Stopping if the brakes go out

[theblet]

I'm old school. Never had a vehicle with an electronic park brake. In all of my old vehicles, if the brakes went to the floor, you press the emergency brake to help stop, instead of getting in a wreck.

How does this work on my truck? Can you just press the button, or open the door to trigger it?

 

[Aseras]

You can hit the button for the EPB. it will toss the truck into neutral and brake, not well though.

opening the door won't do it unless you are less than 2 mph and your seatbelt is off, then it will brake and put the truck into park.

 

[cj7]

In the old days, the parking brake was cable operated and independent of the hydraulic brake system. Some cars had separate parking brake shoes, while others just pressed or pulled the hydraulic brake friction material.

The electronic parking brake pressurizes a couple of the hydraulic brake circuits.

If your hydraulic brakes go out, due to a leak, and the pedal goes to the floor, whether the e-PB does you any good depends on where the leak is. These days, most cars have four circuits, so a single leak (other than at the manifold) will only have a limited effect. Even after all the reservoir fluid is gone, there will be enough in the non-leaking lines to get you stopped. So, the odds that the regular brakes don’t work, but the ePB does, are low.

Ironically, your more likely to have a disabling electrical failure...

 

[mikeru82]

I'm old school. Never had a vehicle with an electronic park brake. In all of my old vehicles, if the brakes went to the floor, you press the emergency brake to help stop, instead of getting in a wreck.

How does this work on my truck? Can you just press the button, or open the door to trigger it?

Calling them an "emergency brake" is a misnomer. They are and have always been for keeping the vehicle from moving while parked. And are called parking brakes. Even on old school vehicles, most parking brakes would quickly fail if you tried using one in an emergency stop situation. Many of the parking brakes on larger trucks consisted of brake shoes that surrounded a drum attached to the drive shaft. And have been the cause of many fires when the driver forgets to release it before driving (ask me how I know LOL). There are some parking brake designs that would hold up. So I'm not saying all of them would fail. But they certainly weren't designed to be an emergency braking system.

 

[piening2150]

I'm old school. Never had a vehicle with an electronic park brake. In all of my old vehicles, if the brakes went to the floor, you press the emergency brake to help stop, instead of getting in a wreck.

How does this work on my truck? Can you just press the button, or open the door to trigger it?

 

[piening2150]

In the old days, the parking brake was cable operated and independent of the hydraulic brake system. Some cars had separate parking brake shoes, while others just pressed or pulled the hydraulic brake friction material.

The electronic parking brake pressurizes a couple of the hydraulic brake circuits.

If your hydraulic brakes go out, due to a leak, and the pedal goes to the floor, whether the e-PB does you any good depends on where the leak is. These days, most cars have four circuits, so a single leak (other than at the manifold) will only have a limited effect. Even after all the reservoir fluid is gone, there will be enough in the non-leaking lines to get you stopped. So, the odds that the regular brakes don’t work, but the ePB does, are low.

Ironically, your more likely to have a disabling electrical failure...

I just looked this up thinking 'surely that can't be right. It must be a separate electromechanical system... just to be safe'. But I'll be damned if you weren't right. It just activates the hydraulic brakes with the ABS module. Learn something new every day!

 

[Drewster]

Calling them an "emergency brake" is a misnomer. They are and have always been for keeping the vehicle from moving while parked. And are called parking brakes. Even on old school vehicles, most parking brakes would quickly fail if you tried using one in an emergency stop situation. Many of the parking brakes on larger trucks consisted of brake shoes that surrounded a drum attached to the drive shaft. And have been the cause of many fires when the driver forgets to release it before driving (ask me how I know LOL). There are some parking brake designs that would hold up. So I'm not saying all of them would fail. But they certainly weren't designed to be an emergency braking system.

Yup. I was going to say, you would think an "old school guy" would've tried out the parking brake at speed before making that assumption. Best case scenario you've got two flat-spotted rear tires and you reduce the collision speed by 5-10 mph, worst case scenario you spin and create a much more violent but exciting collision.

Seriously, as someone who has had brake failure, the only nice thing of a manual e-brake is that it's easier to modulate as you crawl toward a parking lot.

On modern cars, your best bet in most situations is to keep pressure (keep your foot down or keep pumping if it goes to the floor) in the system so the emergency systems can do their job.

 

[bucolic]

Calling them an "emergency brake" is a misnomer. They are and have always been for keeping the vehicle from moving while parked. And are called parking brakes. Even on old school vehicles, most parking brakes would quickly fail if you tried using one in an emergency stop situation. Many of the parking brakes on larger trucks consisted of brake shoes that surrounded a drum attached to the drive shaft. And have been the cause of many fires when the driver forgets to release it before driving (ask me how I know LOL). There are some parking brake designs that would hold up. So I'm not saying all of them would fail. But they certainly weren't designed to be an emergency braking system.

Well, all I know is I had an old Honda back in the day that had that Parking brake lever between the seats. You pulled it up to lock and then pressed a button on the end to disengage. Had a smart a** buddy who liked to yank that thing up at speed and let me tell you it stopped the car. In a circle but it stopped up. Completely locked up one of the rear tires. I guess we all were stupid kids at some point but that really p****d me off. After a couple of times of him doing that he drove himself.

 

[theblet]

That makes sense about the electronic parking brake. Hope I never have to find out. Thanks yall

 

[saylor]

Well, all I know is I had an old Honda back in the day that had that Parking brake lever between the seats. You pulled it up to lock and then pressed a button on the end to disengage. Had a smart a** buddy who liked to yank that thing up at speed and let me tell you it stopped the car. In a circle but it stopped up. Completely locked up one of the rear tires. I guess we all were stupid kids at some point but that really p****d me off. After a couple of times of him doing that he drove himself.

friend of mine in a 2 door civic used to hang with me on my 3 wheeler those old civic hatchbacks were the shizzle

 

[jdmartin]

Well, all I know is I had an old Honda back in the day that had that Parking brake lever between the seats. You pulled it up to lock and then pressed a button on the end to disengage. Had a smart a** buddy who liked to yank that thing up at speed and let me tell you it stopped the car. In a circle but it stopped up. Completely locked up one of the rear tires. I guess we all were stupid kids at some point but that really p****d me off. After a couple of times of him doing that he drove himself.

I was going to post something along these lines as well. The old foot-pedal parking brakes were just that, because there wasn't any reasonable way to use that brake to modulate pressure, so if you were to just jam it in an emergency you'd lock up the rear drum brakes because that's what these were attached to, by cable. If you had a lever-operated hand brake, absolutely you can use it as an emergency brake though you are only working two wheels (generally the rear). I can bring my Miata to a full, fast stop using the hand brake and this is on 4-wheel disc brakes, and I can modulate pressure by keeping the lock button pressed in and pulling/letting up on the handle. In fact lots of racers will use this technique when racing these cars to drift corners.

As for the original question, it's not something I would stay up worrying about. As a few people have already mentioned these are really parking brakes on these trucks because they generally attach to a mini brake shoe on a drum, and there's not a whole lot of material there so you wouldn't be stopping the vehicle with what you're working with; on my Titan I burned up the parking brakes several times because I would forget they were on since I also always had hand parking brakes.

Speaking of total brake failure, I've had it twice. Once in my old GMC truck in the winter, coming down a hill towards a stop light. Pushed down on the pedal and it went completely to the floor, no return. There was a car waiting on a side street to turn right onto the street I was coming down, and I just cleared the front bumper of that car and the rear one waiting at the light, jumped a small culvert and came to a stop in the middle of someone's yard there at the light in the snow. It was like something from a movie except there wasn't any hooting and hollering afterward, only me trying to restart my heart . Other time was on my old van in my driveway, which is a hill as well. I had put a new caliper on and was finishing bleeding the brakes. Pedal was nice and tight so I pulled the chocks and started it up, put the pedal down and into reverse at the same time. Pedal all the way to the floor, van jumped my retaining wall backwards, landed in my neighbor's yard who is downhill from me and came to a stop a foot from his house. Only thing that saved me from rolling it was the trailer hitch that stuck in the ground like a javelin and turned the vehicle. In both cases it was a split pressure differential, which for those who don't know is this valve that both sides of the MC is hooked to and sends the fluid around to the different wheels. You almost couldn't imagine one guy could have *2* split differential valves in one lifetime, but there it is.

 

[theblet]

Wow what a story! I had brake failure on my old corvette when the master cylinder went out. I used the emergency brake in moderate fashion to get home. Worked like a charm.

 

[Fatherof3]

In the owners manual it says that if your brakes develop a leak you will get a message to service your brake system but your brakes will work as normal as it’ll use the ABS system .
As far as the parking brake pedal on the floor , I’ve used that to stop one of my old Fords for a good 2 hours to get home . You pull the release handle while you press the pedal . That will allow you to modulate the pressure .

 

[kapinallinen2]

Page 296 in the owners manual.
"If exceptional circumstances should make it necessary to engage the park brake while the vehicle is in motion, maintain upward pressure on the electric park brake switch for as long as engagement is desired. The BRAKE telltale light will illuminate, and a continuous chime will sound. The rear stop lamps will also be illuminated automatically while the vehicle remains in motion. To disengage the park brake while the vehicle is in motion, release the switch. If the vehicle is brought to a complete stop using the parking brake, when the vehicle reaches approximately 3 mph, (5 km/h) the parking brake will remain engaged"
And judging from this on page 297, the EPB is an electronic actuator not relying on the hydraulic system.
"When servicing your rear brakes, it may be necessary for you or your technician to push the rear piston into the rear caliper bore. With the electric park brake system, this can only be done after retracting the Electric Park Brake actuator. Fortunately, actuator retraction can be done easily by entering the Brake Service Mode through the Uconnect Settings in your vehicle. This menu based system will guide you through the steps necessary to retract the EPB actuator in order to perform rear brake service"