That's it! The rub you feel will not go away when driving. Of course I talking about a recent application!! Does one need brakes while not driving?

 

I routinely drive 4 hours without application of brakes.
I routinely drive over 100,000 miles without replacing brake pads.

Get real man! Or fix your car(s). ( or at least quit posting myths )

 

It is my understanding that in a hydraulic based system, the introduction of a new force is required to cause movement/pressure change within the system. Absent a new force, the system reaches equilibrium.

In a disc brake system the two main sources of force within the system appear to be the brake pedal (pressurized ABS system in the case of the FEH) and the rotor. The run-out/wobble in the rotor pushes the pads/pistons off the rotor while the brake pedal (or ABS system in the FEH's case) is what pushes the pistons/pads toward the rotor.

In your scenario, what pressure exist to constantly push the pads back on to the rotor?

At best, there is an occasional bump as the pad and the highest spot of the rotor collide but constant contact goes against the nature of the hydraulic system.

For a real world case study, I suggest we look at the behavior of the commonly used metal brake pad wear indicators that squeak or chirp when they contact the rotor after sufficient pad friction material has worn away. By design, during brake application, the arm/pad touches the rotor and an audible noise is created. Once the brake is released the audible noise quickly goes away as the vehicle returns to motion. The explanation for this is that the pad and the connected wear indicator arm is no longer in contact with the rotor surface. It has been pushed back from the rotor due to the run-out/wobble in the rotor and will do not regain contact until brake pressure is re-applied.

 

Look at this article, just scroll down to Pad Wear and Piston Movement or read it all: http://www.alcester-racing-sevens.co...brake_pads.htm

I've had two Ford products and never heard the so-called wear indicators, only the grinding sound when metal hits metal!

Pressurized ABS system in the case of the FEH?? What are you talking about? The HCU(hydraulic control unit) that on every FE too? The electric vacuum pump the the FEH has to supply vacuum to the brake booster when your in EV mode?

 

Well said Chris. ( MyPart )

You did a much better job saying what I was trying to say.
I know what you mean about the wear "squealers".
Great example.

 

Are you saying you've never heard of any vehicle using the wear indicator I described? Here's a link with a picture.
http://auto.howstuffworks.com/auto-p...isc-brake4.htm

Either way, this doesn't change the way this system works as an alert and how it proves that the pads and wear indicator arm are eventually moved away from the rotors by run-out/wobble.

In the FEH, most of the normal braking hydraulic braking force is generated by a hydraulic pump which is run to energize the high pressure accumulator, you can hear this unit pressurize as you open the door to get in the FEH (before Key-ON) and you will hear it depressurizes if you hang around long enough after getting out of the vehicle (after Key-Off).

I suggest you read the first page of this article to familiarize yourself with the FEH braking system. http://www.sae.org/automag/techbrief...-112-12-20.pdf

I don't know much about the standard FE (as I don't own one) but I'm 100% sure that the two different models have different braking methods.



You neglected to answer my question regarding what force exist to counteract the run-out/wobble force that pushes the pads off the rotor. Care to do that now?

 

I not saying that I've never heard about the wear indicators! I never "heard" the sound, only the sound of metal to metal contact. The pad was gone. Understand now?

The article is from 2004 and not really a Ford article. I have all the '09 Ford books, only the electrcal diagrams are different for the FEH. There is no mention of any high pressure accumulator. It could be that the system has changed since then but I do remember reading here about the noise you hear but not what it was.

I have on-line access to all the manual and will look at the 2004 later.

There isn't a force that counteracts, pressure is removed but the pads till touch lightly enough to feel. Disc brakes are open to the elements, if they retracted, it would leave a gap for anything to get between it and rotor(disc).

EDIT:
First Hybrid was in '05, the high pressure accumulator system was used through '07 and changed in '08, no high pressure accumulator mentioned. It does mention the sound it makes when opening the door too.

 

This Wptski "Doesn't Care" so it seems... It's right there on every post.

Talking to him is like talking to a brick...

He doesn't get it, doesn't care. So why should we???

 

Name calling again! Shows you lack proper education, upbringing and/or have mental problems.