Shop Talk | The ABCs of Edge Codes

Next time you have a new set of brake pads in your hand take a look at their edges. You’ll see a series of numbers and letters that collectively are known as the “edge code.” The edge code contains specific information about the brake pad, including who made it, what type of material is used, and a description of the pad’s initial friction properties.

If you look at the first group of numbers and letters, you’ll see something like ABC 1234 XX. It’s those last two letters that are commonly misinterpreted. They are not, as some people seem to think, an indicator of the brake pad’s quality or its ability to stop the motorcycle so much as a description of how the pad will perform at different temperatures.

The first letter indicates how well the pad functions at “normal” temperatures, which the SAE defines as being between 200 and 400° F, and the second letter is how well the pad resists fading at between 450 and 650° F, as tested on something called a “Chase Machine.”

The edge codes run from C, which indicate a frictional coefficient of less than .015, to H, which has a coefficient of 0.55. The first letter here indicates the pad’s performance under normal temperatures, and the second, under high temperatures. A pad with an edge code of HH, for example, offers similar braking force whether it’s hot or cold, whereas one rated FH would have somewhat less bite cold than it does hot.

Confusion sets in because some people automatically assume that for a given set of pads, the higher the coefficient of friction, the more stopping power they’ll have. While there’s some truth to that, the pad’s true stopping power is predicated by the pad material, not its resistance to fade. In fact, most manufacturers will offer several different brake compounds, all with the same edge code rating, for use under differing circumstances.

The bottom line is that while edge codes are an important guide to choosing a particular pad, it's not the only thing, so never assume that simply going to a pad with a high edge code will improve braking. Picking the wrong pad could have dire consequences, ranging from prematurely worn pads and rotors, to an inability to stop the motorcycle—and that's as simple as ABC. CR