I was 17 years testing and developing friction material and there are some weird and wonderful statements scattered through this thread. To start with, the thickness of the pad is determined by the space between the calliper piston and the rotor. The thickness of the CX-5 pad and backplate is 15.9mm and as a comparison, a RAV4 pad is 17.5. Thats 1.6mm or 1/16Ē. Thinner, yes but not enough to make the difference stated above.
Rates of wear are determined largely by temperature as that is what breaks the resin binder system down. The rate of wear is exponential so doubling the temperature wonít just double the rate of wear, it will be something more (could be double or triple) but they donít stay the same so repeating getting them hot might produce more wear and a long period of highway might reduce it. In choosing a friction material, vehicle manufacturers will look at hundreds of test results under a wide range of conditions. The emphasis on pad performance has changed and more recently it is based on performance and not life. Some vehicle builders are big on black dust and some ignore it. The main thing for most these days are; refinement - things like pedal feel, noise, creep groan (the groaning noise you get if you let the vehicle creep at the lights) etc. The legal demands for performance have gone through the roof so as I said, life is much less important and the vehicle manufacturers are usually content with life from 10,000 to 80,000 miles depending on duty and if the car sees very light use that might climb well up as some have experienced. Long life can have its own problems. Pads that wear quickly keep the rotor clean and true and the calliper enjoys work and will function best when the duty keeps the parts moving. Just like a garden gate that doesnít see use, it will start to seize up and make noises. The discs can start to corrode and they will suffer run out as a result of dirt and deposits of friction material spread unevenly on the surface.
Chris TH talks of these so called ďperformance padsĒ. There are many available but few are worth the money paid for them. To understand why you need to understand the pad construction. It is made up of roughly 60% fibre - this is the framework that holds it together and holds all the other ingredients in a random dispersion. There is then friction modifiers - lubricants like carbon reduce noise and stabilise performance, abrasives like zircon and silica increase friction. Some of these ingredients are active at different temperatures so provide stability performance throughout the range of working temperature. Finally, a resin system of some sort binds it all together. These are oil based and are what stink and smoke if you get the pad hot. Performance pads use various fibres from steel to man made fibres like rock wool and ceramics. Steel is cheap and is what is in the standard pads. It is very strong and withstands sheer force but it is corrosive and can cause the pads to stick to the rotor after rain or washing. To find an alternative you have to look at the man made stuff. Kevlar is good but about 40X more expensive than steel. Rockwool and ceramic fibre is made by producing a solid block then thrashing it to bits with rollers or shot. It then ďfibrillatesĒ like cotton candy and then it will function like steel fibre or the asbestos that has long gone. So what about these performance pads? A lot are nothing more than normal steel based pads but are baked longer or twice. This has the effect of super curing the resin and may provide some extra life and performance as the fillers are less likely to burn out. The man made fibres may give some benefit but not really that much. Clever marketing and fancy packaging help justify the cost and inspire the placebo effect just like some fuel additives. They also have a downside in that when longer baked or encapsulated in very durable fibre (you guys say fiber, right), they often donít perform very well at normal operating temperature. They might satisfy the ego of a normal road use enthusiast but they really donít justify the cost.
Why have they worn out quickly in the OPs CX-5? Probably because they been driven at a slightly higher duty level and because it may be one of the newer materials in the 2016 model that meets all the global requirements for braking. Mazda might swap them as a gesture but they arenít obliged to as they are considered normal wearing parts. Mine are about half worn at 8000 miles and I am completely satisfied as I cane them over the hilly route to work. As a result, my discs are dead true, I donít get noise and the callipers slide as free as a bird. Iíve already got a set of pads ready to pop in when the winter wheels come off in April. The cost the equivalent of $50 and Iím dead happy at that. The brakes on my Cx-5 are the best Iíve ever had on any car and when I hurtle down a 20% grade at 70mph I expect them to wear out. Stopping a ton and half at the bottom of that hill is absolutely effortless.