1997 BMW 525i brake

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4 Remove plastic caps from caliper mounting bolts (arrows).
Use BMW special tool 34 1 080 (7 mm Alien wrench) to re-
move caliper mounting bolts. Remove caliper from pad
carri-
e r.
NOTE-
If there is a ridge on brake rotor edge, press caliper pistons
back into caliper before removing caliper.
- Check brake rotor thickness. Inspect for rust or damage. if
necessary replace or machine brake rotors as described lat-
er. Bralte rotor specifications are given in table below.
Spread bralte pads using BMW special tool
34 1 050 or
equivalent. Remove brake pads.
CA UTIOG
Pressing caliperpistons in may cause brake fluid reservoir to
overflow. To prevent this, use a clean syringe to first remove
some fluid from reservoir.
NOTE-
Inner brake pad lias a spring to locate it in the caliper piston.
4 Carefully pry pad wear sensor from brake pad
- Check caliper dust boots for damage and replace if neces-
sary.
- Clean contact surfaces between caliper and caliper carrier.
C"..., I,.. P,hi..,,,.r.. mm-*ii Ai"i,li "1.i"~"d

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340-1 4
Brakes
4 Apply a thin coating of BMW anti-squeal compound to caliper
contact face
(arrow).
Do not apply grease to brake pad backing plate.
Right Left
CAUTION-
Do not let calliper rubber dust sleeve come in contact with
anti-squeal compound. The rubber will swell and deteriorate.
4 Apply a thin coating of BMW anti-squeal compound to bralte
pad rests (arrows) on pad carrier.
4 When installing directional brake pads, install the marked
pads as shown.
NOTE-
BMW-supplied (OEM) front brake pads may be marked as di-
rectionalpads. Aftermarket brands are generally not labeled
as directional. When installing directional pads, be sure to in-
stall them as indicated in the illustration.
- Where applicable, insert brake pad wear sensor into cutout
in new pad. Push sensor into pad cutout until it locks into
place.
- -
- NOTE-
If brake lining indicator light illuminatedprior to brake pad re-
placement, replace wear sensor.
- Route pad wear sensor wiring through caliper opening and
under bleeder dust cap.

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340-1 5
Brakes
- Remainder of installation is reverse of removal.
- Clean brake caliper mounting bolts (7 mm Allen). Replace
ones which are not in perfect condition. Do not grease.
Top up brake fluid to MAX marking.
- Before driving car, pump bralte pedal several times so that
brake pads contact brake rotors.
Check that brake fluid level is correct. Top up if necessary.
Hold ignition key for at least
30 seconds in accessory po-
sition without starting engine. This clears any fault codes in
memory and turns off brake pad warning light.
Tightening torques Brake caliper to pad carrier
(7 mm Allen)
Front caliper
30 Nm (22 It-lb)
- Rear caliper 28 Nm (21 It-lb)
Road wheel to hub
120i 10 Nm (89i7 ft-lb)
Brake rotors, removing and installing
- Raise car and remove wheels
WARNING-
Male sure that the car is firmly supported on jack stands de-
signed for the purpose. Place jack stands beneath structural
chassis points. Do not place jack stands under suspension
parts.
Remove brake caliper carrier bolts (arrows). Suspend brake
caliper from chassis using stiff wire.
NOTE-
Hydraulic brake line remains connected.
4 Remove bralte rotor mounting screw (arrow) and remove ro-
tor.
- Inspect rotor for cracks, signs of overheating and scoring.
- Minimum allowable thickness (MIN TH) is stamped on rotor
hub. Measure rotor braking surface with a micrometer at
eight to ten different points and use the smallest measure-
ment. Compare to specifications in table below.
- If rotor does not pass minimum thickness requirements or is
damaged, replace rotor.

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1 Brakes
Max. machine limit per
friction ring side 0.8 mm (0.03
in) I
Brake rotor reconditioning specifications
Model
Replace
braite rotors in pairs
Bralre rotor sizes
Clean rotor with brake cleaner before installing.
Front
Model
6-cylinder
models (5251,
5281, 530i)
V-8 models (540i)
* When installing new rear brake rotors, adjust pariting brake
as described later, in Parking brake, adjusting. Rear
Vented rotor wear limit (min. thickness)
Tightening torques
Braite rotor to hub 16 Nm (12 ft-lb)
6-cylinder models
(525i, 5281, 530i)
- V-8 models (540i)
Front
296 mm (1 1.65 in)
324 mm (12.76 in)
Front bralte pad
carrler to steering ltnucitle 110 Nm (81 ft-lb)
Rear
298 mm (1 1.73 in)
Rear
brake pad carrier to wheel bearing carrier 65 Nm (48 ft-lb)
20.4
mm (0.80 in)
28.4 mm (1.12 in)
Road wheel to hub
120ilONm
(89 -t 7 it-lb)
18.4 mm (0.72 in)
The brake master cylinder is mounted to the front of the vacu-
um booster on the driverside bullthead.
-
CAUTION-
All E39 vehicles soldin the USA are equipped with Antilock
Braling System (ABS) and either Automatic Stability Control
(ASC) or Dynamic Stability Control (DSC).
In order for the
braling and stability controls to work properk if the brake
master cylinder is replaced, make sure that the brake system
is bled
by an authorized BMW dealer or other qualified repair
facility
using the BMW Service Tester. See Brake Bleeding
earlier
in this group.

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Brakes
Master cylinder, removing and installing
CAUTlOI\C
Brake fluid is highly corrosive and dangerous to the environ-
ment. Dispose of it properly.
4 Remove left side interior ventilation microfilter housing:
Remove upper cover and microfilter locking clip
(A).
- Release locking clamp (B), and rotate air tube in direction
of arrow to remove.
Disconnect wiring harness from hood switch
(C).
Release filter body mounting clamp (D) and remove lower
microfilter housing.
4 Remove side trim panel from left rear of engine compartment
by releasing clips
(arrows).
4 Disconnect bralte fluid level sensor connector (A) from fluid
reservoir. Remove reservoir cap.
. Using a clean syringe, empty bralte fluid reservoir.
Where applicable, disconnect hydraulic clutch system sup-
ply line from fluid reservoir duct
(5). Keep supply line sup-
ported and above clutch master cylinder to prevent air
bubbles from reaching clutch hydraulic system.
Where applicable, disconnect DSC system precharge
pump supply line from fluid reservoir duct
(C). Secure sup-
ply line in vertical position to prevent fluid loss.
Plug open brake fluid lines and ducts to prevent fluid leak-
age or contamination.
- Remove brake fluid reservoir by tilting sideways.

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.- -
Brakes
Disconnect master cylinder brake lines (A)
Plug open brake lines to prevent contamination.
Remove master cylinder mounting nuts
(6) and remove
cylinder.
NOTE-
It may be necessary to remove the brake booster with master
cylinder attached due to limited access.
Bralce master cylin-
dercan then be removed from booster. See Brake booster,
removing and installing later
in this repair group.
- During reinstallation, make sure all nuts, fluid couplings,
thread bores, and mating surfaces are clean.
- Mount master cylinder to bralte booster using new sealing O-
ring and new self-locking nuts.
CAUTIOI\C
* Be sure to align master cylinderpushrod and booster
pushrod.
* Do not over-torque master cylinder mounting nuts. This
could damage the brake booster and prevent proper
vacuum build-up.
Tightening torque Brake master cylinder to brake booster
26 Nm (19 ft-lb)
- Connect bralte fluid lines to master cylinder.
Tightening torque Brake fluid line to master cylinder
18 Nm (13 ft-lb)
- Carefully reinstall fluid reservoir using new sealing grommets.
- Reconnect precharge pump fluid supply hose, if applicable. -
- Reconnect hydraulic clutch fluid supply hose, if applicable.
- Remainder of installation is reverse of removal.
Top up with fresh brake fluid.
Bleed entire brake system as described earlier

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Brakes
The brake booster is mounted to the bulkhead on driver's side
of the engine compartment, directly behind the brake master
cylinder. Intake manifold vacuum acts on a large diaphragm
in the brake booster to reduce brake pedal effort.
Brake booster check valve
The checlc valve in the bralte booster vacuum line prevents
contamination from engine backfires and other sources from
entering the bralte booster.
Location of
check valve varies, depending on year and mod-
el.
4 6-cylinder models (528i):
1. Intake manifold
2 Hose clamp
3. Vacuum line
4. Upper hose bracket
5. Grommet 6. From 911998: Check valve in grommet in booster.
Remove left ventilation filter housing for access.
7. To 911 998: Check valve in vacuum hose. Remove left
ventilation filter housing, peel back trim rubber below
housing and
unclip upper hose brackets to access hose
clamps and valve.
8. Lower hose
bracket
9. Brake master cylinder
10. Brake booster
< 6-cylinder models (525i, 530i): Remove left ventilation filter
housing to access
checlc valve.
1. Vacuum hose
2. Hose clamp
3. Hose bracket
4. Check valve in grommet in booster
5.
Braite master cylinder
6. Grommet
7. Brake booster
4 V-8 models (540i) to 911998: Check valve (arrow) in vacuum
line behind left cylinder head.
- V-8 models (540i) from 911998: Checkvalve in brake booster.
Remove left ventilation filter housing to access valve.

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Brakes
- Pump brake pedal a few times to reduce vacuum in brake
booster. This makes removal of
check valve easier.
- Remove or loosen hose clamp(s) at check valve.
- Disconnect hoses. Remove valve to test or replace.
NOTE-
If valve is pressed into grommet in vacuum booster, pry it out
carefully.
- Reinstall valve using new hose clamps
NOTE-
Install the valve so that the molded arrow is pointing toward
the intake manifold.
Brake booster, removing and installing
CAUTIO&
All E39 vehicles sold in the USA are equipped with Antiloclc
Braking System (ABS) and either Automatic Stability Control
(ASC) or Dynamic Stability Control (DSC). In order for the
bralchg and stability controls to work properk if brake fluid
lines are disconnected and reconnected,
male sure that the
brake system is bled by an authorized BMW dealer or other
qualified repair facility using the BMW Service Tester: See
Brake Bleeding earlier in this group.
- Disconnect negative (-) cable from battery.
I CAUTION- I
Prior to disconnecting the battery read the battery discon-
nection cautions given in
001 General Cautions and
I Warnings. I
- Remove bralte master cylinder as described earlier.
- Disconnect engine vacuum hose from bralte booster.