Handbrake failure
Replace handbrake cable
Here you will find useful basic information and valuable tips all about damage assessment of parking brakes.
The following repair notes are based on the example of a Mazda 6 but they can also be applied to identical vehicle models. In our case example, the handbrake lever cannot be operated. The service brake on the rear axle works trouble-free and showed sufficient braking values on the brake test stand.
Important safety note
The following technical information and practical tips have been compiled by HELLA in order to provide professional support to vehicle workshops in their day-to-day work. The information provided on this website is intended for suitably qualified personnel only.
TABLE OF CONTENTS
Handbrake failure: Causes of failure
The handbrake, also known as the parking brake, has the task of securing a stationary or parked vehicle and of preventing it from rolling away when no driver is present in the vehicle. With the mechanical handbrake, the braking force is transferred to the wheel brakes of the rear axle via cables when the handbrake lever is operated using muscular pulling force.
A defective handbrake cable first becomes apparent when the parking brake fails.
- A frequent cause of handbrake failure is operational impairment as a result of external damage or contamination.
- A defect in the covering or dust protection sleeve can cause water or dirt to penetrate, which can lead to corrosion and jamming of the cables.
- In addition, moisture and frost can cause the cables to freeze up during cold seasons.
Please note
The following repair notes are based on the example of a Mazda 6 but they can also be applied to identical vehicle models. In our case example, the handbrake lever cannot be operated. The service brake on the rear axle works trouble-free and showed sufficient braking values on the brake test stand.
Changing handbrake cable for a Mazda 6: Video
Checking handbrake and changing handbrake cable
Using the example of a Mazda 6, we show in our video how to check the handbrake for faults and how to replace the handbrake cable professionally.
Checking handbrake for faults and replacing handbrake cable: Instructions
Check handbrake for faults
Figure 1: Checking dust protection sleeve on handbrake cable
In order to determine the cause of the defect, all components of the parking brake should now be checked.
- Raise the vehicle and remove the rear wheels if necessary
- Check handbrake cables for damage and secure fastening
Damage to the dust protection sleeves on the cables was found here (Figure 1).
Release the handbrake cable for further diagnosis
- To do this, remove the rear ashtray cover in the centre console and loosen the adjusting nut of the parking brake until the handbrake lever can be moved slightly
Then check the mobility of the handbrake levers on the rear brake callipers
- Use a screwdriver to slightly deflect the lever in the pulling direction
The handbrake levers and operating levers on both brake callipers move freely and show no visible defects.
Remove parking brake cable
Figure 2: Damaged dust protection sleeves on the handbrake cable
To remove the handbrake cable package, carry out the following work
- Remove the cover from the handbrake lever, i.e. on the centre console
- Loosen the adjusting nut for the handbrake lever until the bolts of the cables move freely
- Unhook fastening bolts
- Remove lower vehicle trims and heat shield
- If necessary, remove the exhaust system from the brackets
- Loosen the mounting plate and brackets on the handbrake cable
- Undo the handbrake cable on the brake callipers and remove the cable
After dismantling, the cause could clearly be attributed to the handbrake cable. The cable could no longer be moved in the Bowden cable. Internal impurities and corrosion have led to an impairment of operating movement (Figure 2).
Check and reset mechanical adjustment devices
Figure 3: Turning back the brake piston correctly with a suitable reset tool
Before the new handbrake cable is installed and adjusted, the mechanical adjustment devices in the two brake callipers of the rear axle should first be checked and reset. Correct adjustment of the parking brake is only possible if the parking brake Bowden cables and all moving parts of the parking brake move easily and are functional.
To do this, remove the brake calliper and operate the mechanical lever on the brake calliper until the brake piston extends slightly. After successful testing, turn the piston back completely using a reset tool (Figure 3).
While this task is being carried out, all other components such as brake blocks/pads or guide bolts should be checked for wear and functionality at the same time. Worn or defective components should be replaced.
Put brake callipers back together and reinstall. Then bring the brake pistons into their working position by means of light pedal pumping.
Installing the handbrake cable
Joining cable onto handbrake lever with adjusting nut
Reinstall the new handbrake cable in reverse order.
- Hook the cable to the brake callipers and secure with a fixing plate
- Insert the cable at the top in the handbrake cable holder on the handbrake operating mechanism
- Install and fasten the handbrake cable to the underside in line with the mounting points
- Turn the adjusting nut on the handbrake lever until "no play" tension is achieved or the handbrake levers on the brake calliper lift slightly off the limit stop
Adjusting the handbrake cable - basic setting
- Tighten the handbrake lever to 3-4 detents
- Tighten the adjusting nut until the rear wheels are difficult to turn by hand
- Release handbrake lever
- The rear wheels must now be able to turn freely again. If necessary, turn the adjusting nut back slightly
- Tighten and release the handbrake lever several times using medium manual force
- Operate brake pedal several times with moderate force
The handbrake lever travel should be adjusted in such a way that a blocking of the brake is achieved between 4 - 7 detents.
Check handbrake indicator light
- Set ignition key to ON
- Tighten handbrake lever to detent 1
The indicator lamp should now light up. The wheels must now still turn freely and the rear wheel brakes not drag.
After the basic adjustment, automatic readjustment in the brake callipers of the rear wheel brake means that readjustment of the handbrake is no longer necessary.
Finally check the effectiveness of the handbrake on the brake test stand.
Repair notes
In connection with this information, please also observe the maintenance and repair instructions of each individual vehicle manufacturer!
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