Blue Print offers some best practice advice on two brake pad ranges, one for PSA group vehicles, the other for Mazdas.
Part numbers
ADP154305, ADP154351
Models
Various Peugeot, Citroën and DS models
Many Peugeot, Citroën and DS models are equipped with rear brake discs that have an integrated wheel bearing. As a result, this type of assembly allows for significant weight saving, since the brake disc also becomes the wheel hub. This preassembled part also makes replacement quicker and easier for the workshop, whilst eliminating the risk of mounting a bearing with incorrect clearance or seal positioning.
However, care must be taken when fitting this type of brake disc to the stub axle as this disc/bearing assembly is also fitted with a multipole reluctor for the wheel speed sensor.
With the old brake disc removed from the vehicle, the wheel speed sensor should be inspected for excess corrosion surrounding the mounting area. It is important to note that any excess metal corrosion can alter the position of the sensor – affecting its functionality. This can lead to direct contact with the reluctor, causing damage to the new brake disc assembly (Fig.1).
Subsequently, an increased air gap between the sensor and the reluctor can also occur, resulting in an anti-lock brake system fault – logged as a sensor implausibility signal fault code in the brake control unit.
Therefore, during the installation of a new brake disc it should be identified if the speed sensor is in contact with the multipole reluctor, or if the air gap is not correctly aligned. If discovered to be incorrect, the brake disc and speed sensor should be removed. The sensor seating location should be cleaned of corrosion and – if damaged – the sensor refitted or replaced. With the new brake disc re-installed, and the sensor correctly aligned, a clear 1-2mm air gap between the reluctor and the sensor will be visible (Fig.2).
Adjustment unit for handbrake adjustment
Part number
febi 104935
Models
Various BMW models
Function
The handbrake lever pulls on the two cables which transmits the applied force to an expander (adjustment unit for handbrake adjustment) within the brake drum housing for each rear wheel. The expander is attached to the end of the handbrake cable. As the cable is pulled, it causes the expander to open. The expander is forced against the brake shoes where it then pushes the top of the shoes apart. In doing so, it presses the friction material against the inner surface of the brake drum. If the parking brake is functioning correctly, the shoes will press sufficiently to securely lock the wheel.
Cause of failure
Seized operation of the expander or wear is quite common. This causes the parking brake shoes to bind or leads them to not be effective. The parking brake on these vehicles is a drum brake system integrated into the rear brake disc. As a result, the parking brake linings barely wear, and the condition of the hand brake can only be determined when the brake discs are removed. It is recommended that the hand brake shoe expander is replaced when the parking brake shoes are replaced, or, alternatively, every four years.
Rear brake pads, rear brake discs
Part numbers
ADC44288, ADM542112, ADM542114, ADM543124, ADM543127
Models
Mazda 6, Mazda CX-5 equipped with electronic parking brake (EPB)
Problem:
When replacing the rear brake pads and/or the rear brake discs, the vehicle is required to be set into maintenance mode. By doing this, the EPB motor gear unit will operate and allow the brake pistons to be pressed in for brake maintenance purposes.
Cause:
When the EPB is applied, the EPB system detects the current brake disc position and automatically adjusts it to the optimum EPB release position (brake pad to disc clearance). Failure to carry out the correct procedure (i.e. initially setting the vehicle into maintenance mode) will potentially cause an operational problem with the EPB system.
Solution:
When performing repairs and maintenance to the rear brakes on the vehicles listed above, it is important to set the vehicle into maintenance mode as explained on the following page.
Caution: If performing this procedure while the vehicle is on the ground, block the front and rear wheels using wheel blocks. Failure to do this may result in the vehicle moving when the electric parking brake is released.
The EPB system will not work if the battery voltage is insufficient. Therefore, it is advised to use a battery support unit while carrying out this operation.
Setting to maintenance mode
1. Switch the ignition ON (engine off).
2. Release the electric parking brake.
3. Switch the ignition off, and then switch the ignition ON (engine off) within 5 seconds while maintaining the following conditions.
- Press the electric parking brake switch.
- Depress the accelerator pedal fully.
4. Verify that the electric parking brake warning light is illuminated in an amber colour and the mode is switched to maintenance mode.
5. Switch the ignition off. Carry out all necessary repairs or replacement of the rear brakes.
Ending maintenance mode
1. Switch the ignition ON (engine off).
2. Switch the ignition off, and then switch the ignition ON (engine off) within 5 seconds while maintaining the following conditions.
- Pull-up the electric parking brake switch.
- Depress the accelerator pedal fully.
3. Verify that the electric parking brake warning light turns off and the maintenance mode is ended.
4. Switch the ignition off. After all repairs have been completed, check the EPB operation when the engine is running or with a fully charged battery (engine off).
