1998 BMW 540i Ac system

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Final Drive
Final drive, removing and installing
- Raise rear of car.
WARNING-
Make sure that the car is firmly supported on jack stands de-
signed for the purpose. Place the jaclc stands beneath struc-
tural chassis
~oints. Do not i lace iaclc stands under
( suspension barfs.
Remove exhaust system. See 180 Exhaust System.
Disconnect drive shaft from final drive. See
260 Driveshaft.
Remove drive axle CV joint bolts (arrows) at left and right
sides. Suspend drive axles from body using stiff wire.
4 Support final drive with BMW special tool 33 4 390.
* Remove front final drive mounting bolt.
Remove rear final drive mounting bolts
(2).
Carefully lower final drive unit.
- To install, use BMW special tool 33 4 390 to lift final drive into
place.
CA UTIOP&
The following sequence must be used when installing the fi-
nal drive to prevent torsion stress on the final drive during in-
Install mounting bolts and finger tighten only.
Remove final drive support.
Tighten both rear mounting bolts.
Tighten front mounting bolt.
NOTE-
Use new self-locking nuts.
- Check differential oil level. See Differential oil level, check-
ing.
- Remainder of installation is reverse of removal.

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Final Drive
Final drive input shaft seal, replacing
- Remove exhaust system. See 180 Exhaust System
- Remove drive shaft. See 260 Driveshaft.
< Lift out collar nut locking plate (arrow).
4 While counterholding drive flange with special BMW tool 23
23 0 020 0 020 loosen and remove collar nut.

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. .
Final Drive Final drive output shaft seals, replacing
- Remove exhaust system (if necessary). See 180 Exhaust
System.
Remove drive axle
CV joint bolts
axle from body using stiff wire. (arrows).
Suspend drive
4 Drive out final drive output flange using soft faced hammer.
4 Remove seal using BMW special tool 00 5 010 and 32 1 060
or equivalent.

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331-16
I Final Drive
Worlting at top of coil spring, press center cap down or pry
upward to remove. If pushed down, remove from inside coil
spring.
4 Worlting from underneath, position BMW special tool 33 2
301
between 2nd and 3rd spring coil from the bottom.
Make sure tool recess faces upward.
Worlting in cargo compartment, guide BMW special tool
33
2 304
from above and thread into special tool 33 2 301.
4 Worlting in cargo compartment, attach BMW special tools 33
2 302.33
2 303 and 33 2 305 to special tool 33 2 304.
- Use special tool 33 2 306 to compress spring.
Tighten until lower spring end lifts off spring seat on wheel
bearing carrier.
- Model with air springs: Loosen compressed air pipes at air
distribution assembly to release system pressure.
WARNING-
The vehicle will lower when tlie airpipes are loosened.
- Remove final drive. See Final drive, removing and install-
ing.

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General ........................... .34 0.2
Special Tools
....................... .34 0.2
E39 brake system
.................... .34 0.4
Electronic braking and stability control
.... .34 0.4
Troubleshooting
..................... .34 0.5
Warnings and cautions
................ .34 0.7
Bleeding Brakes ................... .34 0.8
Brakes, bleeding
..................... .34 0.9
Brake Pads, Calipers and Rotors ... .34 0.1 1
Braking system components .......... .34 0.11
Brake pads,
checking and replacing ..... .34 0.12
Brake rotors, removing and installing
.... .34 0.15
Master Cylinder .................. .34 0.16
Master cylinder, removing and installing
. .34 0.17
Brake Booster .................... .349 0.1
Brake booster check valve
............ .34 0.19
Brake booster, removing and installing
.. .34 0.20
Parking Brake .................... .34 0.22
Parking brake components
............ .34 0.22
Parking
brake, adjusting .............. .34 0.22
Parking bralte shoes, removing
and installing
....................... .34 0.23
Parking
brake cable, replacing ......... .34 0.24
ABS Component Replacement ..... 340-26
Wheel speed sensor. replacing
......... 340-26
ABS impulse wheel
.................. 340-27
DSC lateral acceleration or
rotational rate (yaw) sensor. replacing
... 340-27
DSC steering angle sensor.
removing and installing
............... 340-28
DSC precharge pump.
removing and installing (1998 models)
... 340-29
DSC pressure sensor
(1 999 - 2002 models) ................ 340-30
ABS /traction electronic control
module
(1 997 -1 998 models) .......... 340-31
ABS
/ DSC control module
(1 999
- 2002 models) ................ 340-31
ABS
/ traction control hydraulic unit.
removing and installing
............... 340-31

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This repair group covers brake service:
Brake pads, calipers, and disks
Master cylinder, bralte booster, and parking brake
ABS
1 ASC and ABS / DSC component replacement
ABS
1 ASC and ABS 1 DSC system descriptions are covered
in
300 Suspension, Steering and Brakes - General.
Special Tools
BMW requires the use of either the DIS or the MoDiC diag-
nostic tool to safely and completely bleed the
brak~ng and
traction control systems. Read all procedures through before
beginning a job.
< Parking bralte cable adjusting tool
(Tool No. BMW 34
1 030)
4 Brake piston expander
(Tool No. BMW 34
1 050)
4 Bralte caliper bolt tool (7 mrn Allen)
(Tool No. BMW 34
1 080)
34 I 000
34 1 090 < Steel wire brush
7 (Tool No. BMW 34 1 090)

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E39 brake system
BMW E39 models are equipped with vacuum power-assisted
four-wheel disc brakes with an integral
Antilock Brake System
(ABS). Single-piston calipers act on vented front and rear ro-
tors. A brake pad wear sensor for each axle indicates when
brake pads need replacement. The dual drum-type parking
brake system is integrated with the rear brake rotors.
Electronic braking and stability control
E39 models were introduced with Automatic Stability Control,
a computer controlled traction control system that uses the
AB5 system in conjunction with engine management controls
to control wheel spin during take-off and maintain vehicle sta-
bility while braking.
Added in the
1998 model year was Dynamic Stability Control
(DSC). This system implements wheel speed modulation
throughout all stages of driving. For example, DSC is able to
reduce understeer by applying differing amounts of braking
force to each wheel, or it can override the engine manage-
ment system during hard cornering.
A summary of distinguishing characteristics of the various
systems is shown in the table
E39 electronic braking and
stability control systems.
For ABS, ASC and DSC system and component descriptions,
see
300 Suspension, Steering and Brakes-General.
WARNING-
A car with electronic stability control is still subject to normal
physical laws. Avoid excessive speeds for the road conditions
encountered.
E39 electronic braking and stability control systems
Year (model)
manuf. up to 911998
(528i, 540i)
manuf. from 911999
(540i optional)*
From
911 999
(ail models) System
Automatic Stability Control (ASC) Identifiers
Electronic control module next to glove compartment
Hydraulic unit in right rear of engine compartment
No precharge pump
Dynamic Stability Control
(Bosch DSC
Ill v. 5.3)
Dynamic
Stabil~ty Control
(Bosch DSC
Ill v. 5.7) Electronic
control module next to glove compartment
Hydraulic unit in right rear of engine compartment
Precharge pump in left front of engine compartment, below steering
fluid reservoir
Separate rotational rate (yaw) and lateral acceleration sensors
Control
modulelhydraulic unit in right rear of engine compartment
No precharge pump
Combined rotational rate (yaw) and lateral acceleration sensors

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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.