Imagine this一you hopped in your car after a long day at the office only to realize that your parking brake’s stuck. The good news is that your vehicle’s not going anywhere. The bad news? So are you.
What Could Cause the Parking Brake to Get Stuck?
Here’s a list of reasons why a parking or emergency brake could get jammed:
Rust or Corrosion
One of the more common reasons parking brakes stick on older vehicles would be due to rusted cables that won’t operate smoothly. This can happen particularly if the parking brakes haven’t been used much for a very long time in salt-road country or icy areas. If a driver applies the park brake, the rusty cable can get fouled in its sheath.
One of the more common reasons parking brakes stick on older vehicles would be due to rusted cables that won’t operate smoothly.
– Richard McCuistian, ASE Certified Master Automobile Technician
The parking brake is also made up of several linkages that transmit force from the pedal, lever, or handle to the brake assembly.
Over time, these linkages could get rusted or corroded, causing the parking brake cable to get stuck. As mentioned, vehicles in icy areas of the country where salt is used on the roads can have park brake issues that are rust-related. Also, pickups or cars that routinely drive through deep, muddy water can develop park brake sticking issues due not only to rust, but also mud and sand fouling the parts. Mechanically applied park brakes are engaged with a lever between the seats or a pedal, and those devices always have a ratchet mechanism of some sort that can malfunction and stick.
Excessive Force
The parking brake could also get jammed if you pulled it too hard. The brake shoes could get stuck against the drum walls and overstretch the brake’s cable.
According to the Federal Motor Vehicle Safety Standard (FMVSS) 135, the hand force required cannot exceed 80 lbs. or a foot force greater than 100 lbs.
Cold Weather
Leaving the parking brake engaged overnight, especially during winter, can cause it to stick or freeze in place.
Stuck electric park brakes can have either mechanical or electrical issues and typically require professional attention.
How to Release a Stuck Parking Brake
Several methods can dislodge a stuck parking brake, but keep in mind that the solution will depend on what’s causing the issue.
For example, if the parking brake’s stuck because of rust or corrosion, disturbing the brakes manually or shifting to drive and reverse might be your best bet at resolving the issue.
If the parking brake is stuck due to cold weather, you might want to try warming up or revving the engine before trying to disengage the brake.
But if all else fails, it might be time to call a trusted mechanic and have your vehicle towed to the nearest repair shop.
Why Is There a Need for an Emergency Brake?
The parking brake was originally introduced as a fail-safe measure in case total brake operation is lost. This is a problem commonly seen in vehicles with a single master cylinder that operates all four brakes.
After 1967, federal regulations required vehicles to have dual or tandem master cylinders so that half of the braking system runs on a separate hydraulic system.
According to the FMVSS 135, the parking brake should be able to hold a fully loaded vehicle stationary on a slope of 20% up or down grade.
Types of Parking Brakes
Parking brakes are most commonly cable operated except on newer vehicles with electronic parking brakes.
How a parking brake is engaged depends on the vehicle. In most cases, the emergency brake can be activated by pulling a lever between the front seats or under the instrument panel, stepping on a pedal, or pushing a button.
Lever Type Parking Brakes
Old vehicles usually come with a stick lever under the instrument panel that activates the brakes. Newer vehicles with bucket seats usually have a center lever between the front seats.
Pulling the lever engages the brakes, and pushing a small button on the lever disengages them.
Push Button
Some new vehicles have a push button that activates the emergency brakes. This button is usually with the other controls on the console.
Pedal-Type Parking Brake
Vehicles with a pedal-type parking brake come with a small pedal located on the left side of the gas pedal. Stepping on the pedal elicits a click and engages the brakes. Pulling on the lever above the pedal releases the brakes.
Parking Brake Mechanisms
There are two types of parking brake mechanisms一drum and caliper-actuated disc parking brakes.
Drum Parking Brakes
Drum parking brakes can produce a high static coefficient of friction, making them ideal parking brakes for cars and light trucks.
Drum parking brakes are classified into two types一integral and rear disc auxiliary drum parking brakes.
In an integral drum parking brake, the rear drum service brakes are activated mechanically. Once the parking brake is engaged, the brake shoe is forced against the brake drum via a lever and strut.
In a rear disc auxiliary drum parking brake, a parking brake drum is formed into the hub of the brake rotor. This brake type is common in vehicles with rear disc service brakes with fixed calipers.
Rear disc auxiliary drum parking brakes use the dual-servo friction assembly for maximum holding power.
Caliper-Actuated Disc Parking Brakes
This type is common in vehicles with rear disc brakes that have floating or sliding brake calipers.
Caliper-actuated disc parking brakes are constructed with a single piston, making them easier to actuate than fixed calipers with multiple pistons.
This type of parking brake is operated by a cable attached to a lever sticking out of the inboard side of the brake caliper.
When to Adjust the Parking Brake Cable
Most vehicle manufacturers note that the parking brake should have a minimum of three or four clicks and a maximum of eight to 10 clicks when applied.
Any number outside that range could mean your vehicle needs parking brake cable adjustment.
Experts also recommend inspecting and adjusting the rear brakes before adjusting the parking brake cable. A parking brake that creates more than 10 clicks usually means the rear brakes are worn out.
In some cases, you might notice that the parking brake can’t hold when the vehicle is on an incline.
What to Consider When Adjusting the Parking Brake Cable
When adjusting the parking brake cable, you must inspect a couple of things in the braking system.
First, both brake shoes should make contact with the anchor pin. The parking brake cable should also feel loose when the brakes are in the “off” position.
Lastly, the parking brake cable should be lubricated properly to prevent freezing. A frozen parking brake can also cause the linings to remain out against the brake drums.
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