Rick's Free Auto Repair Advice

Drove with parking brake on

What to do if you drove with parking brake on

Did I do any damage when I drove with my parking brake on?

Well, that depends on how long you drove and 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.

The parking brake is integral with the disc brake caliper

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. 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 slight 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, it should also 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” inside the rotor hat. 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.

The vehicle has rear drum brakes

This setup is where you can cause the most damage to your brakes by driving with the parking brake on. If you drove with your parking brake on for a long distance, 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.

Check for discoloration on the brake drum or rotor

If the brakes overheated to the point where you discolored the rotor or brake drum, those components must be replaced.

drove with parking brake on

Overheated brake rotor with discoloration and heat cracks

Check the condition of the friction material

Excessive heat can cause brake pads to crack

drove with parking brake on

Overheated, discolored and cracked brake pad

and separate from the backing plate. Those pieces eventually fall off, reducing your braking effectiveness. High heat can also cause the friction material to glaze, which is scorched material that no longer brakes properly. Replace friction material that has cracks or glaze.

Check the brake caliper and wheel cylinders

High heat can damage caliper and wheel cylinder rubber components. Check the calipers and wheel cylinder for proper application and release. If they apply and release without binding, they’re probably ok.

Flush brake fluid

Brake fluid is made with a base component of lubricating polyglycols and solvent polyglycol ethers. Those two components make up 95 to 98% of the brake fluid. The rest, the additive package, contains corrosion inhibitors, anti-oxidants, and anti-foaming agents. The additives are the components MOST affected by overheating. That’s precisely why you should flush the brake fluid after an overheating event.

©, 2018 Rick Muscoplat

Posted on by Rick Muscoplat

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