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  1. #21
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    Oct 2018
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    Quote Originally Posted by stock car driver View Post
    your a idiot congrats you made my ignore list, seen enough of your stupid posts on here, why not go get a hobby this isnt yahoo chat this is all but dead forum for help what was your last user name and the one before that and the one before that on here? bye bye felicia
    Continue to spread your misinformation. I could care less. Many thought Galileo an idiot. But, they were the idiots. You can't beat the laws of physics.
    Last edited by RaceEngineer; 06-06-2019 at 10:02 PM.

  2. #22
    Join Date
    Oct 2014
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    Walker, LA
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    Quote Originally Posted by RaceEngineer View Post
    Friction force is independent of surface area. If you decrease surface area, you increase pressure. Friction only is affected by coefficient of friction and normal force. You would need a different pad material to make a difference. Unless you made the area small enough to overheat the pad. Then it would not make a difference until the pad was cooked.
    I was digging for information when I came across this thread and thought I might put my 2 cents in to help clarify differing opinions on this subject. I would agree that the smaller pad surface area would increase the pounds per square inch distribution of the actual brake caliper pressure at the brake pad contact point, on the rotor. But does that actually increase, or decrease the actual braking force for that rotor? I would think that reducing the surface area (friction area) would reduce the friction, causing less braking force for that rotor. An example of reducing friction area: (perfect world scenario) Car has 4 tires that are 10 inches wide that are all equally loaded, creating the same amount friction, or grip, when corning. Everything still the same, now change one of the tires to a 5 inch wide tread. That tire has a reduced surface/friction area. This reduction of friction area is a reduction of grip for that corner of the car when cornering. The same should happen if you reduced the friction surface of a brake pad. Less friction......Just my 2 cents...
    Our Creed: "Where two or more are gathered, there shall be a RACE!"

  3. #23
    Join Date
    May 2007
    Location
    Batavia, OH
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    12,391

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    Quote Originally Posted by turtle1hp View Post
    I was digging for information when I came across this thread and thought I might put my 2 cents in to help clarify differing opinions on this subject. I would agree that the smaller pad surface area would increase the pounds per square inch distribution of the actual brake caliper pressure at the brake pad contact point, on the rotor. But does that actually increase, or decrease the actual braking force for that rotor? I would think that reducing the surface area (friction area) would reduce the friction, causing less braking force for that rotor. An example of reducing friction area: (perfect world scenario) Car has 4 tires that are 10 inches wide that are all equally loaded, creating the same amount friction, or grip, when corning. Everything still the same, now change one of the tires to a 5 inch wide tread. That tire has a reduced surface/friction area. This reduction of friction area is a reduction of grip for that corner of the car when cornering. The same should happen if you reduced the friction surface of a brake pad. Less friction......Just my 2 cents...
    Tires are a much more complex system than a simple friction calculation. You changed the spring rate, the ability to channel debris out from under the tire, the number of edges in contact with the ground (edges and surfaces have different friction values) and a million other things.

    The only way you change pad size and affect braking power is if you remove material from the outside only (reduce the effective diameter of the rotor) or reach a higher operation temperature that then reduces the coefficient of friction.

    The calculation of friction force is simply coefficient of friction times normal force. That's it. No areas are involved. The first measurement to come into play is distance from center of rotation to center of brake pad. This is because now your force is applied at a distance. This is a torque stopping the wheel.
    Last edited by MasterSbilt_Racer; 01-23-2022 at 08:54 AM.
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    Droop isn't the problem.

  4. #24
    Join Date
    Oct 2014
    Location
    Walker, LA
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    77

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    Quote Originally Posted by MasterSbilt_Racer View Post
    Tires are a much more complex system than a simple friction calculation. You changed the spring rate, the ability to channel debris out from under the tire, the number of edges in contact with the ground (edges and surfaces have different friction values) and a million other things.The only way you change pad size and affect braking power is if you remove material from the outside only (reduce the effective diameter of the rotor) or reach a higher operation temperature that then reduces the coefficient of friction.The calculation of friction force is simply coefficient of friction times normal force. That's it. No areas are involved. The first measurement to come into play is distance from center of rotation to center of brake pad. This is because now your force is applied at a distance. This is a torque stopping the wheel.
    As far as the example of the tires, we could have used asphalt slicks to simplify the variables involved. I was just trying to find another subject matter as an example, to resemble a reduction in surface area. With your statement about the reaching a higher operating temperature, made me put thought into the tire surface area theory. That smaller tire will have grip, till you push it hard enough that it will start over heating compared to the other 3 tires. Once overheated, that is when it will not have the same grip. Thank you for your input, that had me put some thought into the "cause and effect" for the loss in grip. I also understand your point about removing pad material to simulate a smaller diameter rotor and I agree with that. That will reduce the brakes "leverage" that would be applied to the rotating wheel and tire. I guess it boils down to, if you want to reduce RF braking force, 1) you need have a smaller rotor diameter, to reduce the leverage, 2) you need a smaller caliper piston, to reduce the clamping force applied to the RF rotor, 3) you could use a RF proportioning valve, to reduce the line pressure going to the RF caliper, 4) a less aggressive pad material on the RF compared to the other pads being used. Am I forgetting anything??
    Our Creed: "Where two or more are gathered, there shall be a RACE!"

  5. #25
    Join Date
    May 2007
    Location
    Batavia, OH
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    Quote Originally Posted by turtle1hp View Post
    As far as the example of the tires, we could have used asphalt slicks to simplify the variables involved. I was just trying to find another subject matter as an example, to resemble a reduction in surface area. With your statement about the reaching a higher operating temperature, made me put thought into the tire surface area theory. That smaller tire will have grip, till you push it hard enough that it will start over heating compared to the other 3 tires. Once overheated, that is when it will not have the same grip. Thank you for your input, that had me put some thought into the "cause and effect" for the loss in grip. I also understand your point about removing pad material to simulate a smaller diameter rotor and I agree with that. That will reduce the brakes "leverage" that would be applied to the rotating wheel and tire. I guess it boils down to, if you want to reduce RF braking force, 1) you need have a smaller rotor diameter, to reduce the leverage, 2) you need a smaller caliper piston, to reduce the clamping force applied to the RF rotor, 3) you could use a RF proportioning valve, to reduce the line pressure going to the RF caliper, 4) a less aggressive pad material on the RF compared to the other pads being used. Am I forgetting anything??
    I think you have summarized the situation perfectly. Any would work. It's what can you get away with, within your rules.
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    Droop isn't the problem.

  6. #26
    Join Date
    Jul 2007
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    3,190

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    When I went to a modified I cryo treated my rear rotors to try and get some longevity out of them and they became worthless, zero braking..

    So after that I cry treated my rf rotor to reduce braking on that corner coupled with organic pads that rotor would be cold compared to the other 3.

    my rules didnt allow 3 wheel brakes

    Just another fyi to share.

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