front suspension BMW 528i 1999 E39 User Guide

Downloaded from www.Manualslib.com manuals search engine
[~us~ension, Steering and Brakes - General
This section of the manual covers front and rear suspension,
braking and steering systems, and contains wheel, tire and
wheel alignment information and specifications. Also covered
here are the integrated braking and suspension systems in-
cluding
antilock braking (ABS), traction control (ASCIDSC),
and electronic height control (EHC).
Vehicle ride height information is at the end of this repair
group. Alignment information is in
320 Steering and Wheel
Alignment.
Aluminum suspension components
In order to reduce vehicle weight, aluminum suspension com-
ponents are used in some models. A test with a magnet will
easily reveal the metal used. If working with aluminum com-
ponents, be sure to read and follow the cautions below.
CAUTION-
* Due to the chemical and corrosion characteristics of alumi-
num, do not bring into contact with battery acid.
Do not use wire brushes with brass or iron bristles.
Only use brushes with stainless steel bristles.
Do not expose to flying sparks from
grinding/cutting op-
erations.
Do not subject to steel welding splashes.
Do not expose to temperatures over
80°C (176"F),
even for short periods. Temperatures in painting facili-
ties are not a problem.
The E39 front suspension subframe is used as a rigid mount-
ing platform for the front suspension arms, stabilizer bar and
steering gear.
The suspension arms, known as the lower control arms and
the tension struts (thrust arms), are connected to the
sub-
frame through rubber bushings. The arms are connected to
the steering
knucltles in a double pivot configuration.
Each front strut assembly includes a tubular strut and a coil
spring. The upper strut mount includes a bearing. The lower
end of each strut housing is fitted to the steering knuckle. The
integral wheel bearing and hub are bolted to the steering
Iknucltle.
6-cylinder and V-8 models use different steering systems and
other front suspension components.

Downloaded from www.Manualslib.com manuals search engine
300-3
Suspension, Steering and Brakes - General
Front suspension 6-cylinder models
(5251, 5281, 530i)

Downloaded from www.Manualslib.com manuals search engine
Suspension, Steering and Brakes - General
Front suspension V-8 models (540i)

Downloaded from www.Manualslib.com manuals search engine
300-5
Suspension, Steering and Brakes - ~enerall
The E39 rear suspension subframe is used as a rigid mount-
ing platform
forthe differential (also called final drive) and rear
suspension components. The differential is mounted to the
subframe and the subframe is bolted to the body through rub-
ber bushings which help isolate drivetrain noise and vibration.
The
€39 rear suspension is known as a modified multi-link
system. Three control arms on each side locate the rear
wheels.
The lowercontrol arm, called the swing arm, is attached to the
wheel bearing carrier through a pivoting integral link.
An eccentric mounting bolt at the rear inner mounting of the
swing arm is used for rear camber adjustment.
The inner end of the upper front control arm, called the trac-
tion strut, is also mounted with an eccentric fastener, used to
adjust rear toe.
Drive axles with constant-velocity (CV) joints at both ends
transfer power
from the differential to the road wheels.
Sedan models
The rear suspension in sedan models uses coil springs over
strut shock absorbers. The bottom of each strut bolts to the
wheel
carrier.The top strut mount attaches just below the rear
parcel shelf of the car.
Sedan models fitted with EDC (Electronic Dampening Con-
trol) use air struts.

Downloaded from www.Manualslib.com manuals search engine
300-1 0
/Suspension, Steering and Brakes - General
The steering system features variable power assist provided
by an engine-driven hydraulic pump.
Rack and pinion steering
6-cylinder models
(525i, 5281, 5300
Two types of steering systems are used in E39 models. 6-
cylinder (525i, 5281, 530i) models are equipped with a steer-
ing rack system. V-8
(540i) models are equipped with a re-
circulating ball and nut steering gearbox.
Rack-and-pinion steering
Steering components in 6-cylinder models consist of a rack-
and-pinion type steering gear and connecting linltage to the
road wheels.
The steering linkage connects the rack-and-pinion unit
through tie rods to the steering knucltles. The tie rod ends al-
low the wheels to pivot and react to suspension travel.
Recirculating ball and nut steering
V-8 models
(540i)
I
Recirculating ball and nut steering
Recirculating ball and nut steering in V-8 models consists of a
steering box with integrated hydraulic control valve and con-
necting linkage to the road wheels.
Thesteering linkageconnects the steering gearbox through a
pitman arm to the wheels. An idler arm maintains correct toe
angle. The tie rod allow the wheels to pivot and react to sus-
pension travel.
E39 cars are equipped with power disc brakes with integral
antilock brakes (ABS). The parking bralte is a dual-drum sys-
tem integrated with the rear brake rotors.
Power assist is provided by a vacuum booster when the en-
gine is running. The brake pedal
pushrod is connected direct-
ly to the master cylinder, so failure of the vacuum booster
does not normally result in total
bralte failure.
Each disc bralte uses a caliper with a single hydraulic cylin-
der. Brake pads in the left front and right rear contain wear
sensors. When brake pads need replacement, the sensors il-
luminate a light on the dashboard.

Downloaded from www.Manualslib.com manuals search engine
Suspension, Steering and Brakes - General
WHEELS AND TIRES
Tire size is critical to the properoperation of the antilock brake
system and traction control system. Several differentstyles of
wheels in
15,16, and 17 inch diameters are available from an
authorized BMW dealer.
Rim and tire size applications are listed in the table below.
Rim and tire sizes table
ELECTRONIC BRAKE AND STABILITY
CONTROL SYSTEMS
Model
5251
5281
530i
540i (manual
transmission)
540i (automatic
transmission)
All
E39 vehicles are equipped with the Antilock Braking Sys-
tem
(ABS). Early production models featured ABS with Auto-
matic Stability
control (ABSIASC). Later models came
equipped with ABS and Dynamic Stability Control
(ABSIDSC). DSC builds upon the existing ABSIASC system
to provide electronic control of drive and braking systems to
insure vehicle stability.
This manual will refer to these systems as ABS. ASC or DSC
will be specified when necessary. ABS component replace-
ment is covered in
340 Brakes.
Standard
ABS applications are shown in the accompanying table
Rim size
16x7
15x7
16x7
17x8
16x7 Optional
Tire size
225160R-15
235145-1 7
225155-1 6
Rim size
17x8
Front 17
x 8 Rear 17 x 9
17 x 8
Front 17x8
Rear 17x9
Front 17 x 8
Rear 17 x 9 Tire
size
245145R-17
Front 235145-1 7
255140R-17
235145R-17
Front 235145-1 7
Rear
255140R-17
Front 235145-17
Rear 255140R-17

Downloaded from www.Manualslib.com manuals search engine
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

Downloaded from www.Manualslib.com manuals search engine
Suspension, Steering and Brakes - General
Front ride height specifications
(measurement
A)
E39 6-cylinder (5251,5281,530i) models
E39
V8 (540i) models
Wheel size
15 inch
16 inch
17 inch
18 inch
Maximum variation between sides: 10 mm (0.4 in)
Maximum deviation from specifications: 10 mm (0.4 in)
Standard
suspension
579 mm (22.8 in)
592 mm (23.3 in)
607 mm (23.9 in)
620 mm (24.4 in)
Wheel size
15 inch
16 inch
17 inch
18 inch Sports suspension
559
mm (22.0 in)
572 mm (22.5 in)
587 mm (23.1 in)
600 mm (23.6 in)
Maximum variation between sides: 10 mm (0.4 in)
Maximum deviation from specifications: 10 mm (0.4 in)
Standard
suspension
579 mm (22.8 in)
592
mm (23.3 in)
607 mm (23.9 in)
620 mm (24.4 in) Rough
road suspension
599
mm (23.6 in)
612 mm (24.1 in)
627 mm (24.7 in)
640 mm (25.2 in)
Sports suspension
559 mm (22.0 in)
572 mm (22.5 in)
587 mm (23.1 in)
600
mm (23.6 in)
M sports package
559 mm (22.0 in)
572 mm (22.5 in)
587 mm (23.1 in)
600 mm (23.6 in)
Rough road suspension 599 mm (23.6 in)
612
mm (24.1 in)
627
mm (24.7 in)
640
mm (25.2 in)
M sports package
562 mm (22.1 in)
575 mm (22.6 in)
590
mm (23.2 in)
603
mm (23.7 in)

Downloaded from www.Manualslib.com manuals search engine
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

Downloaded from www.Manualslib.com manuals search engine
31 0-2
I Front Suspension
This repair group covers the repair and replacement of com-
ponents that make up the front suspension of E39 cars.
Two different types of steering systems are used in the E39
series. 6-cylinder
(5251,5281 and 530i) models are equipped
with a rack and pinion type steering system mounted to an
aluminum subframe.
V-8 (540i) models use a steering gear-
box type system mounted to a steel subframe.
See
300 Suspension, Steering and Brakes-General for a
description of the front suspension and components, as well
as specifications for setting ride height.
CAUTION-
Some E39 models are equipped with aluminum suspen-
sion components. The foiiowing 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-
ties. Only use brushes with stainless steei bristles.
Do not expose to flying sparks from grinding/cutting op-
erations.
* Do not subject to steei welding splashes.
Do not expose to temperatures over 80°C (176°F).
even for short periods. Temperatures in painting faciii-
ties are not a problem.
Special tools
Special service tools are required for most of the work de-
scribed in this repair group. In addition to the tools depicted in
the illustrations, avariety of press tools are necessaryfor con-
trol arm bushing replacement. Read the procedures through
before beginning any job.
31 2 210 I < Strut nut socket
(Tool No. 31 2 210)