Did you just get back home and realize you had your parking brake engaged, cruising down the road? Or are you just wondering what happens if someone drives with the parking brake on?
Maybe it is stuck, and it’s too late now that you got it to the shop. Either way, whether curiosity or necessity, we will “break” it all down for you.
While it can be a pretty terrible issue, if you know what is happening, then you are much more likely to spot the offender, and you will be able to make a more educated decision about what to do.
How a Parking Brake Works
To understand what happens when you drive with the emergency brake, it is essential to understand how the parking brake functions.
If your car has an emergency brake with a lever, this lever is connected to a cable. When you pull on the lever, you pull the cable, which in turn activates the parking brake on the rear wheels of your vehicle.
The brake pads push against the rear drums, and this stops your vehicle or keeps it from moving. If your vehicle has an electronic parking brake, the function will be similar, and there is no cable, because it is an electronic parking brake.
Often, manufacturers will use an electronic parking brake when the rear axle has disc brakes and they don’t want to produce a smaller drum brake for the e-brake.
When you activate the electronic parking brake, an electrical motor turns a threaded piston in the caliper, which holds the disc brakes engaged.
Why Do Vehicles Let You Drive with the Emergency Brake Engaged?
If you are not supposed to drive around with your emergency brake engaged, why do vehicles let you drive under these conditions?
The truth is that you should never drive around with your emergency brakes engaged, but it does give you a last resort option to stop your vehicle in the event your traditional brakes fail.
While this is far from ideal, it’s better than rolling down the road with absolutely no brakes! Another, albeit less important, use of the emergency brake while driving is to facilitate drifting!
Sure, you don’t necessarily need this while driving on the street, but when the conditions are right (check with your local car clubs or race tracks), drifting can be a lot of fun and having a manual parking brake makes this a lot easier!
What Happens if You Drive With the Parking Brake On?
Driving with either an electric or manual parking brake engaged will create the same issues.
#1. Burning Smell.
If you are driving with the parking brake on, it will not have the same acceleration that you normally will, and if you drive it too far, you’ll start to smell burning.
The burning smell comes from the overheating of the pads from the excessive friction between the pads and rotors or drums.
While this is a common problem, it’s not really telling you what happens to the system.
#2. Possible Fire.
This is definitely in the worst-case scenario category, but it is something we’ve witnessed. Friction creates a lot of heat, and eventually, the brakes will catch fire if they are hot enough to ignite.
You do not want a fire to erupt on your vehicle, but it will happen if you are driving with the parking brake on.
#3. Glaze Brakes.
This is the most common symptom of driving with your parking brake engaged, but it is also a more severe problem. That constant pressure and friction overheats the brakes, and as they cool down, you could also get a “glaze” over both the pads and the drums/rotors.
Once this occurs, the slick surface significantly reduces your braking power for the vehicle.
Sometimes, just by normal driving, you could work through the glaze, and upon retesting the vehicle’s braking ability, you could restore your brakes’ original working ability; other times, you will have to replace the pads and rotors/drums.
#4. E-Brake Cable Misadjusts.
Your parking brake operates off of a very fine line of adjustment where the brake setting is mounted on the brake lever.
If it is too tight, the brakes will not release fully when you let off the parking brake; if it’s too loose, the parking brake will not engage enough when you apply the parking brake.
When you are driving around with the parking brake engaged, it will eventually wear down the pads. Worn pads will affect the adjustment allowance and potentially make it loose.
If that happens, you will need to re-adjust the parking brake, or it won’t have the stopping power necessary.
What Happens if You Pull the Emergency Brake While Driving?
It’s a question we have all wondered about: What happens if you pull your parking brake while driving down the road? The outcome would not be good under most circumstances.
If you are going at a lower speed, say 5-10 mph, pulling your parking brake with full pressure would cause you to slam on your brakes.
If you are going at higher speeds, it will lock your back brakes and cause you to skid down the road. You could also potentially “fishtail” when the back end of the vehicle slides out to one side.
Of course, this is if you fully engage your emergency brake while driving. You also have the option of gently engaging your emergency brake while driving.
This is known as “feathering the brakes” and will allow you to control the stop. To reiterate, however, this is much less effective than traditional brakes.