All brake pads sold in the United States are supposed to have a DOT rating for friction stamped or printed on the pad. If you understand these ratings you can be sure you are choosing a pad that meets your standards for performance.
How do DOT friction ratings work?
DOT friction ratings are expressed alphabetically, starting at C for the lowest friction. As you go down the alphabet, the friction increases. G friction is higher than E friction, for instance. You will notice that the rating uses TWO letters. These indicate the Cold and Hot ratings, which are at 250F and 600F respectively. Some pads carry the same rating cold and hot, but some do not. Much of this has to do with the pad composition – organic pads, for example, usually carry a higher cold rating than hot rating. Notably, a pad with a rating that goes from high friction to low friction indicates a pad that will experience brake fade, i.e. the pad performance decreases when it gets hot. Pads with a lower friction rating when cold versus when hot will be missing some initial “bite” but will perform well when pushed hard.
What is a typical, or typically good rating?
Economy pads that you might find at your local parts store usually carry an EE or EF rating. These pads will work fine for most vehicles and most drivers, but those looking for the best in braking performance will want to look for a minimum FF rating, GF or even better FG rating. Premium pads are available with even higher ratings, like FG or even GG at the high end.
How high do the ratings go?
We mentioned that some of the very best on-road pads have GG friction ratings, and that is the highest friction rating available for on road pads. Race pads can carry HH ratings or higher, but typically are not recommended for on-road use. To get friction so high, HH pads have large downsides, whether it be cost or pad life. Many HH pads are part of a carbon pad-carbon rotor setup in very high end supercars. HH race pads are usually designed for single-race use – meaning they get replaced as soon as the race is over. Outside of supercar territory, we don’t know of an HH rated pad that is recommended for street use.
Want to get into the weeds?
Now that you understand the basic principle, we can get into specifics for what each code actually means.
|Rating||Coefficient of Friction|
|E||.25 – .35|
|F||.35 – .45|
|G||.45 – .55|
|H||.55 – .65|
You can see there is a big difference between E rated pads and G rated pads, so it is worthwhile to investigate the friction rating of the pads you are looking at before installing them in your vehicle.
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