Don’t estimate when it comes to parking brake adjustments

Don’t estimate when it comes to parking brake adjustments

Let’s discuss a couple of different components of parking brakes to find out the best practices for adjusting them.

The parking or emergency brake has two crucial functions. First, it must hold the vehicle on an incline and second, stop it within a specific distance if the hydraulic brakes fail. These standards, established by the Department of Transportation, must be met with minimal force. Let’s discuss a couple of different components of parking brakes to find out the best practices for adjusting them.

You should never guess or estimate when adjusting parking brakes. For example, relying on feel to back off an adjuster for some drum applications can lead to problems and these applications may have clearance specifications because the shoe can swell from moisture or expand at a different rate than the drum, causing brake drag and noise.

If the manual recommends using a brake drum measurement and resetting tool, make sure to use it. If it specifies backing off the adjustment by five teeth, follow that exactly — back it off by five teeth, not four or six.

Some vehicles feature a self-adjusting parking brake that adjusts the cables at the parking brake pedal rather than at the wheels. This self-adjustment manages the length of cable running from the foot pedal under the dash to the equalizer bar, ensuring consistent pedal travel throughout the life of the brake shoes. If any work is done on the parking brake at the wheels, adjustments are necessary.

For certain full-sized trucks, first, adjust the shoe-to-drum clearance. Then, remove the self-adjuster lockout pin, fully apply and release the parking brake pedal three times, and replace the lockout pin.

Keep in mind: These systems have limited adjustment capabilities. Some slack can be removed from the cable under the vehicle with a turnbuckle, but if the cable is adjusted to its maximum limit, it will need to be replaced.

In most vehicles, the left and right parking brake cables connect to a lever linkage called an “equalizer” yoke located under the vehicle. This yoke balances the force applied to both cables when the parking brake is engaged. The equalizer linkage is then connected to a single cable that leads to the parking brake lever or pedal. An adjustment screw may be found on the front cable where it connects to the equalizer or where it attaches to the parking brake lever.

The equalizer linkage can rust, hindering proper brake application and release. Additionally, the hinge pivot can break, making the parking brake ineffective. A common sign of a worn hinge pivot is normal lever or pedal travel, but the parking brake will not hold the car on a hill.

All in all, maintaining and properly adjusting the parking or emergency brake is essential for vehicle safety. These brakes have to reliably hold a vehicle on an incline and serve as a crucial backup if the hydraulic brakes fail. Following the specific adjustment procedures outlined in the vehicle’s manual is vital to avoid issues like brake drag and noise.

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