Race Brake Pads On Street
Published: August 31, 2016; updated: December 8, 2016
Have you ever wondered what would happen when race brake pads are used on the street? In this tech installment I provide facts based on real experience, not conjectures.
Spoiler alert: it's great!
The biggest scare of running racing brake pads on the street is that they will not stop the car when cold, because racing brake pads are designed to operate at much higher temperatures than street driving normally sees.
I don't know if this was true for most track brake pad compounds at some point years ago but modern racing brake pad compounds can easily have more cold bite than street brake pads. In my personal experience, Raybestos ST-43 and ST-45 compounds had more cold bite than the mystery street brake pads on my Miatas. They also have more cold bite than brake pads on my truck and van.
Does this mean any race pad will have a higher level of cold friction than any street pad? No, in fact I felt that ST-45 were lacking in bite on the street. I think a "medium friction" track pad performs great on the street on Miatas, with "high friction" pads being worse. However even "high friction" track pads compare favorably to low cost local auto parts store/RockAuto/"lifetime warranty" brake pads in first stop and subsequent stops' bite.
An easy way to check a brake pad's cold bite is in the morning of a track day when the car and brake pads are, naturally, cold. How is the car decelerating relative to what one might expect from street brake pads? I know that in my cars I don't need to warm up the brakes when I start track sessions.
The second concern with running racing brake pads on the street is high rotor wear. Here is what I know:
On track cars rotors are discarded because they crack, not because they reach minimum thickness. In turn, rotors crack from heat cycles into high temperatures that street driving would never see. Even if cold braking with race brake pads uses the rotors more than hot braking, I find it unlikely that the overall lifetime of rotors will be affected by street driving, at least for cars that are primarily driven on the track and occasionally driven on the street. A car that is driven at a leisury pace 5 track weekends in a year and is street driven the balance of the time might indeed see elevated rotor wear.
At least some manufacturers of brake pads offer pad compounds that are very gentle on the rotors. Raybestos and PFC are two such manufacturers. In fact, I would often take rotors grooved by Hawk pads or running against the backing plates of completely worn out brake pads, put new Raybestos pads on, and watch the rotor surface get flattened smooth. Hawk pads are known for being hard on rotors, but they are not the only option these days.
Brake pads are probably the fastest wearing item in a racing brake system used on the street. That said, they also are the part that does the work. Personally I like having good brakes on the street car, and running racing brake pads puts a smile on my face when I street drive my Miata.
I have been advised that Raybestos pads in particular crack in street use. I experienced chunking which may be a consequence of cracking, but then "cracking" can mean a single crack resulting in a chunk or uniform cracking throughout the friction surface. I do not recommend running Raybestos pads on the street but for now I will continue to do so because changing brake pads requires time I do not have and I prefer Raybestos pads on the track.
Racing brake systems are not generally designed to be quiet, and some squealing is to be expected. Depending on its amount it can be anywhere from barely noticeable to annoying. I found that having all brake components in good shape - brake pads properly bedded, rotors flat and without pad deposits, wheel bearings in good condition - minimizes noise from the brake system.
Race brake pads often dust quite a bit. I can see brake dust on my street wheels after several days of street driving the car.
Raybestos brake dust apparently is rain-soluble - after driving in the rain for a few hours the wheels look much shinier than they did before, it looks like most of the brake dust is gone.
Should you run racing brake pads on the street? Ultimately the decision is yours. All I can say is that based on real life experience, racing brakes which are well matched to the car may work great on the street.