Ceramic Vs. Kevlar Brake Pads
In the battle to eliminate the shortcomings of semi-metallic brake pads, two types of technology in brake pad friction compounds have emerged--Kevlar and ceramic--which are now being used to eliminate some of the problems of noise, wear, and dusting associated with traditional semi-metallic brake pads. Each of these pad compounds has shown itself to be an improvement, but each also has some weak areas.
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History
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Semi-metallic brake pads were developed to address the high heat generated by downsizing of disc brake systems in the 1980s. As a result, we began to see increases in brake rotor wear, excessive brake dust, and squealing (along with other noises). The buyers of these vehicles had serious problems with this, and technicians fought daily with these problems, specifically brake noise.
Kevlar pad compounds began arriving in the 1990s to address these problems. Made up of Kevlar and steel, this is still considered to be a semi-metallic pad, but the higher concentration of Kevlar significantly reduced noise. Lower dusting levels were also achieved, but wear remains a problem.
The latest ceramic seems to address all of these concerns. Dusting, excessive wear, and noise all appear to be a thing of the past. However, the downside to ceramic pads happens during cold weather. The first few stops of a ceramic pad-equipped vehicle show a decrease in braking efficiency. Once the pads are heated, this problem goes away.
Heat Range
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A comparison of heat range shows both Kevlar and ceramic pads to have a higher tolerance to heat then the factory semi-metallic pads. However, while the Kevlar pad does show an improvement in resistance to brake fade brought on by heat, it does not have the resistance to extreme heat and does not recover from that heat as fast as the ceramic pads.
Ceramic pads have the edge in terms of the ability to resist and recover from heat, because of the ceramic pads' superior ability to absorb and then quickly release heat. This prevents heat buildup, and brake fade. The downside happens during cold stops. The ceramic pad shows a decrease in braking efficiency until warmed up, and the first few stops are noticeably weak in terms of stopping force.
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Noise
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Noise characteristics are where ceramics shine. Because the ceramic pad compounds contain no steel fibers, the noise generated by these pads is beyond the range of human hearing.
Kevlar pads still contain steel fibers, although far less then traditional semi-metallic pads. This results in a reduction of noise, but not the total elimination seen with the ceramic pads.
Dust
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No brake pad is without dust. Dust is inevitably caused by wear of the pads and the rotors. Kevlar pads still have dusting problems, although those are reduced by the lower levels of steel. The ceramic pads still have dust as well but this dust is light in color, and resists sticking to parts like wheels because it isn't ferrous-metal based and there is less of it. When it comes to eliminating brake dust, the edge in performance goes to the ceramic pad.
Conclusions
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The Kevlar-based pads are a definite step up from standard semi-metallic pads, and have an edge over ceramics as far as cold weather stopping is concerned. However, the ceramic pad has a slight edge in almost every other concern.
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