Diagnose and Fix Parking Brake Problem

Brakes, Tires and Wheels

By Rodney (Mechanics)

When you fix your brakes, always make sure the parking brake works too.

You might not use the parking brake much, but it’s important to have it in case you need it to stop your car from moving.

The parking brake keeps your car from rolling when you park it. But you can also do that by putting your car in PARK or leaving it in gear. So some people think the parking brake is not needed. But you should still use it sometimes.

Diagnose and Fix Parking Brake

If you don’t use the parking brake often, it can get stuck or make your brake pedal go down more.

Using the parking brake helps keep the cables moving so they don’t rust and get stuck. Using the parking brake also helps the rear brakes stay in the right position for better braking. On cars with four brakes on the wheels, using the parking brake helps the brakes adjust to the wear and tear.

The parking brake is not only for parking. It is also for emergencies. If the normal brakes fail, the driver can pull the parking brake to slow down the car. The rear brakes are not very strong, but they are better than nothing.

Diagnose and Fix Parking Brake Problem

The parking brake system is not complicated. On cars with drum brakes on the back, using the parking brake pulls some cables that move some arms on the brake shoes. This makes the brake shoes press against the drums to stop the wheels. On cars with disc brakes on all wheels, the brake pads press against the rotor by the caliper pistons. This needs either a cam or screw inside the caliper piston that moves the piston out and keeps it there, or a small drum brake inside the rear rotor.

When you have disc brakes on the back with locking calipers, you need to make sure the parking brake cable is not too tight or too loose. If it is too tight, the brakes may not work well or may rub. If it is too loose, the parking brake may not stop the car. Usually, you should hear only four or five “clicks” when you pull the parking brake.

Diagnose and Fix Parking Brake Drum

When you have disc brakes on the back with mini-drums in the rotors, the parking brake works like a normal drum parking brake. Pulling the cable makes the shoes press against the drum to stop the wheel. But unlike a big drum brake, there is no way to adjust the star wheel for the shoe wear. The parking brake is only used when the car is not moving, so the shoes should last a long time unless the parking brake is stuck and makes the shoes rub. It doesn’t matter how thick the shoe linings are as long as they can hold the car on a slope with normal cable pull.

On most cars, the left and right parking brake cables join and are attached to a lever thing called an “equalizer” yoke under the car. The equalizer yoke makes sure both cables get the same amount of force when the parking brake is pulled. The equalizer thing, then, is connected to a single cable that goes to the parking brake lever or pedal. There may be a screw to adjust the cable on the front cable where it connects to the equalizer, or where the cable connects to the parking brake lever.

Rust is the main problem with the brake cables and linkage. Rust can make the cables stick in their covers, stopping the brakes from working or letting go. If one cable gets stuck, the equalizer can’t balance the force and only one wheel will stop. This may not matter when the parking brake is used for parking, but it could be very dangerous if the system is needed for emergency braking. The imbalance would likely make one wheel slide and spin, making the car lose control.

Diagnose and Fix Parking Brake4

The equalizer linkage can also get rusty, messing up the working and letting go of the brakes. Also check the hinge pivot because it can come off, making the parking brake useless.

When you fix your brakes, therefore, always check both parking brake cables and the equalizer linkage. Use the parking brake to see if the linkage is working right and that the brakes will stop the car. Then check to see that the brakes let go completely. If there is any sticking and/or rust, clean and grease the cables (if you can) with brake grease, or change the cables. Also grease the pivot point on the equalizer linkage. Electric Parking Brakes

More and more new cars from different countries have electronic parking brakes that are turned on by a button or lock the rear wheels by themselves when the car is put in park. On some cars, the rear calipers have a small electric motor that presses the brake pads against the brake rotor. These include Audi, BMW, Mercedes, VW and others. On others, there is a cable thing with a motor inside that pulls a cable that goes to each rear brake. If the power goes out to the thing, or the electronic parking brake part is broken, the parking brake may not work or let go. See Electronic Parking Brake (EPB) for more details.

If you are fixing the brakes on one of these cars, you need a special tool from the factory or a similar tool to loosen and let go of the electric calipers before you can safely work on the rear brakes.