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Ok, guys, just read an interesting message from a fellow discussing braking techniques going down steep grades. I have always applied my brakes, slowed down, then let off. This fellow suggests you should keep your foot on the brakes all the way down the grade. He suggests that this actually keeps the brakes cooler than pulsing. IF this is true, then I have been using the wrong techniques and am overheating my brakes. What technique do you use? IF possible, present some hard evidence on brake temperatures if you can.
 

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I think i read the same post you did. I can't disagree more with the steady pressure technique.

Think of running down stairs with your hand on the rail. Or holding onto an escalator rail. If you grip tighter for a moment, then release, your hand will cool. If you grip lightly, but consistently, your hand will soon be so hot from friction that you'll be forced to let go.

Braking (speaking of rotors/pads here) is all about converting kinetic energy (your truck trying to follow newton's 1st law) into heat energy via friction. The ability of your brakes to transfer heat is core to their ability to stop your vehicle.

You have to balance heat transfer with heat retention. Ceramic brake pads (and rotors, though I don't think anyone makes the latter for the f150) are excellent for heat transfer. Heat gets into them and is quickly transferred out, with no retention. However, for light duty, they tend to feel weak until they warm up.

Regular pads warm up quickly, and achieve operating temp quickly, because they have a higher heat retention, and they don't transfer heat as efficiently. I know that sounds a little counter intuitive, because you might think "they get hot - of course they're transferring heat". But what they're doing is *storing* heat. In general, a full ceramic setup of pad and rotor will cool from glowing red to cool to the touch in less than 15 seconds. A regular asbestos pad and iron rotor will take 10 mins.

Now, dispersing that heat is usually the responsibility of the rotor. That's why they're usually vented. Also, the larger they are, the more heat they can store, and the larger cooling area available.

Next, when a rotor and pad heat up enough, they start outgassing. This means that between the two friction surfaces, a thin layer of gas actually boils off, reducing friction. Very much like a hovercraft. This is what "brake fade" is. There are various methods employed to try to evacuate this gas, including slotting and cross drilling.

Having said all that, it comes down to "a cool brake is a functional brake", and having a steady pressure on the pedal means the brake never gets time to cool down. It would work at slow speeds, because you're not converting enough kinetic energy, but not higher.

Sent from my SGH-I747M using Tapatalk 2
 

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I think i read the same post you did. I can't disagree more with the steady pressure technique.

Think of running down stairs with your hand on the rail. Or holding onto an escalator rail. If you grip tighter for a moment, then release, your hand will cool. If you grip lightly, but consistently, your hand will soon be so hot from friction that you'll be forced to let go.

Braking (speaking of rotors/pads here) is all about converting kinetic energy (your truck trying to follow newton's 1st law) into heat energy via friction. The ability of your brakes to transfer heat is core to their ability to stop your vehicle.

You have to balance heat transfer with heat retention. Ceramic brake pads (and rotors, though I don't think anyone makes the latter for the f150) are excellent for heat transfer. Heat gets into them and is quickly transferred out, with no retention. However, for light duty, they tend to feel weak until they warm up.

Regular pads warm up quickly, and achieve operating temp quickly, because they have a higher heat retention, and they don't transfer heat as efficiently. I know that sounds a little counter intuitive, because you might think "they get hot - of course they're transferring heat". But what they're doing is *storing* heat. In general, a full ceramic setup of pad and rotor will cool from glowing red to cool to the touch in less than 15 seconds. A regular asbestos pad and iron rotor will take 10 mins.

Now, dispersing that heat is usually the responsibility of the rotor. That's why they're usually vented. Also, the larger they are, the more heat they can store, and the larger cooling area available.

Next, when a rotor and pad heat up enough, they start outgassing. This means that between the two friction surfaces, a thin layer of gas actually boils off, reducing friction. Very much like a hovercraft. This is what "brake fade" is. There are various methods employed to try to evacuate this gas, including slotting and cross drilling.

Having said all that, it comes down to "a cool brake is a functional brake", and having a steady pressure on the pedal means the brake never gets time to cool down. It would work at slow speeds, because you're not converting enough kinetic energy, but not higher.

Sent from my SGH-I747M using Tapatalk 2
Thanks for all the information. I was "uneasy" reading the other thread that suggested steady pressure as the best downhill braking approach. I'm glad to hear that there are at least two schools of thought. I'm too old to change ;)
 

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Discussion Starter #4
ya - me too!:p
 

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All depends on the situation your in and what load you have.
 
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