use a spring compressor that is damaged.
Do not make any modifications to the spring compres-
sor.
Never use an impact wrench to compress or relieve
tension when using a spring compressor.
1
- Place strut assembly coil spring in spring retainers. Com-
press spring until force on upper strut mount is relieved.
Remove strut top mount self-locking nut with BMW special
tool
31 2 21 0 while counterholding strut shaft with a box end
wrench.
- Remove upper strut mount and related components. Sepa-
rate strut from spring.
NOTE-
Store the removed shock absorber upright Do not allow it to
lie horizontally or upside down for any length of time. If incor-
rect storage has occurred, place the
shoclc absorber upright
with the rod
fully extended for at least 24 hours.
- Replace strut, rubber bumper, upper strut mount or spring,
as needed.
NOTE- Relieve tension on spring compressor slowly and carefully.
Fit new spring in spring compressor so that one coil at
each end is outside spring retainer.