Changing brake pads, brake discs and brake calipers

Carry out a visual inspection

Before carrying out the repair, it is advisable to check all relevant components in the area of the axle and wheel brake, such as the tires, brake hose, and transverse control arm, for example, for damage.

• Defective parts must be replaced without fail

Remove the brake caliper, take out the housing retaining spring

CAUTION

The retaining spring is preloaded. If it jumps sideways it can cause injury.

Unclip the wiring harness of the brake pad wear indicator

• To do so, open the connector housing (1) in the wheel well, unlock the connector, and detach the wiring harness from the combination holder (2)

Remove the protective plugs of the guide bolts

Inspect protective plugs and damping sleeves for damage.

• Defective parts must be replaced without fail

Note:

Water and dirt ingress cause corrosion on the guide bolts, which will impair the function of the brake caliper. This in turn leads to one-sided braking behavior and premature wear.

Undo and remove the two fixing screws

Tools required:

• 7 mm Allan key

Remove the brake caliper from the brake anchor plate

Pull the brake caliper back and off. Then take the outer brake pad out of the brake caliper.

Remove the brake pad on the piston side

As the brake pad on the piston side is mounted with a retaining spring in the piston, it must be pulled forward in order to remove it. Take the wear indicator out of the pad.

Note:

As the wear indicator loses its adhesion once it has been removed from the brake pad, this must always be replaced once removed.

Tie up the brake caliper on the suspension strut using a suitable hook

• In doing so, avoid twisting or kinking the brake hose
• Detach the brake hose at the holder on the suspension strut if necessary

Note:

To avoid damage, do not leave the brake caliper hanging from the brake hose!

Slacken and unscrew the fixing screws of the caliper anchor bracket

• Remove the caliper anchor bracket and check it for damage

Check the minimum brake disc thickness

Check the wear limit of the brake disc using a suitable tool.

• Place a gage at several measuring points (A) over the friction ring and take measurements
• Compare the lowest value with the reference value (minimum thickness)

Reference value

The reference value in millimeters is stamped on the outer edge or on the brake disc pot.

• MIN TH = Minimum Thickness
• If the thickness falls below this reference value, replace the brake disc

Remove the brake disc

• Undo the fixing screw
• Remove the brake disc

Note:

If the brake discs are sticking, carefully tap the bottom of the brake disc pot with a rubber hammer.

Check the wheel hub

• Check the surface for corrosion and damage
• Check the thread for damage

Clean the contact face of the wheel hub

• Remove dirt and traces of corrosion using a suitable tool

Note:

Unevenness of the contact face can lead to warping of the brake disc and therefore axial runout!

Protection against corrosion

The contact face of the wheel hub must be undamaged, rust-free, clean, and metallically bright. To protect against corrosion, apply a thin coating of spay oil to the contact face then wipe off with a lint-free cloth.

Note:

Do not grease the surface of the wheel hub after cleaning!

• The grease could come into contact with the brake during rotation.
• The tightening torque of the rims could then no longer be ensured.

Mount the brake disc

Mount the brake disc and fasten with fixing screw.

Note:

Observe the tightening torque!

Prepare the caliper anchor bracket for mounting

The recommended way to do this is to remove the anchor bracket and clamp it in a vise.

• Clean the anchor bracket with brake cleaner
• Carefully remove any corrosion on the guide surfaces using a wire brush or file

Caution

Mechanical damage to the guide surfaces must be avoided at all costs!

Install the caliper anchor bracket

• Insert screws and tighten (Fig.1)
• Observe the tightening torque!

Then apply a thin coating of non-conductive, non-metallic anti-squeal paste to the clean contact faces of the caliper anchor bracket (Fig.2) .

Push the brake piston right back

Push the brake piston right back using the reset tool.

• Check the dust protection sleeve of the piston for damage

Note:

Observe the brake fluid level in the expansion tank when pushing back the pistons. Drain the tank beforehand if necessary.

Clean the brake caliper with brake cleaner

Thinly coat the contact face (A) of the brake piston with anti-squeal paste.

• Clean the contact face (B) and also thinly coat with anti-squeal paste
• Clean the contact face (C) of the hammer heads / brake calipers and thinly coat with anti-squeal paste

Install the brake pads

• Thinly lubricate the brake pads only at the hammer head (E) and in the area of the contact faces (F) on the brake caliper using a non-metallic anti-squeal paste
• Insert the outer brake pad in the caliper anchor bracket
• Insert the pad on the piston side in the brake caliper
• Fit the brake caliper on the caliper anchor bracket

Note:

New brake pads may only be installed if the brake disc is thicker than the minimum brake disc thickness (MIN TH).

Clean and check the guide screws

• Check the thread
• Damaged screws must be replaced without fail

After cleaning, grease the contact surfaces of the guide screws with a thin coating of grease. Use only a silicone-based grease in this area.

Mount the brake caliper

Mount the brake caliper and fasten with the guide screws.

• Reattach the brake hose and wear indicator cable in the combination holder
• Insert the retaining spring

Note:

Observe the tightening torque!

Install and connect a new wear indicator

• Make sure the wear indicator is seated correctly in the brake pad

Clip the cables and brake hose back into the combination holder.

Note:

Make sure that the brake hose is not twisted and is correctly fastened in the holder.

Establish the working position

Press the brake pedal several times up to two thirds of the way down, and not further, to enable the brake pads and pistons to take up their working positions.

Note:

If you press the pedal down fully, this can damage the brake master cylinder!

Check the level of brake fluid in the expansion tank

Check the brake fluid level in the expansion tank and fill up to the "MAX" marking if necessary.

• Change the brake fluid if necessary

Note:

Only use new brake fluid that has been approved for the vehicle type.

Clean the brake disc

Clean the brake disc after mounting the brake caliper.

• The friction ring must be free of dirt and grease
• The disc pot and thread must be clean and free of foreign particles

Mount wheels

• Clean the rim contact face before mounting the wheel
• Observe the tightening torque of the wheel bolts!

Service reset

Once the brake pad and wear indicator have been replaced, the Condition Based Service indicator must be reset using a suitable diagnostic unit as specified by the vehicle manufacturer.

Info:

The CBS maintenance system analyses the actual service requirement of the vehicle. It measures the condition of the most important wearing parts and operating fluids and monitors the individual service scopes.

Function check and test drive

Once the repair has been carried out, it is essential to perform a functional check of the brake system.

• Carry out a test drive to run in the brake system according to the specifications of the vehicle manufacturer
• Check the function of the brake system on the brake test stand

Attention:

In this case, please observe the general information on braking in new brake discs and brake pads!