BRAKES
Brakes - Repair Instructions - 325i, 325xi, 330i, 330xi, 328i, 328xi, 335i and 335xi
00 BRAKE TESTING AND BLEEDING
34 00 ... GENERAL INFORMATION
The brake system is one of the most important safety systems on any motor vehicle. It is therefore essential to
act with utmost care when working on the brake system and to follow the instructions below.
General:
Ensure cleanliness and only use rags which do not lose lint.
Wash away or vacuum up brake dust, do not clear it away using compressed air. This dust is a health
hazard.
Do not under any circumstances allow any oil or grease to get into the brake system. This would result in
a complete malfunction of the brake system.
When cleaning brake components with brake cleaner, do not allow brake cleaner to get into in the brake
system.
Even the most minute traces of brake cleaner must be avoided.
Brake fluid:
Replace brake fluid at least every two years.
Never reuse drained brake fluid.
Always use BMW-approved brake fluid, refer to BMW Service Operating Fluids .
Dispose of brake fluid in approved appliances only.
Do not allow brake fluid to drain into drain pipes, into the outside environment or into unsuitable
facilities. This would create the risk of groundwater contamination since brake fluid is classed as a fluid
that is hazardous to water.
Do not allow brake fluid to come into contact with paintwork as this will destroy the paint.
Brake fluid must not be allowed to remain on bare skin too long in order to avoid skin problems. Wash
skin coated with brake fluid with water and soap.
If brake fluid makes contact with eyes, immediately flush with large quantity of clean water and visit eye
doctor.
Wheel brakes:
Brake pads:
Brake pads must be replaced when the Warning Threshold Of The Brake Pad Wear Indicator is
reached.
2008 BMW 328xi
BRAKES Brakes - Repair Instructions - 325i, 325xi, 330i, 330xi, 328i, 328xi, 335i and 335xi
2008 BMW 328xi
BRAKES Brakes - Repair Instructions - 325i, 325xi, 330i, 330xi, 328i, 328xi, 335i and 335xi
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Brake pads must always be replaced on both sides of any axle.
The friction surfaces of the brake pads must not come into contact with oil or grease. The brake pads must
be replaced if they are fouled by such substances.
In the case of rotation-dependent brake pads, make sure the arrow marking points in the direction of
rotation of the brake disk for when the vehicle is moving forward. Brake pads with left/right markings
must be fitted on the relevant side of the vehicle.
One-sided angled areas on the brake pads must be located on the disk contact side of the brake caliper for
when the vehicle is moving forward.
Brake discs:
Brake disks must not be scored or cracked. Furthermore, Minimum Brake Disk Thickness , disk runout,
parallelism and surface roughness of the friction surfaces must not exceed or drop below the permitted
values.
Always strip preservative off new parts before installation. With the rear brake discs, also strip
preservative off brake drum on parking brake.
Always strip preservative off new parts before installation.
Brake calipers:
Only approved pastes on the basis of glycol must be used for repairs on brake calipers.
All moving parts on the brake caliper must move freely: note grease specifications.
Use only BMW-approved lubricants to grease caliper guides (refer to BMW Service Operating Fluids ).
Brake lines, brake hoses:
Brake lines and brake hoses must be correctly routed and must not abut with body or components in a
way which would cause chafing.
To prevent damage, release and tighten brake line couplings with a special brake line wrench only.
The system must be bled each time any brake lines have been detached.
All connection points must be checked for leaks.
Only tighten down brake hoses on the front axle when wheels are in straight-ahead position.
Close off open connections of brake lines and individual components to prevent dirt from getting into the
brake system.
When tightening down brake line couplings, observe tightening torque refer to 34 32 1AZ in 34 32
BRAKE LINES .
Wheel-slip control system:
2008 BMW 328xi
BRAKES Brakes - Repair Instructions - 325i, 325xi, 330i, 330xi, 328i, 328xi, 335i and 335xi
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The wheel-slip control system is essentially maintenance-free; however the following must be observed:
When carrying out welding work with electric welding equipment, be sure to disconnect the plug from
the electronic control unit (ignition turned off).
During painting work, the control unit may be subjected for brief periods to loads of max. 95°C and for
long periods (approx. 2 hours) to loads of max. 85°C.
Terminals must be completely tight on end poles of battery.
Brake lines on hydraulic unit must not be swapped over: if applicable, mark them prior to disassembly.
On completion of repair work, carry out swap-over test with the DIS diagnosis system.
34 00 ... GENERAL INFORMATION ON BRAKING IN NEW BRAKE DISCS / BRAKE PADS
34 00 ... TESTING AWD VEHICLES ON DYNAMIC BRAKE AND POWER ANALYZERS (E30, E34,
E46, E53, E83, E60, E61, E90, E91, E92)
In order to test AWD vehicles on dynamic brake analyzers, it is essential to follow various measures in
accordance with the special instructions in Appendices 1 to 5 for the vehicles in question:
1. E30 AWD
2. E34 AWD
3. E46 AWD
4. E53 X5
5. E83 X3
IMPORTANT: After completing work:
Carry out function check on brake analyzer (test stand) ensure that the
brakes complies with legal requirement
Carry out test braking while driving at low speed; the effectiveness of the
brakes may be reduced during the initial braking operations.
Exaggerated drastic and continuous braking operations faster braking in
are not permitted.
Advise the customer not to perform any wilful drastic braking in the first
200 km after brake replacement.
Attach mirror tag to interior rearview mirror.
NOTE: Running AWD vehicles on dynamic brake analyzers is governed by different
instructions, depending on the vehicle model.
IMPORTANT: Power measurements on single-axle roller dynamometers are generally not
permitted as total failure of the transfer case cannot be ruled out during such
measurements.
2008 BMW 328xi
BRAKES Brakes - Repair Instructions - 325i, 325xi, 330i, 330xi, 328i, 328xi, 335i and 335xi
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6. E60 / E61 AWD
7. E90/E91/E92 AWD
34 00 009 CHECKING BRAKES ON TEST STAND
N ecessary preliminary tasks:
Check tires for damage
Check tyre treads
Check tyre pressure
The brakes must be at normal operating temperature. To do so, gently warm up the brake disks and brake drums
while dry by braking the vehicle several times.
Fig. 1: Identifying Brakes Test Stand
Courtesy of BMW OF NORTH AMERICA, INC.
You must follow without fail the guidelines contained in the operating instructions of the relevant test stand
manufacturer.
Failure to do so may result in damage to the vehicle and the system and also personal injury.
34 00 010 CHECKING THICKNESS OF BRAKE PAD
IMPORTANT: The corresponding system must be deactivated on vehicles equipped with
ASC+T or DSC.
The ASC+T or DSC telltale and warning light must light up in the instrument
cluster!
IMPORTANT: Only brake test stands (analyzers) with test speeds of 2.5-6 km/h may be used.
2008 BMW 328xi
BRAKES Brakes - Repair Instructions - 325i, 325xi, 330i, 330xi, 328i, 328xi, 335i and 335xi
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Special tools required:
34 1 260
Insert special tool 34 1 260 through rim into opening for brake pad wear indicator.
Press special tool onto brake pad. Slide ring (1) in direction of arrow up to stop and read off measured value.
Safe Limit For Lining Wear, Front Brake.
Safe Limit For Lining Wear, Rear Brake.
Fig. 2: Identifying Special Tool (34 1 260)
Courtesy of BMW OF NORTH AMERICA, INC.
34 00 025 REPLACING FLUID IN ABS/ASC+T BRAKE SYSTEM
NOTE: The thickness of the outer brake pads can be determined without removing the
wheels.
If necessary, move car until opening for brake pad wear indicator (brake pad)
can be seen through rim styling.
NOTE:
A. Brake disk
B. Brake pad with backplate
NOTE: Read And Comply With General Information.
IMPORTANT: When carrying out repairs to the brake system, follow the procedure set out in
Bleeding Brake System With Dsc.
2008 BMW 328xi
BRAKES Brakes - Repair Instructions - 325i, 325xi, 330i, 330xi, 328i, 328xi, 335i and 335xi
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Unclip retaining tabs (1).
Pull cover (3) out of guide (2) and remove.
Fig. 3: Identifying Brake System Retaining Tabs, Cover And Guide
Courtesy of BMW OF NORTH AMERICA, INC.
Connect brake fluid changer to expansion tank and switch on.
Fig. 4: Identifying Brake Fluid Changer
Courtesy of BMW OF NORTH AMERICA, INC.
Flushing brake system completely
Connect bleeder hose with collectin g tra y to bleeder valve on rear ri g ht brake caliper.
NOTE: Check relevant Operating Instructions for each device.
Charging pressure should not exceed 2 bar.
2008 BMW 328xi
BRAKES Brakes - Repair Instructions - 325i, 325xi, 330i, 330xi, 328i, 328xi, 335i and 335xi
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Open bleeder valve and purge until clear, bubble-free brake fluid emerges.
Close bleed valve.
Follow same procedure on rear left, front right and front left wheel brake.
Fig. 5: Identifying Rear Right Brake Caliper Bleeder Valve
Courtesy of BMW OF NORTH AMERICA, INC.
Switch off brake fluid changer and remove from expansion tank.
Check brake fluid level.
Close expansion tank.
NOTE: The clutch slave cylinder must also be scavenged in vehicles with manual
transmissions.
NOTE: Pay attention to rubber seal (1) in sealing cap.
2008 BMW 328xi
BRAKES Brakes - Repair Instructions - 325i, 325xi, 330i, 330xi, 328i, 328xi, 335i and 335xi
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Fi g . 6: Identif y in g Expansion Tank, Brake Fluid Level And Sealin g Cap Rubber Seal
Courtesy of BMW OF NORTH AMERICA, INC.
34 00 050 BLEEDING BRAKE SYSTEM WITH DSC
Connect bleeder unit with max. 2 bar filling pressure.
A second person is needed to help carry out this work.
Unclip retaining tabs (1).
Pull cover (3) out of guide (2) and remove.
Fig. 7: Identifying Brake System Retaining Tabs, Cover And Guide
Courtesy of BMW OF NORTH AMERICA, INC.
Connect DIS.
Select path: Service functions - Chassis/Suspension - Slip control systems - Bleeding procedure.
Connect brake fluid chan g er to expansion tank and switch on.
NOTE: Read And Comply With General Information.
When replacing or repairing, observe the filling and bleeding instructions for
the following parts:
Tandem brake master cylinder
Hydraulic unit
Components and connecting lines which are fitted between these
assemblies.
2008 BMW 328xi
BRAKES Brakes - Repair Instructions - 325i, 325xi, 330i, 330xi, 328i, 328xi, 335i and 335xi
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Fig. 8: Identifying Brake Fluid Changer
Courtesy of BMW OF NORTH AMERICA, INC.
Flushing brake system completely
Connect bleeder hose with collecting tray to bleeder valve on rear right brake caliper.
Open bleeder valve and purge until clear, bubble-free brake fluid emerges.
Close bleed valve.
Follow same procedure on rear left, front right and front left wheel brake.
Fig. 9: Identifying Rear Right Brake Caliper Bleeder Valve
Courtesy of BMW OF NORTH AMERICA, INC.
Bleeding rear-axle brake circuit
IMPORTANT: Check relevant Operating Instructions for each device.
Charging pressure should not exceed 2 bar.
2008 BMW 328xi
BRAKES Brakes - Repair Instructions - 325i, 325xi, 330i, 330xi, 328i, 328xi, 335i and 335xi
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Connect bleeder hose with collecting tray to bleeder valve on rear right brake caliper.
Close bleeder valve.
Run bleeding routine with DIS with bleeder valve open.
After completing routine, press brake pedal 5 times to floor; clear and bubble-free brake fluid must flow out.
Close bleed valve.
Repeat procedure at rear left.
Fig. 10: Identifying Rear Right Brake Caliper Bleeder Valve
Courtesy of BMW OF NORTH AMERICA, INC.
Bleeding front-axle brake circuit
Connect bleeder hose with collecting tray to bleeder valve on front right brake caliper.
Close bleeder valve.
Run bleeding routine with DIS with bleeder valve open.
After completing routine, press brake pedal 5 times to floor, clear and bubble-free brake fluid must flow out.
Close bleed valve.
Repeat procedure at front left.
2008 BMW 328xi
BRAKES Brakes - Repair Instructions - 325i, 325xi, 330i, 330xi, 328i, 328xi, 335i and 335xi
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