pad, rotor combo?
#2
05-24-2005, 02:11 PM
I guess you didn't get a timely response from anyone, but here's my $ .02. Brembo and Hawk sound good to me, but I'd go with the slotted Brembos, not the drilled (hope this suggestion didn't come too late).
I am in the process of replacing rotors and pads on my '97 4WD Expedition, and my research suggests that more expensive, high-tech pads wear better, operate properly under a broader range of temperatures, more effectively insulate the caliper from heat, and cause less wear on the rotors, not more. The reason given for the latter feature is that high tech pads heat the rotor more evenly at a molecular level, distributing the braking friction evenly over the entire surface (at the mollecular level) and placing less localized stress on any given point at any given moment. Unless someone suggests a reason why this explanation is mistaken, I'm buying into it.
Aside from the foregoing considerations, using longer-wearing pads will almost always increase rotor life. For the brakes to work properly, the rotor MUST be surfaced each time the pads are replaced. Surfacing removes material, making the rotors thinner, and so, the more often the pads are replaced, the more quickly the rotors will reach the point at which they must be replaced due to material removal.
I believe that drilling holes in rotors is dangerous without a great deal of sophisticated research into metalurgy and other factors affecting the strength and heat response of cast metal parts. The holes provide gas and dust vents, but they also reduce the amount of metal available to absorb heat and the surface area of the rotor available to the pad under ordinary operating parameters. Moreover, the holes can seriously degrade the structural strength of the rotor and create weaknesses that potentially lead to catastrophic failure.
According to the Brembo engineers, drilled and slotted rotors improve braking only in high stress applications (e.g., racing and towing). For the first stop from 60 or 80 mph, OEM rotors will perform as well because the properly maintained system will remain well within the design temperature range. Further, in modern ABS-equipped vehicles, the stopping distances are ordinarily limited by the tires and/or road conditions, not the brakes.
From my research, I conclude that if I want more stopping power in my Expedition, my only choice would be to invest in a $2,500 wheel and tire upgrade and a $3,500 front rotor and caliper upgrade -- and it appears that tires having a friction coefficient sufficient to make use of the brake upgrade would wear out in 10,000 miles under ordinary driving conditions.
Ford and GM and Daimler Chrysler invest billions in R & D, and while they have economic considerations, if there were something as simple and cheap ($5) as drilling holes in the rotors that would make a significant difference in real-world driving, you can bet they would do it -- for the sake of competition, if nothing else. In any event, I now question whether aftermarket companies really have the resources to do the type of research required to improve most OEM braking systems.
Everything is a trade-off. For example, bigger rotors are not necessarily better. Bigger rotors that are also more massive could prevent the brake pads from reaching the temperature at which they operate best. Also, the rotational intertia of more massive rotors could degrade braking, and the additional unsprung weight could degrade the suspension's competence to handle braking on less-than-even surfaces.
Alas, it appears that I will not be able to transform the Expy's brake system into a sports car. I will be grateful for any and all comments, repartee, argument, or even bona fide information.
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I am in the process of replacing rotors and pads on my '97 4WD Expedition, and my research suggests that more expensive, high-tech pads wear better, operate properly under a broader range of temperatures, more effectively insulate the caliper from heat, and cause less wear on the rotors, not more. The reason given for the latter feature is that high tech pads heat the rotor more evenly at a molecular level, distributing the braking friction evenly over the entire surface (at the mollecular level) and placing less localized stress on any given point at any given moment. Unless someone suggests a reason why this explanation is mistaken, I'm buying into it.
Aside from the foregoing considerations, using longer-wearing pads will almost always increase rotor life. For the brakes to work properly, the rotor MUST be surfaced each time the pads are replaced. Surfacing removes material, making the rotors thinner, and so, the more often the pads are replaced, the more quickly the rotors will reach the point at which they must be replaced due to material removal.
I believe that drilling holes in rotors is dangerous without a great deal of sophisticated research into metalurgy and other factors affecting the strength and heat response of cast metal parts. The holes provide gas and dust vents, but they also reduce the amount of metal available to absorb heat and the surface area of the rotor available to the pad under ordinary operating parameters. Moreover, the holes can seriously degrade the structural strength of the rotor and create weaknesses that potentially lead to catastrophic failure.
According to the Brembo engineers, drilled and slotted rotors improve braking only in high stress applications (e.g., racing and towing). For the first stop from 60 or 80 mph, OEM rotors will perform as well because the properly maintained system will remain well within the design temperature range. Further, in modern ABS-equipped vehicles, the stopping distances are ordinarily limited by the tires and/or road conditions, not the brakes.
From my research, I conclude that if I want more stopping power in my Expedition, my only choice would be to invest in a $2,500 wheel and tire upgrade and a $3,500 front rotor and caliper upgrade -- and it appears that tires having a friction coefficient sufficient to make use of the brake upgrade would wear out in 10,000 miles under ordinary driving conditions.
Ford and GM and Daimler Chrysler invest billions in R & D, and while they have economic considerations, if there were something as simple and cheap ($5) as drilling holes in the rotors that would make a significant difference in real-world driving, you can bet they would do it -- for the sake of competition, if nothing else. In any event, I now question whether aftermarket companies really have the resources to do the type of research required to improve most OEM braking systems.
Everything is a trade-off. For example, bigger rotors are not necessarily better. Bigger rotors that are also more massive could prevent the brake pads from reaching the temperature at which they operate best. Also, the rotational intertia of more massive rotors could degrade braking, and the additional unsprung weight could degrade the suspension's competence to handle braking on less-than-even surfaces.
Alas, it appears that I will not be able to transform the Expy's brake system into a sports car. I will be grateful for any and all comments, repartee, argument, or even bona fide information.
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