Driving with parking brake?

January 11, 2007 9:12 PM

Car driven with parking brake on; how badly am I screwed?

I drove my Harvard-educated girlfriend to her office, where I parked the car. Later that night, she used that car to pick me up. As I'm getting in the passenger side, I smell something like burning rubber. "Hey," she says, "the brake light's on." Yeah, she drove a quarter mile with the parking brake on, including out of a parking garage. We disengaged it, and the smell went away eventually, but now I'm trying to figure out how much damage might have been done in the meantime. Google wasn't especially helpful; we found this Car Talk exchange, implying a full inspection of the rear wheels is needed, but this wasn't anywhere near 15 miles.

posted by commander_cool to travel & transportation (22 answers total)

A quarter mile is essentially nothing to worry about. The next time it's in for a tune-up, ask them to check the rear brakes, but it's probably fine.
posted by one_bean at 9:17 PM on January 11, 2007

I did this when I was in college and everything was fine. Good luck.
posted by salvia at 9:21 PM on January 11, 2007

When, um, a friend of mine (yeah, that's it, a friend of mine) did this, the parking brake seized up a little as a result so it was still partially applied afterwards (even though the lever was back in the original position and the dashboard light wasn't on). So damage continued to be done.

I'd have someone look at it (and show you the damage if they say it's damaged).
posted by winston at 9:21 PM on January 11, 2007

totally anecdotal but she probably just wore out the pads more. I've heard stories from coworkers about doing the same thing with no ill effect. I know that, at least in my car, there's a seperate set of drum brakes in the back that are the emergency brake (it's got discs for the regular brakes), and if you drive with the ebrake on it's pretty much like hitting the gas and the brake pedal at the same time. if it was driven a whole lot like that, the pads could be worn down enough to cause damage, but I doubt a quarter mile would do it. if you're worried, best to get it checked by a reputable brake shop.
posted by mrg at 9:22 PM on January 11, 2007

Depends on the car. Some cars use the main brakes as the parking brake as well, others have separate discs or drums. Verify which type you have.

1) If you have a separate system for the parking brakes, then you might have done some damage to that, but it won't affect the service brakes. Try the parking brake and see if it will still hold on the difficult hill of your choice.

2) If you have an integral system, have the discs or drums inspected.

A quarter mile is not far, but the amount of wear and damage depends on how hard the parking brake lever was pulled.
posted by jet_silver at 9:22 PM on January 11, 2007

People have driven for much much longer distances and periods of time with the brake on. I wouldn't worry too much about it.
posted by blue_beetle at 9:22 PM on January 11, 2007

You should be okay...... just check and see that the parking brake is still working.....

To do this, have a friend ride with youand find a nice expanse of parking lot. Turn the car off. Turn the key to the "run" position, but don't start the car. Engage the parking brake. Place the trans into Neutral. You and your friend try and push the car. If it rolls relatively easily, you will need the e-brake adjusted. If it does not, you should be okay.

The make/model/year of the car and how many miles it has would be useful info here, as well. If the car hasn't had the rear brakes serviced within the past 50,000 miles or so, they should be inspected anyways.

I personally wouldn't be too worried about it, as long as you notice nothing different in how the brake pedal feels now versus as to how it felt before this happened.
posted by peewinkle at 9:34 PM on January 11, 2007

You should give her a hard time and have her 'make it up' to you even though it's not a big deal.

I know someone who took a driving test WITH the break on, and the car was fine...he is still being made fun of even 11 years later...that reminds me...I have to make fun of him today.
posted by icollectpurses at 9:50 PM on January 11, 2007

I've done this a few times (2 or 3 maybe? maybe more) and to be honest I never even thought about potential damage to the vehicle. (I find it easy to forget when driving a car with a foot-operated parking brake, but I've forgotten in my own car as well, which has a hand-brake.)

peewinkle's idea is a good one though and I'm definitely tempted to try it, just to double-check I've done no damage; I've done less than 5,000km in my current car so the parking brake should still be relatively good.
posted by snap, crackle and pop at 9:54 PM on January 11, 2007

How much damage she did depends on the type of rear brake system you have (drum, disc, or disc w/aux drum), and how hot the brakes got. They could get quite hot if the parking brake were on fully, and she drove the car in low gear, down a parking incline, and then a further 1/4 mile. Once the brake drum or disc is approaching red hot, related mechanical parts, such as the pad/caliper assembly for disc brakes, or the brake shoes for drum brakes, will also be hot, and they can raise the temperature of fluid filled parts like the caliper or brake slave cylinders to temperatures where the brake fluid boils, leading to leakage of brake fluid from these parts. That's particularly likely if the brakes already have significant mileage on them, and the brake fluid, which is hygroscopic ("water loving") has absorbed significant water vapor from the air, in use.

In the best case, you have conventional drum brakes on a low mileage car, the parking brake was set lightly, and she slowly crept out the parking garage where the car had been parked at street level, and down the street 1/4 mile at 15 mph or less, to pick you up. In this case, she probably did little or no permanent damage to the brake system, although it would be good if you could back the car up several hundred feet and bring it to a stop, several times, to allow the rear brake self-adjuster mechanisms to ratchet any additional play out of the rear brakes. And then, I'd try a few cycles of accelerating to 20 mph in the forward direction, and applying the brakes to stop, to see if there was any new pulling or squealing/squeaking noises that seemed brake related. I'd keep a close eye on the ground around the rear wheels for the next few weeks, and see if any fluid discoloration appears, and I'd keep an eye on the brake master cylinder level very closely for the next few weeks, too. If there are any signs of fluid leakage from either of these indicators, you'll need to pull the rear wheels and brake drums to directly inspect the brake slave cylinders for leakage. Higher wear mileage before this incident increases the likelihood she cooked the shoes and slave cylinders, as the brake drum friction surface is bound to be thinner, as does having the car parked up on the 5th floor of a parking garage, and/or driving it 30-45 mph getting down the street.

If you have disc brakes, there are no auto-adjusters to reset by backing up. And you can directly observe the caliper assemblies for fluid leakage, but otherwise the general ideas for likelihood of damage relating to parking level position, prior vehicle mileage and max speed hold.

If you have combo disc/drum brakes, she could have cooked the small drum parking brakes pretty easily. They're designed to hold the car in static friction, and maybe stop it in an emergency, but they have compartively small thermal masses, and shoes. In most cars with these kind of hybrid rear brakes, they don't have internal hydraulic slave cylinders of full sized drum brakes, nor may they have auto-adjusters that work when the car is put in reverse.

Don't muck around with brakes if you don't know what you're doing. Especially in winter. And even more especially if you are living, as your comment about your girl friend's alma mater might indicate, in New England.
posted by paulsc at 10:22 PM on January 11, 2007

our guitar player drove a few miles with it on in our 15 passenger van the day we were leaving for a 6 week full US tour, and it started smoking and he freaked out, we took it to our mechanic and he just made fun of us and sent us on our way. got back from about 10k miles with no problems (and put a ton more on problem free, before we wrecked it).

i wouldn't worry at all.
posted by teishu at 10:42 PM on January 11, 2007

My father uses the parking brake when he parks, my mother doesn't, so she's almost always driving around the '96 Galant with it on. Eventually the parking brake completely stopped working (i.e. engaging it has almost no effect), but the rest of the car was fine, including the main brake. Mind you, this was after a few years of her doing this all the time.

In high school I drove around a second family car (an '85 Volvo) that sometimes had a problem with the main brakes going out. My mother was not allowed to drive this second car, because my father and I needed to be sure that when the main brakes failed the parking brake would actually work.
posted by Famous at 10:46 PM on January 11, 2007

It's a Prius with 17000 miles on it: front disc, rear drum, regenerative brakes.
posted by commander_cool at 10:50 PM on January 11, 2007

But the parking garage was below-ground, so she went about two or three stories uphill.
posted by commander_cool at 10:53 PM on January 11, 2007

Check out the Prius Wikipedia page and visit some of the 'Enthusiast sites' listed. Ask one of those sites and you'll probably find true Prius Motorheads who know every little detail about the car and can give you really good advice. I just got a Scion and spent last nite reading some Scion forums and learned loads about my car. The people on these enthusiast sites will have taken their Prius apart and put it back together and hacked the car during the process, and they probably know more about it than the dealer.
posted by zengargoyle at 11:29 PM on January 11, 2007

It really doesn't matter whether she went uphill or downhill. The braking force is a constant value determined only by how hard the parking brake was applied (neglecting possible brake fade). The distance she went determines the total heat energy generated and the speed she went determines the rate of heating and how hot the brakes get.

So the only three factors of importance are how hard the brake was applied, how far she drove, and how fast she drove. I'm guessing that the brake wasn't applied very hard or she would have really noticed a problem trying to drive up hill.

If you hear some squeaking when brakes are applied, they may have been glazed by the heat. A repair shop can quickly fix this by removing the brake shoes and roughing up the surface with some emery cloth.
posted by JackFlash at 2:05 AM on January 12, 2007

There is nothing to worry about.

To quote Mitch Hedberg:

I rent a lot of cars, but I don't always know everything about them. So a lot of times, I drive for like ten miles with the emergency brake on. That doesn't say a lot for me, but it really doesn't say a lot for the emergency brake. It's really not an emergency brake, it's an emergency "make the car smell funny" lever.

posted by Tacos Are Pretty Great at 7:14 AM on January 12, 2007

Also check out this AskMe for more answers.
posted by TedW at 7:16 AM on January 12, 2007

Just wanted to add that once in high school my youth group drove in a few 15-passenger vans out to Colorado (from Detroit). One of the group leaders was leading the pack and all of us behind her van were sniffing the air saying "Wow, this is some fresh mountain air, huh?" When she finally stopped because the tires started smoking, we realized she had been driving uphill with her parking brake on for a good 15 miles.
We made it there and back with no problems, but, if I recall correctly, we did take it in to a shop to make sure. If we did, there wasn't much damage because we were never without all of our vehicles.
Good luck!
posted by slyboots421 at 8:34 AM on January 12, 2007

If it's not stick-shift, you really have no reason to use a parking brake anyway. Just a thought.
posted by owl at 9:00 AM on January 12, 2007

If it's not stick-shift, you really have no reason to use a parking brake anyway.

Very not true for a variety of reasons. Keep using your brake.
posted by phearlez at 9:27 AM on January 12, 2007

Pretty much the only essential time to use a parking break is if you're on a very steep hill. You could use it occasionally to keep it in working order (i.e. from atrophying) but in most situations like level parking or even parking on an average incline, the parking break is not necessary.
posted by owl at 9:33 AM on January 15, 2007