When they cut someone's brake line in the movies.

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2,691
Location
WY
I think 1967 was the last year for single reservoir's on brake systems for American passenger cars. Federal mandate iirc. Same for seatbelt requirement I believe.
 
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36,520
Location
ME
I think 1967 was the last year for single reservoir's on brake systems for American passenger cars. Federal mandate iirc. Same for seatbelt requirement I believe.
^ yup, my 1966 biscayne came with a single pot MC. I refitted one from a 1967 with a minor amount of re-plumbing. Car has lap seat belts but no headrests, but those could have been optional?

They also changed the headlight switch shortly thereafter. On mine when I turn on the headlights the parking lights go out. Soon thereafter they remained on, so you could still see how a car fit in the oncoming lane if a headlamp burned out.
 
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10,956
Location
MA
Basically when you lose half your brakes it seems like you don't have any. I've had that happen before in the past, leaking brake lines so that when I hit the brakes, the wheels were locking up and the car wasn't really slowing down that much. So while technically you have half your brakes, braking power probably seems even worse.
 
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79
Location
WI
Even with the split in the reservoir, if the seal inside the master cylinder that separates the two circuits has failed, you will lose the brakes completely. Years ago this happened to me with a 1996 accord; the brake pedal went to the floor after blowing a rear line, and I drove the car to the shop using the handbrake. Putting the pedal in the carpet had no effect.
 
You forgot to mention it happens going down some steep mountain side.
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1,165
Location
Arizona
It doesent make sense to me why OEM brakes wouldn't be 2 separate redundant systems. My experience though was that the old car did have rear when the front went and the newer car lost all brakes from a line leak no matter the reason.
 
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1,353
You’ll lose your brakes.

Master cylinders have two pistons and the brakes are a “split” system, it just doesn’t work as planned. The master has two pistons and each has a rubber cup on the end, when you lose hydraulic pressure in one half of the system, the cup effected, affects the other cup. Because there is no resistance in whatever section is effected, the other piston freely travels causing the pedal to hit the floor. the pistons will physically touch in the bore of the master, but the pressure and braking force just isn’t there to establish a solid enough pedal. The pedal goes to the floor and braking is GREATLY reduced (to the point where your foot will be buried in the floor and the car’s stopping force is diminished to almost nothing). if there’s someone in front of you, you’ll probably not be able to stop. If you are on the highway and taking an exit ramp? You won’t be able to slow down enough to make that ramp.

They really should come up with a proper solution to prevent hydraulic loss....surprised they haven’t already. I guess it really doesn’t happen often enough for federal highway safety organizations to require manufacturers to do anything about it. But they certainly could put safeguards in place to prevent brake failure/hydraulic failure from happening. I guess their simple solution is the e-brake, but they could do a lot better than that.
 
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5,016
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Southeast
Ive personally experienced the loss of a circuit due to a pinhole leak in the reservoir. One circuit went dry while just enough fluid was over the other to make it work. It does create the thought that “I’ve lost my brakes” unless you realize it’s not on the carpet and there are some left. However, one good front wheel in the rain is not much to go on, and for me in a skinny-tire ‘86 escort on a downhill was madenning. Thankfully when it happened to me (I was pretty young) the road was clear and I had a few seconds to figure out the panic stop as the intersection approached. I slung the wheel hard left and that centered the wheel with good brakes in the front, and then at the end the rest of the vehicle slid 90 degrees to a stop. I didn’t like that car. but yeah following the pedal down to the floor is key.

when abs came out, all the standard about dual diagonal circuit brakes seemed to go out the window. I’m pretty sure my 06 tundra had a single brake circuit which split on the axle to both sides. It was a 3 channel ABS. But it had dual MC outputs. there were a lot of 3 circuit abs designs and even a few rear-axle only setups.
 
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1,617
Location
US
Not a line leak, but I've seen a weepy cylinder drain the rear brakes when the car sat for ~8 months at a shop. I felt the pedal go to the floor and went back and said there was a big issue with the brakes. They insisted they were fine, so I drove about 100 feet before I realized that indeed the car WOULD stop, but nothing like it should so got it back to the shop and said no more. They filled and bled the rear circuit, which at least got me home so I could fix it properly.

In that case, the front circuit was 100% okay, full of fluid and bled. The rear circuit was dry. Even though the brakes only do ~20% at most of the braking in that car, it still basically killed its stopping ability.
 
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1,395
Location
Kennett Square, PA
the trick is the "Cut" needs to be a pinhole. Then the brakes wont fail till you're on a cliff near the ocean. :) My 68 impala lost front brakes due to leak the rears still worked ...barely. Today methinks they will all fail if a leak occurs.

Another one that kills me is the Hollywood Hotwire. guy reaches under the dash, yanks out some wires then "Sparks" two of them to start the car and takeoff.
LOL! I always get a big kick out of the Hollywood Hotwire, especially when they make it look realistic by having the perpetrator touch several wire combos before hitting the right one, usually just in the nick of time.
 
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4,449
Location
Guilford, CT
Some thoughts on the parking brake:
1. What's to stop a vandal from cutting the parking brake cable as well? That's what I would do if I cut someone's brakes (not that I would ever do that).

2. It wouldn't even occur to most people to try to use the parking brake to try and stop the car. Remember when Toyota was having those problems with gas pedals sticking and cars were barreling down the highway at 110+ MPH and the drivers couldn't get them to stop? And every keyboard warrior on the internet was saying, "Why wouldn't they just shift into neutral?" or "Why not just turn the engine off?" Most people just don't think of alternative solutions like that, and especially not in the heat of the moment when they're panicking their butts off. It's easy to think of things like that when you're calm and level-headed, sitting at your computer. But when you're actually IN that situation and not level-headed at all, and you haven't recently read some article discussing that issue and the possible solutions (because nobody is going to write the article until AFTER YOU crash), it's not so easy.

3. Some parking brakes work very well, others not so much. Back in high school I had a buddy who had a 2nd gen (98-01) Nissan Altima with rear drum brakes. The parking brake on that car was fantastic; he did many goofy stunts with the rear tires locked up, including locking them up at speed. I find that cars with rear drum brakes have the best parking brakes. How well the brake is adjusted also plays a factor. I just adjusted the brake on my Accord (rear disc) a few weeks ago, since I already had the center console removed anyway and the brake wasn't holding well. Now it will hold the car still by itself on my steep driveway. It won't lock the wheels up at speed, but it'll get the car to a stop eventually.
 
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