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The brakes will grip, but you need to push harder on the brake petal. This is usually termed 'petal feel'. The brakes will still be able to lock up the wheels and the ABS then takes over, then your braking performance is really limited by tire patch traction, or your choice of tires and road surface/condtions. Many equate petal feel with braking performance, and I can't disagree with that as an objective. It just feels better.
Some pads have higher friction than others which provides a 'better petal feel'. New pads on new or used rotors can sometimes feel weak and soft. As the pad wears/beds-in the petal feels more solid and the friction and petal feel improve. The surface of a new pad has been 'machined' and that surface is a but torn up and rough. With heat, pressure and wear, the suface consolodates and the spongy feel goes away. This can be a real issue sometimes and as a result, when front and rear brakes are done as the same time, the result can feel really bad. Sometimes folks think that their is then air in the system and bleed the brake lines, that that solves nothing, but is a good maintenance thing to get done anyways.
New pads on old unmachined rotor can feel soft as the rotor probably is not flat or smooth and the pad needs to wear to fit or bed into the shape of the rotor surface.
There are two types of pads, basic friction-abrasive action and coheasive. The black dust on your wheels is not just the pads, but iron from the rotors. Kelvar and other organic rich pads transfer a thin film of organic material to the rotor. When the brakes are engaged, the pad friction has some coheasive action with the organic material making and breaking molecular bonds. That action is something that you could call sticky. The EBC pads are like this. However, the EBC and other pads of this type have metal particles in them and other materials of a classic abrasive nature to create a balance in the organic film on the rotor. If that film gets too thick or uneven, things can go bad. An uneven film, though invisible to the eye, will feel like a warped rotor, when the rotor is true. And if the rotor is left/ignored like that, the uneven heating of the uneven braking will probably create a thermal warp. But for someone who understands what is going on, this condition can be totally eliminated by a lot of hard stops over a few days that burn off the deposit on the rotors. But that is a lot to expect many owners to understand or care about. So i cannot recomment EBC pads for everyone. For those who brake aggressively there is enough heat to keep the organic content of the pad surface burnt off sufficiently to avoid that problem. And new pads should be burnt in to improve petal feel and to condition the exposed organics. What can happen, is someone who does a lot of calm braking over an extended period of time, the pad wears down to expose an organic rich surface that has not been condtioned by the heat of sufficient aggressive braking. The they are at highway speeds and a traffic condition has them breake hard and briefly. That can create an uneven transfer of organics from the pad to the rotor. So as I said, perhaps too much for many drivers. But for those who take advantage of a performance pad and brakes hard during their normal driving, the EBC pads to work very well. But I cannot call them trouble free.
EBC has changed the pads, they now all come with shims which is new, and the top surface of the pad has a wearing in layer that is meant to improve the pad to rotor interface. But I can't see the point of that except for new pads on old rotors(no machined). And the pads have chamfered leading and trailing edges in an effort to make them run quieter.
Ceramic brakes... Well anyone who adds some ceramic fibers to their pad compound, or a ground up flower pot, can technically call the product ceramic, because there is no definition of what such a thing is. All pads are a mixture of things. Kelvar pads are not blocks of plastic and ceramic pads are not solid blocks of ceramic. So you can't make any generalizations about pads by the words used to market them. The pad compounds are a brew of things and 'trade secrets'. There is no real formula for working these things out, and the method involves a lot testing of different mixtures of things, sort of like working things out in the kitchen.
Do not think that anything that you have heard about exotic ceramic materials from space science or ceramic or carbon/carbon rotors on exotic race cars has anything on common with ceramic brake pads. (Some race cars have exotic rotors that run extremely hot and get white hot, these then reject very large amounts of heat via radiation heat transfer. Normal iron brake rotors get hot, but only warm in comparison, and the heat loss is mostly by conduction to the air.) Ceramics in brake pads are just another substitute for what asbestos fibers used to do.
When you work on brakes, after fitting the pads/rotors, you need to pump the brakes to advance the pistons. NEVER push the brake petal to the floor. This can damage the cup seals in older master cyliders as the extremes of the MC bore where the pistons and seals never usually go can be rough with corrosion deposits (rust) that will cut the soft cub seals. Put a block of 2x4 behind the petal to limit strokes when bleeding the brakes etc.
, Thu, 17 Feb 2005 15:52:23
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