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What happens if you don't use your parking brake?

Jun 08, 2023Jun 08, 2023

If you don't use it, you'll lose it

One of the most misused, abused, and forgotten systems of any passenger vehicle or light truck has to be its parking brake. Leaving these components to the ravages of our driving and parking environments is only asking for trouble and expense down the road, however. This can have a negative effect on braking performance — a critical safety issue.

Parking brakes are sometimes — and very incorrectly — referred to as emergency brakes. The overwhelming majority of vehicles’ parking brakes only operate on the rear wheels, however, so trying to panic-stop with only the parking brake can lead to very unpredictable and uncontrollable handling.

Most parking-brake systems still operate via a manual lever and cable system that activates the rear brakes when applied. About the only innovation that’s occurred for this feature in decades has been the introduction of electrically operated systems, which use electric servos to apply the rear brakes with the press of a button.

Few drivers with automatic-transmission-equipped vehicles regularly use their parking brakes, so like all moving metal things that don’t move for extended periods of time, they can stop moving when neglected. For those who think parking brakes are unnecessary on an automatic transmission vehicle, consider that your one-plus-ton cage of rolling steel is only held in place by a small rod about the diameter of a pencil when the drive lever is in park. That device, known as a park pawl, is inserted into the teeth of the transmission’s final-drive gear when you select park on your gearshift.

Ever notice that your vehicle will roll a bit when parked on even the slightest incline, after putting it in park and releasing the main brake? That’s the movement permitted by the generous tolerance between the park pawl and the transmission gear. Over the years and miles, and especially if the roll back or forward is repeated often enough on inclines, it will cause the pawl rod to wear slightly. This can make it hard to pull the lever out of park on a steeper incline when you’re ready to take off. Enough wear can necessitate its replacement, which requires transmission removal and teardown — ouch on the wallet!

Some parking brakes on vehicles with rear disc brakes use mechanical or electrical actuators on the rear brake calipers that simply lock the normal brake pads onto the rotors to provide a ‘park brake’ function, while others use brake rotors with a built-in drum that houses small brake shoes and hardware. The problem with the latter is that a technician won’t have any idea if those brake shoes require replacement or maintenance without removing the drum-rotor unit. This can be a small Pandora’s Box on older vehicles, leaving for a surprise bump in any repair estimates. Simple tip: when presented with a repair estimate for repair work on such a system when the rears haven’t been removed for inspection, ask your service provider to quote costs for new park-brake shoe set and hardware replacement. That way, the only surprise at bill time will be the pleasant one if those components don’t have to be replaced.

The best way to keep these safety systems in working order is to use the parking brake regularly. Even when parked on a relatively level surface, activating them will prevent any rolling back or forward, and if you park in a tight spot the vehicle can’t be accidentally nudged into a curb stone or wall.

If you ever get stuck when a different driver solidly applies a cable-operated park brake on your ride and it won’t release, you may be able avoid a towing service by trying to release it by getting down and grabbing the cables leading to the inside of each rear wheel and giving them a few twists and turns. Then, with the parking brake lever or pedal released, gently rock the vehicle back and forth a few times by shifting it from drive to reverse.

If you’re doing some DIY driveway brake service on anything over 3 or 4 years of age that involves a drum/rotor system with hidden park-brake shoes, do yourself a favour and have a shoe set and full hardware kit on hand just in case — it can easily save a lot of time and swearing. And don’t ever think you can return a sticking or seized cable to use by working it back and forth with lubricant; it will almost always seize again. Replacing these is the only option if you want an operational parking brake for the long term.

One of our longest contributors (over 30 years) Brian Turner is a veteran of the automotive repair world with over 4 decades of service. His career has taken him from independent shop management to a stint at AMC Jeep Renault’s Canadian head office to a variety of OEM dealerships in parts and service management. He still has a busy day job at a dealership counter today.

He began his writing for the Ottawa Citizen where he penned the ‘Ask the Expert’ column, answering motoring questions for thousands of readers. He took his pen on the road, so to speak, and offered similar consumer advice through several smaller news publishers over the years.

As of late he’s taken to the airwaves as a news broadcaster for Lake 88 FM radio where he also hosts his own weekly call-in show on, what else, consumer advice. You can also catch him every other Monday on Calgary 770 AM talk radio when he delivers Motoring Mondays to an eager audience during the afternoon drive time.

His mission is to break down the mysteries of modern automotive technology to help steer vehicle owners down the right road to smooth motoring.


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