brake BMW 740I 1998 Owner's Manual

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RepairsIndexOverview Controls Car care Technology Data
Antilock Brake System (ABS)The conceptABS enhances active safety by helping
to prevent the wheels from locking dur-
ing brake applications. The reason:
Locked wheels are dangerous. When
the front wheels slide, the driver loses
steering control over the vehicle. Trac-
tion loss at the rear wheels can cause
the rear end to break into an uncon-
trolled skid.
The system can achieve the shortest
braking distances possible under most
conditions (on straights and in curves,
on asphalt, ice, wet road surfaces, etc.).
ABS is designed to meet two essential
requirements during every brake appli-
cation:
>To help provide vehicle stability
>To help maintain steering control and
maneuverability – on all types of road
surfaces (asphalt, concrete, mud, wet
pavement, snow, ice).
Braking with ABSThe system becomes operative once
the vehicle exceeds a speed of approx.
6 mph (10 km/h). The ABS is deactivated
whenever the vehicle's speed drops
back below approx. 4 mph (6 km/h). This
means that the wheels can lock in the fi-
nal phase of a panic stop – a factor of no
significance in actual use.
If you are in a situation which requires
full braking, you will exploit the full bene-
fits of the ABS system if you apply maxi-
mum brake pressure ("panic stop").
Since the vehicle maintains steering re-
sponsiveness, you can avoid possible
obstacles with a minimum of steering ef-
fort, despite the full brake application.
The ABS system closed-loop control cir-
cuit cycles in fractions of a second.
A pulsation at the brake pedal indicates
to the driver that ABS is active, that is,
that the vehicle is within its maximum
braking range. In addition, a pulsation – a
result of the control function cycles – in-
dicates to the driver that vehicle speed
should be reduced to adapt to road sur-
face conditions when there is reduced
traction and grip between tires and road
surface (slippery road surface).
Always depress the brake pedal with
constant pressure. Keep the brake pedal
down. Do not pump the brakes.In driving conditions where there is a
loose upper surface together with a
subsurface which provides better trac-
tion (on gravel or snow, for instance), or
with snow chains, the braking distance
may also be longer than when the
wheels are locked. However, ABS con-
tinues to provide enhanced vehicle sta-
bility and steering response under
these conditions.
Information for your safetyNot even ABS can suspend the laws of
physics. ABS alone cannot prevent ac-
cidents when the brakes are applied
without an adequate safety interval be-
tween vehicles, if the car is driven at an
excessive rate of speed in curves, or if
aquaplaning occurs. Responsibility for
these types of situations remains in the
hands (and at the feet) of the driver. You
should never allow the added safety of
ABS to lull you into a false sense of se-
curity, or mislead you into taking in-
creased risks that could affect your own
safety and that of others.
Do not make any modifications to
the ABS system.
Service procedures on ABS are to be
performed by authorized technicians
only.<

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Antilock Brake System (ABS) Disc brakesIn the event of a fault
If the ABS warning lamp in the
instrument cluster comes on, re-
fer to page 21. The brake sys-
tem then reverts to conventional
operation as on vehicles without
ABS. However, have the brake
system checked by your BMW center
as soon as possible. To prevent unde-
tected defects and cumulative faults
from adversely affecting the brake sys-
tem, refer any problems to your autho-
rized BMW center at the earliest oppor-
tunity.
Disc brakes furnish optimum decelera-
tion and braking control and greater
fade resistance under heavy use.
When the vehicle is driven only occa-
sionally, during extended periods when
the vehicle is not used at all, and in op-
erating conditions where brake applica-
tions are less frequent, there is an in-
creased tendency for corrosion of the
rotors and accumulation of contamina-
tion on the brake pads. This occurs be-
cause the minimal pressure which must
be exerted by the pads to clean the ro-
tors by brake applications is not
reached.
If the brake rotors are corroded, they
will tend to respond to braking with a
pulsating effect which even extended
application will fail to cure.
We recommend the use of original
BMW brake pads and compo-
nents, otherwise driving safety can be
impaired.<

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RepairsIndexOverview Controls Car care Technology Data
Disc brakesDriving notesWhile driving in wet conditions and in
heavy rain, it is a good idea to apply
light pressure to the brake pedal every
few miles. Watch traffic conditions to
ensure that this maneuver does not en-
danger other road users. The heat gen-
erated in this braking process helps dry
the brake pads and rotors.
Maximum braking force is obtained
while the wheels continue to rotate,
peaking when the wheels remain on the
verge of locking without actually doing
so. ABS maintains this state automati-
cally. If the ABS fails, you should revert
to the staggered braking technique de-
scribed below (refer to page 129).
Extended or steep mountain descents
do not necessarily have to lead to re-
duced braking efficiency; downshift to a
gear in which only minimal periodic
brake applications are required - move
the selector lever to the appropriate
lower range.
You can continue to increase the brak-
ing effect of the engine by selecting a
lower gear - you can select transmis-
sion ranges as low as position 2 for ex-
treme conditions.Should engine braking prove inade-
quate, you should still avoid extended,
continuous braking. Instead of main-
taining low to moderate pressure over
an extended period of time, you should
decelerate the vehicle by applying more
substantial force on the pedal (watch
for following traffic!) and then pausing
before repeating the application. This
staggered braking technique allows the
brakes to cool in the intervals between
active braking phases, preventing over-
heating and ensuring that full braking
capacity remains available at all times.
Do not coast with the transmission
selector lever in neutral. Do not
drive with the engine shut off. The en-
gine provides no braking effect when
the transmission is in neutral, and there
is no power-assist for braking or steer-
ing when the engine is shut off.
Never allow floor mats, carpets or any
other objects to protrude into the area
around the accelerator and brake ped-
als and obstruct their movement.<
Dynamic Brake Control (DBC)
*
If you apply the brakes rapidly, this sys-
tem automatically produces the maxi-
mum braking force boost and thus
helps to achieve the shortest possible
braking distance during "panic stops."
All of the benefits of the ABS system
are exploited under these circum-
stances.
Do not reduce the pressure on the
brake pedal for the duration of the
brake application. When the brake
pedal is released, the DBC is deacti-
vated.
In the event of a malfunction, the
warning lamp comes on with a
yellow light. Conventional brak-
ing efficiency is available with-
out limitations.
Have the system checked and
repaired at your BMW center as soon
as possible.
For "Information for your safety"
covering the ABS system, refer to
page 125. This information also gener-
ally applies for DBC.<

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Brake system Winter operationBrake fluid level
The warning lamp for the brake
hydraulic system comes on or
the message "Check Brake
Fluid" appears in the Check
Control:
The brake fluid level is too low in the
reservoir. Refer to page 147.
If the brake fluid level is too low and
brake pedal travel has become notice-
ably longer, there may be a defect in
one of the brake system's hydraulic cir-
cuits.
The remaining circuit continues to pro-
vide adequate brake-system perfor-
mance.
Proceed to the nearest authorized
BMW center. Higher brake appli-
cation pressure may be necessary un-
der these conditions, and brake pedal
travel may be significantly longer.
Please remember to adapt your driving
style accordingly.<
The warning lamp also comes on with
the "Check Brake Pads" message in the
Check Control.
Brake padsThe message "Check Brake Pads" ap-
pears in the Check Control:
The brake pads have reached their min-
imum pad thickness. Proceed to the
nearest authorized BMW center as
soon as possible to have the pads re-
placed.
We recommend the use of original
BMW brake pads and compo-
nents, otherwise driving safety can be
impaired.<
The onset of winter is often accompa-
nied by rapid changes in weather. Ad-
aptations in driving style should be ac-
companied by preparations on the
vehicle itself to ensure that your vehicle
operation through the winter remains
safe and trouble-free.CoolantBe sure that the coolant mixture is kept
at the year-round ratio of 50:50 (water
and antifreeze/corrosion protection).
This mixture provides protection
against freezing down to approx. –347
(–376). Replace the coolant every four
years.LocksBMW door lock deicer can be used to
free the locks if they are frozen. This
deicer also contains lubricant.
After using deicer, treatment with BMW
lock barrel grease is recommended.

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RepairsIndexOverview Controls Car care Technology Data
Winter operationRubber seals and componentsIn order to prevent the weather-strip-
ping from freezing, apply rubber treat-
ment or a silicone spray to the seals on
the doors, hood and luggage compart-
ment lid.
A full range of car care products is
available from your BMW center.< Snow chainsBMW snow chains
* can be fitted on
both summer and winter tires in re-
sponse to severe winter road condi-
tions. Mount them in pairs on the rear
wheels only, and be sure to comply with
the manufacturer's safety instructions.
Do not exceed a maximum speed of
30 mph (50 km/h). In this situation
(snow chains mounted), deactivate the
ASC+T or DSC
*. Refer to page 92.
Starting offWhen starting off in deep snow or when
rocking the car to free it, we recom-
mend that you switch the ASC+T or
DSC
* off. Refer to page 92.
Driving on low-traction road
surfacesUse smooth, gentle pressure to control
the accelerator pedal. Avoid excessive
engine speeds and shift to the next
higher gear at an early point. Adapt
your speed and driving style when ap-
proaching grades. Maintain an ade-
quate distance between yourself and
the car ahead.BrakesWinter road conditions substantially re-
duce the amount of traction available
between the tires and the road surface;
the resulting increases in braking dis-
tance are considerable and should be
continually borne in mind.
ABS is intended to prevent the wheels
from locking during brake applications,
thus helping to maintain vehicle stability
and steering response. If the ABS does not respond in a critical
braking situation and the wheels lock:
Reduce the pressure on the brake
pedal until the wheels just start to roll
again while still maintaining enough
force to continue braking.
Following that, increase pedal pressure
again. Reduce the pressure as the
wheels lock, then reapply pressure, etc.
This type of staggered braking will re-
duce the braking distance, and the ve-
hicle still remains responsive to steer-
ing.
You can then attempt to steer around
hazards after you have reduced pres-
sure on the brake pedal.
Do not shift down on slick road
surfaces. Doing so could cause
the rear wheels to lose traction and
skid, which could result in the loss of
vehicle control.<

130n
Winter operation Power steering Level control system
*
Skid controlRelease the accelerator pedal. Coun-
tersteer carefully and attempt to regain
control of the vehicle.ParkingPlace the selector lever in position P
(Park). Engage the parking brake when
parking on hills and inclined surfaces. In
order to prevent the parking brake lin-
ings from locking in the drum due to
frost or corrosion, dry them by gently
applying the parking brake as the vehi-
cle is coming to a stop. Make sure that
following traffic is not endangered.
The brake lamps do not come on
when the parking brake is ap-
plied.<
High steering effort:
Check the fluid level. Refer to
page 148.
High steering effort during sudden tran-
sitions:
Consult your authorized BMW center
immediately for an inspection.Servotronic special
*
If steering becomes lighter as speed in-
creases:
Malfunction in the electronic control
system. Have your BMW center inspect
this system as soon as possible.
If the power steering fails, in-
creased effort will be required to
steer the vehicle.<
If the message "LEVEL CONTROL IN-
ACTIVE" appears in the Check Control,
there is a malfunction in the level con-
trol system.
Stop and inspect the vehicle. If it is
riding significantly lower in the rear
than in the front, or if it is sitting at an
incline (left rear compared to right rear),
consult the nearest authorized BMW
center. Drive with appropriate caution
in the meantime. The vehicle has re-
duced ground clearance or driving
comfort is noticeably reduced.
Even if the attitude of the vehicle is nor-
mal, you should consult the nearest au-
thorized BMW center if the warning
lamp indicates a system fault.

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RepairsIndexOverview Controls Car care Technology Data
Engine compartment – BMW 740i/L1 Brake fluid reservoir147
2 Power steering fluid reservoir/
Level control system148
3 Auxiliary terminal for jump
starting179
4 Engine oil dipstick143
5 Engine oil filler neck143
6 Coolant expansion tank146
7 Reservoir for headlamp
and windshield washer system142
8 Fuse box176

141n
RepairsIndexOverview Controls Car care Technology Data
Engine compartment – BMW 750iL1 Brake fluid reservoir147
2 Power steering fluid reservoir/
Level control system148
3 Auxiliary terminal for jump
starting179
4 Engine oil filler neck143
5 Coolant expansion tank146
6 Engine oil dipstick143
7 Reservoir for headlamp
and windshield washer system142
8 Fuse box176

147n
RepairsIndexOverview Controls Car care Technology Data
Brake fluidBrake fluid level
Brake hydraulic system warning
lamp comes on, "Check brake
fluid" appears in the Check Con-
trol display: The brake fluid level
is too low in the reservoir.
Fill up to upper mark ("MAX" level visi-
ble through the transparent reservoir).
Any BMW center can provide you with
information on factory-approved brake
fluids (DOT 4).
Brake fluid loss results in extended
pedal travel. Refer to the information on
page 128.
380de080
Brake fluid is hygroscopic, that is,
it absorbs moisture from the air
over time.
In order to ensure the operating safety
of the brake system, have the brake
fluid changed every two years by your
BMW center. Refer also to the Service
Warranty Information Booklet (US mod-
els) or to the Warranty and Service
Guide Booklet (Canadian models).
Brake fluid is toxic and damages the ve-
hicle's paint. Always store brake fluid in
the original containers. Keep the con-
tainers tightly closed and out of reach
of children. Do not spill brake fluid. Do
not fill beyond the "MAX" level in the
reservoir. The brake fluid could ignite
upon contact with hot engine parts and
cause serious burns.<
Comply with the applicable envi-
ronmental laws regulating the dis-
posal of brake fluid.<

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Caring for your carWashing your carYou can have your new BMW washed
in an automatic car wash. Car wash
systems that do not employ brushes are
preferable.
Wipe away tough dirt and loosen and
remove dead insects before washing
the car.
To prevent spots, avoid washing when
the hood is still warm, or immediately
after and during exposure to strong
sunlight.
When using an automatic car wash, be
sure that:
>The car wash system is suited for the
dimensions of your vehicle
>No damage will occur on vehicles
with attached body accessories (such
as spoilers or antennas). If you are
uncertain, consult the manager of the
car wash
>The wheels and tires of your vehicle
cannot be damaged by the convey-
ance devices of the car wash system
>The vehicle is cleaned with minimum
brush pressure, and that ample water
is available for washing and rinsing.Vehicles with rain sensor
*:
Clean the windshield regularly. Wax
from automatic car washes or insects,
for example, can cause malfunctions in
the function of the rain sensor.
Turn the rain sensor off in auto-
matic car washes. If you do not,
damage may occur if the wipers switch
on unintentionally.<
Parts of the car which are inaccessible
to the automatic washer - such as door
sills, door and hood edges, etc. -
should be cleaned by hand.
In the winter months, it is especially im-
portant to ensure that the car is washed
on a regular basis. Large quantities of
dirt and road salt are difficult to remove,
and they also cause damage to the ve-
hicle.
If spray wands or high-pressure
washers are used, be sure to
maintain an adequate distance between
the spray source and the vehicle's sur-
face.
Inadequate distance and excessive
pressure can damage or weaken the
finish, making it more susceptible to
subsequent attack. In addition, mois-
ture could penetrate to vehicle compo-
nents, leading to long-term damage.<
When cleaning the headlamps,
please observe the following:
>Do not clean by wiping with a dry
cloth (scratches). Never use abra-
sives or strong solvents to clean the
covers
>Remove dirt and contamination
(such as insects) by soaking with
BMW Car Shampoo and then rinsing
with plenty of water
>Always use a deicer spray to remove
accumulated ice and snow – never
use a scraper.<
After washing the car, apply the
brakes briefly to dry them. Braking
efficiency might otherwise be reduced
by the moisture, and the brake rotors
could also be corroded.<