One of our company trucks, 07 F150, just got a hole in the flex brake line to the drivers front brake.
The pedal goes all the way to the floor in 1 pump. We thought this was weird, seems like in 1964 or something the feds required dual chamber master cylinders. We were told that these trucks do not have this, no back-up.
What is with this??? I guess its good its not a Toyota with the gas pedal stuck at the same time!!

Is this right?

 

Pretty sure this is normal....bust a brake line and you'll have virtually no brakes.....thats what the e-brake is for

 

You still have a dual circuit brake system, probably diagonally split, meaning your RF and LR tire are on one circuit, and your LF and RR tire are on the other. Keep in mind you just lost 50% of your stopping force so you will have to push the pedal 2 times harder. I bet that the pedal does not completely go to the floor, but probably still comes close enough to scare you!

 

It's not called a gas pedal anymore. Once drive by wire became the norm the ECM took over control of acceleration not the driver. You only tell the computer how fast you "intend" to go and the ECM decides if it's OK for you to go that fast or not. If the answer is NO you can push as hard as you want and your intentions will not be followed. So it's now better to call it the "Driver Intent Pedal".
The problem Toyota has is extremely rare because of redundancy built into the system. The system is designed to be FAIL SAFE so multiple failures would have to occur at the same time for the vehicle to accelerate on its' own. It's designed to slow down or stop if a problem is encountered not to speed up. The one thing Toyota is doing wrong is to tell people not to turn off the key. I think I'd much rather steer and brake for a few seconds without power assist(key switch OFF) rather than try to drive a vehicle that is speeding out of control with the wife and two kids in it.

 

they would say do not because some would turn the key to lock and lock the steering.

 

If the car is in gear you can't turn the key all the way back to lock the steering wheel.

 

So, are you saying when the hose broke the driver had NO brakes?

He should have still had brakes on the rear. The brake system is still split into two circuits, each with it's own portion of the master cylinder piston. The front brakes are one circuit, the rear brakes are the other. If the pedal went all the way to the floor I'll wager the driver had already used the brakes a few times and pumped the reserviour dry.

On the older dual system master cylinders, the two had seperate reserviours, or rather it was split so. On the newer systems, you still have a dual braking system, each system has it's own part of the master cylinder activating it ... they just share the one reserviour now which is probably why someone told you what they did, they just weren't up on it.

We get used to a vehicle, used to where the brakes grab, then one day a hose blows and the pedal goes closer to the floor, feels like NO brakes but actually we still have the other end working ... just takes a longer stroke.

However, it is a problem that must be attended to before continued operation as you can pump the reserviour down.

Going way back, like to my '57 Chevy I had in HS, single systemm, all 4 brakes on one line, a hole anywhere and you had no foot brake. Better than old machanical brakes activated by cables still.


I saw the post above about them being split diagonally, but the Ford book says it's still split front / rear. A diagonal split would cause a severe pulling of the steering wheel right or left in a panic stop if a hose blowed.

 

Some will also drive it off the highway at 100 MPH as the state cop did with the wife and kids in the car killing everyone. If the key is turned OFF the vehichle is only going a very short distance before it stops especially if the brake pedal buried in the floor board even without power assist. You also have the E Brake and I believe this situation qualifies as an emergency. If I'm in a runaway Toyota I'm turning the key switch to OFF and putting the E Brake fully ON. I don't remember even hearing Toyota tell anyone to use the E Brake now that I think about what Toyota suggested people do in this situation. Why the heck have an E Brake if you're not going to use it in a situation like this?

 

Always seems odd to me when people refer to the state cop who was driving the Toyota when the acceleration problem took over.....................why didn't he put the car in neutral, turn the key off, and pull the e-brake? I would think a cop, who has had all kinds of driving training, would not have panicked. He even called 911 and spoke to them about the dilemma. I would hope in this type of situation I would have the presence of mind to positively react..................

 

In the time it took him to dial 911 he could have had the car stopped. Makes you wonder what kind of training he had for emergency situations. He must have slept through class that day. You expect the littly old lady with blue hair to panic in a situation like this, but not a highway patrol officier.

 

You're right. In the time he called 911, explained the problem and urged them to " pray for us " he could have turned the key off, put the car in neutral, and pulled the e-brake. Granted, he would have been coasting pretty fast, but going off the road onto the median could have slowed him down and saved their lives. I just don't get it...........

 

Yeah, that's what I thought. There must be a problem with the rear brake portion of the cylinder then. The reservior (single tank) still had alot of fluid in it. I personally stepped in the brakes and they hit the floor with no resistance. The front right brake line sprayed fluid.
He limped it to the shop from about 1 ile away where it let loose, his E brake cable had broken about a year ago and he never got it fixed.
Probably need to have the pressure tested in the rear circuit. I even asked him if he noticed the back brakes had lasted a real long time, he couldn't remember.
Looks like I better get on this now...............
thanks, Jeff

 

You never need a spare tire until you get a flat. You never need your E Brake until your hydraulic system fails.