What to do if you drove with the parking brake on

Understanding the Effects of Driving with the Parking Brake On

Driving with the parking brake on overheats the brake components. In extreme cases, the heat can damage the rubber seals, causing a brake leak that destroys the brake pads or shoes. How much heat you generated depends on how long you drove in that condition and your speed. It also depends on how your brakes felt when you finally realized your mistake. The parking brake mechanism varies depending on whether it applies the rear disc caliper brake pads, a separate set of parking brake pads inside a “drum-in-hat” style rotor, or whether your vehicle is equipped with rear drum brakes.

Damage to a rear disc brake caliper with an integral parking brake mechanism

In this setup, when you engage the parking brake, the cable forces the rear disc brake pads against the rotor, just like it does in a normal stop. However, if you drove with the parking brake on in this setup, you most likely overheated the rear disc brake pads.

Overheated brake pads form a shiny glaze that reduces stopping power

If you drove for a long time, chances are you glazed over the surface of the rear brake pads. After the brakes cooled down, the damage would show up as a loss in braking power and brake noise. If you notice that, take it to a shop and have the rear brake pads replaced. The rear caliper itself should withstand the higher heat. However, if there are any discoloration (blue or purple) spots on the rotor, those should also be replaced

The blue spots on this rotor indicate that it overheated and must be replaced

The vehicle has rear disc brakes, but the parking brake uses separate brake shoes

In this setup, the cable operates two traditional-style brake shoes that rub against the “drum-in-hat” style rotor. Driving with the parking brake on can overheat the parking brake shoes and cause heat spots to develop in the “drum.”

However, you would not notice any effects once things cool down since the parking brake is only in operation when you apply it. To test the condition of your parking brake after driving with the parking brake on, simply try applying the parking brake at a slow speed to see how it works. If the parking brakes slow your vehicle and prevents it from moving, it’s working. If you have no other brake issues or noise, you probably don’t have to replace anything.

This image shows a traditional rear brake caliper with a separate parking brake and a drum-in-hat rotor

The vehicle has traditional rear drum brakes

This setup is where you can cause the most damage to your brakes if you drove with the parking brake on. Chances are you overheated the brake shoes, the brake fluid, and even the brake drums. In extreme cases, the high heat can damage the rubber seals in the wheel cylinders, causing them to leak brake fluid. If your brake fluid is leaking or low, have your brakes checked out immediately.

The overheating can cause high heat discoloration of the brake drums and that can reduce braking effectiveness and cause brake noise. In a worst-case scenario, driving with your parking brake on with drum brakes can result in having to do a complete brake job on both rear wheels.

In many cases, driving with the parking brake on means you have to replace the brake shoes, springs, drum, and wheel cylinder.

©, 2018 Rick Muscoplat