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Driveshaft
Driveshaft problems and causes
Symptom Probable cause Corrective action
Vibration when starting off Center bearing rubber deteriorated. Inspect center bearing and rubber. Replace if necessary.
(forward or reverse)
Flex-disc damaged or worn.
Inspect flex-disc. Replace
if necessary.
Engine or transmission mounts
faulty. Inspect engine and transmission mounts. Align or
replace, if necessary.
Front centering guide worn, or driveshaft
Checic front centering guide and replace
if necessary.
mounting flanges out of round.
Check
runout of driveshaft flanges.
Universal joint worn or seized.
Check universal joint play and movement. Replace
driveshaft if necessary.
Driveshaft misaligned. Check driveshaft alignment.
Noise during onloff throttle Final
drive components worn or damaged
Remove final drive and repair. 331 Final Drive
or when engaging clutch. (excessive pinion-to-ring-gear clearance).
Drive axle or CV joint faulty.
Inspect drive axles and CV joints. Repair or replace as
necessary.
331 Final Drive
Vibration at 25 to
30 mph
Front centering guide worn, or driveshaft
Check front centering guide and replace if necessary.
(40 to 50
kmlh). mounting flanges out of round or damaged.
Check runout of driveshaft mounting flanges.
Universal joint worn or seized.
Check universal joint play and movement. Replace
driveshaft if necessary.
Flex-disc damaged or worn.
Inspect flex-disc. Replace if necessary.
Center bearing rubber deteriorated.
Inspect center bearing. Replace if necessary.
Misaligned installed position. Check driveshaft alignment.
Vibration, audible rumble Front centering guide worn, or driveshaft
Check front centering guide and replace
if necessary.
over
35 mph (60 kmlh). mounting flanges out of rouncl or damaged.
Check runout of driveshaft mounting flanges. - -
Mounting flange bolts loose or holes worn.
Remove driveshaft and check transmission output flange
and final drive input flange. Replace if necessary.
Driveshaft unbalanced. Check driveshaft for loose or missing balance weights.
Have driveshaft rebalanced or replace if necessary.
Universal ioint worn or seized.
Check universal ioint
~lav and movement. Reolace ' .. driveshaft if necessary.
Center bearing faulty.
Replace center bearing.
.
Final drive rubber mount faulty.
Inspect final drive rubber mount and repiace if necessary.
Driveshaft misaligned.
Check driveshaft alignment.
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Driveshaft, aligning
The alignment of the driveshaft does not normally need to be
checked unless the engineltransmission or the final drive
have been removed and installed. if ail other parts of the
driveshaft have been inspected and found to be okay, but
there is still noise or vibration, driveshaft alignment should be
checked.
There are two important driveshaft alignment checks. The
first is to make sure that the driveshaft runs straight from the
transmission to the final drive, without any variation from
side-
to-side caused by misalignment of the engineltransmission in
its mounts. Make a basic check by sighting along the
drive-
shaft from back to front. Any misalignment should be appar-
ent from the center bearing forward.
To adjust the side-to-side alignment, loosen transmission or
engine mounts to reposition them, then retighten mounts.
The driveshaft should be exactly centered in driveshaft tun-
nel.
The second important driveshaft alignment check is more
complicated. It checlts the amount the driveshaft is angled
vertically at the joints. This angle is
lknown as driveshaft
deflection.
In general, there should be little deflection in the driveshaft
between the engine, the center bearing, and the final drive.
Precise checks require the use of a large protractor or some
other means of measuring the angle of the engine and the fi-
nal drive and comparing these angles to the angle of the
. . driveshaft sections.
- To change the deflection angle, shims can be placed be-
tween the center bearing and the body or between the trans-
mission and its rear support. When using shims to change a
deflection angle, keep in mind that the angle of adjacent
joints will also change. Deflection angles should be as small
as
oossible.
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Driveshaft
- Road test vehicle to check for noise or vibration
CAUTION-
Do not reuse self-locking nuts. These nuts are designed to
be used only once.
Avoid stressing the flex-disc when torquing the bolts.
Do this by counterholding the bolts and turning the nuts
on the flange side.
Tightening torques
Alunlinum driveshaft to flex-disc
- MI2 (use coated washers)
90 Nm (66 ft-lb)
Driveshaft
CV joint to final drive flange
Mi0 (Tom bolt)
70 Nm (51 ft-lb)
M8 (compression nut) 32 Nm (24 ft-lb)
Flex-disc to transmission flange or driveshaft
MI0 (8.8 grade) 48 Nm (35 ft-lb)
MI 0 (1 0.9 grade) 60 Nm (44 ft-lb)
- Mi2 (8.8 grade)
81 Nm (60 ft-lb)
- MI2 (10.9 grade) I00 Nm (74 ft-lb)
MI4 140 Nm (103 ft-lb)
Transmission
crossmember
to transmission (ME) 21 Nm (15 ft-lb)
. to chassis (M10) 42 Nm (30 ft-lb)
NOTE-
Boltgrade is marked on the bolt head. When replacing bolts,
only use bolts of the same strength and hardness as the orig-
inals installed.
Flex-disc, replacing
- Checlc flex-disc between front section of driveshafl and trans-
mission output flange for craclts, tears, missing pieces, or
distortion. Check for worn bolt hole bores in flange.
- If flex-disc needs replacement, remove driveshafl as de-
scribed earlier.
- Unbolt flex-disc from driveshaft.
NOTE-
Removal andinstallation of the bolts may be made easier by
placing a large hose clamp around the flex-disc, and tighten-
ing the clamp slightly to compress the rubber.
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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.
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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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I Steerina and Wheel Alianment
Steering
system
Two types of steering gear are used in the E39 series models.
6-cylinder
(5251, 528i and 530i) models are equipped with
rack and pinion steering. The steering rack is mounted to
an aluminum subframe.
V-8
(540i) models are equipped with a recirculating ball
and nut steering gearbox mounted to a steel subframe.
At low speeds, maximum power assist is provided to ease
parking and city driving. At high speeds, assist is reduced to
ensure stability. The power steering system varies assist
based on engine speed.
Power boost for the steering is provided by an engine-driven
hydraulic pump. A hydraulic control valve is used to control
boost pressure.
The steering wheel connects to the steering gear via an ad-
justable steering column which incorporates a rubber cou-
pling ("guibo") to dampen vibration and noise.
Power steering fluid is supplied from the fluid
reservoir to the
pump and to the steering gear via rubberlmetal hoses.
The return line from the steering gear to the
reservoir loops
into the airstream in front of the radiator and connects to the
steering fluid cooler. The fluid cooler is attached to a cassette
which also includes cooling coils for engine oil, transmission
fluid and AIC condenser.
The steering gear requires no maintenance other than align-
ment and periodic inspection for worn components. Inspect
rubber rack boots
(rack and pinion system) and tie-rod end
boots periodically for tears or damage. Replace
if necessary.
-
NOTE-
The airbag system is traditionally referred to as Supplemen-
tal Restraint System (SRS). The
BMW versfon of SRS used
m the E39 models is known as the Multiple Restraint System - (MRS). - -
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Brakes
Troubleshooting
Brake performance is mainly affected by three things:
Q Level and condition of brake fluid
Ability of bralte system to create and maintain pressure
Condition of friction components
Air in bralte fluid will
make the brake pedal feel spongy during
braking
orwill increase the bralte pedal force required to stop.
Fluid contaminated by moisture or dirt can corrode the sys-
tem. lnspect the brake fluid inside the reservoir. If it is dirty or
murky, or is more then two years old, replace fluid.
To
check the function of the master cylinder hold the bralte
pedal down hard with the engine running. If the pedal slowly
falls to the floor, either the master cylinder is leaking internal-
ly, or fluid is leaking externally.
lnspect the rotors for glazing, discoloration and scoring.
Steering wheel vibration while braking at speed is often
caused by warped rotors, but can also be caused by worn
suspension components.
When troubleshooting, keep in mind that tire inflation, wear
and temperature can all have an affect on braking. See
300
Suspension, Steering and Brakes-General for additional
suspension and brake system troubleshooting.
The table Brake system troubleshooting lists symptoms of
brake problems, probable causes, and suggested corrective
actions. Unless noted otherwise, relevant repairs are de-
scribed later in this repair group.
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340-28
Brakes
- Remove sensor mounting screws. Lift sensor away from
bracket.
- Installation is reverse of removal.
CAUTION-
Be sure to tighten the DSC acceleration sensor(s) and
mounting bracket, if applicable, to specified torques. The
sensor
is vibration sensitive and subject to cause DSC
malfunctions if installed improperly.
a After replacing the sensor, perform sensor adjustment
using either DIS or
MoDiC under Service Functions
menu.
Tightening
torques
Lateral acceleration I rotational rate sensor 8 Nm (6 R-ib)
to bracket
Sensor bracket to body
8 Nm (6 ft-lb)
DSC steering angle sensor, removing and
installing
4 Remove lower dash panel mounting fasteners (A) and (5).
- Remove steering column lower trim panel. See 320 Steering
and Wheel Alignment.
Remove steering shaft clamping bolt (arrow).
Disconnect sensor wiring harness connector.