The parking brake is usually engaged when you need the car to be stationary in heavy traffic or in a parking spot. You are supposed to engage the parking brake when your car is already at a halt, in order to keep it from moving out from its intended space.
However, there could times that you have forgotten to disengage the parking brake and just drove away. This will leave you wondering: Would driving with the parking brake still engaged cause some damage?
The answer is: it depends.
When the parking brake is engaged, the brake pad and the rotors are actually rubbing hard against each other, thereby preventing the car to move from its place. However, driving while the parking brake is engaged wouldn’t necessarily cause damage. If you are driving at low speeds or have driven for a short distance, then the possibility of the parking brake sustaining damage could be next to zero.
However, if you are driving fast – especially for an extended period of time -- while the parking brake is engaged, the friction between the brake pad and the rotors intensifies and create a lot of heat. This could possibly cause some problems with the system. If this scenario happens, you might not be able to notice this immediately until you smell that something is burning. The burning smell is actually the brake pad getting to hot due to intense friction. Overheated pads would become glazed, making them smooth and slick instead of rough, thereby lessening the effective power of the parking brake.
Moreover, overheated pads can soften or melt the adhesive on the brake linings. This causes brake linings to crack or detach from the brake pads.
In addition, the heat produced by the intense friction between the brake pads and the rotors is absorbed by the brake fluid. Too much heat could make the brake fluid to boil. The brake fluid acts as an incompressible medium that transfers foot pressure on the brake pedal to the brake calipers, enabling the friction material to clamp against the brake discs. In its boiling state, the brake fluid can’t transmit pressure to the brake calipers, resulting to reduced level or even loss of braking force,
The extent of damage when driving while the parking brake is still engaged is also dependent on whether your car is front-wheel drive or a rear-wheel drive unit. If your car is a front-wheel drive unit, its wheels might not turn and the tires might drag. This means you can immediately notice if the parking brake is still engaged.
On rear-wheel drive cars, you might be able to notice right away that the parking brake is still engaged. This is because the engine can easily overpower the brakes. If this happens, more problems can arise as you drive more, such as damage of the wheel bearing, failure of parts related to the braking system or a premature wear of brake components.