Centric Parts:
centricparts.com
(626) 961-5775
Hawk Performance:
hawkperformance.com
(800) 542-0972
Mazda:
mazdausa.com
Race Technology:
race-technology.com
Tire Rack:
tirerack.com
(888) 541-1777
Photography by Per Schroeder
Going skydiving? You’ll need a parachute. After all, it should make leaping from that airplane a bit more survivable.
Of course, not all parachutes are the same, and there’s more to them than different colors. Parachutes come in a variety of airfoil shapes and sizes, each one suited to a particular jumper and situation. While they’re all designed to serve the same basic purpose, there are subtle differences in the huge range of offerings.
You can think of brake pads in a similar way. Although there are countless varieties of pads available today, they all do the same thing: create friction to slow a car. Of course, the faster you go on track, the more important it becomes to have adequate stopping power.
High-performance brake pads are a crucial component for a car that sees open track time or race use. Not only are these top-tier pads more resistant to fade, but they can also have a higher coefficient of friction for quicker stops. Of course, that improved pad friction will only help if the tires are good enough to take advantage of the increased brake torque.
But what about autocross use? Are high-performance pads an advantage when battling the cones? While the brakes usually don’t get smoking hot during a 60-second autocross run, they can still see elevated temperatures, especially if there’s a co-driver adding a second dose of abuse.
More importantly, most of us autocross on sticker-than-stock tires. Can increases in brake pad performance help those grippy tires yield faster times?
To compare these theories against the stopwatch, we pressed our 2010 Mazda MX-5 project car back into service. To see how brake pads impact autocross performance, we tested four different brake compounds: the OE Mazda pad, the street-performance Hawk HPS, the track-worthy Hawk HP Plus and the race-ready Hawk DTC-60.
Our Mazda’s KW coil-over suspension and fat Dunlop Direzza Sport Z1 Star Spec tires make it a great platform for evaluating brake pads. The car is easy to drive, and we’ve found the Dunlops to be very consistent throughout the day and over a wide range of temperatures.
Tire Rack’s John Rogers and Chris Harvey served as our test pilots for this exercise. They’ve logged thousands of laps on Tire Rack’s own test course—which would again serve as our test lab—and have a considerable amount of seat time in the MX-5 project. A Race Technology DL1 data logger handled the data acquisition for the track work, while a Vericom VC2000 recorded the 60-to-zero stopping distances.
We tested each of the four pad compounds on a separate set of brand-new Centric rotors. By testing each pad with fresh rotors, we eliminated the possibility of contamination between samples.
Each set of pads was bedded in using the manufacturer’s recommended procedure. This included several stops from speed plus an appropriate cooldown period between sessions. The pads and rotors were then removed from the car and set aside until our day of testing.
We started with the stock Mazda pads and then, in order, went on to the HPS, HP Plus and DTC-60 compounds. We finished off the day by retesting the original pads; this is a great way to make sure the surface and conditions have remained consistent.
Each set of pads also went through the same test sequence, starting with four two-lap runs. Immediately after logging those laps, we did five 60-to-zero stops on a section of level asphalt.
The pads that originally came on the MX-5 feature a ceramic-based compound and are considerably better than the stock pieces of yore. Today’s ceramic material yields both good pedal feel and fade resistance without the typical increase in noise or dust.
Our drivers felt that the initial bite and stopping power of the OE pads were better matched to original tires than the high-grip Dunlops, however. “The OE pad requires moderate to heavy pedal pressure to get the braking effort needed to haul the car down from speed,” John noted.
Chris backed that up with a similar observation: “The Mazda pads exhibited the least initial bite and required the most effort to reduce speed throughout the brake application.” The bite, or lack thereof, indicated a lower-than-optimal coefficient of friction for our autocross application.
However, the stock pads didn’t have any real bad habits. Chris thought the modulation and pedal feel were not an issue at the limit. He also didn’t encounter any noticeable fade. “They were smooth, quiet and clean, as they went about their business without any drama,” he added.
John summed up the stock pad’s performance with some surprisingly kind words: “These pads provide moderate initial bite and have a very linear feel. The braking effort changes up and down directly in relation to pedal effort. Overall these pads have good brake feel, they just require lots of leg effort for peak deceleration.”
Hawk Performance HPS pads are seen as a step up the performance ladder from the stock pieces. These performance-minded pads are built from a carbon-based friction material, and according to the manufacturer they offer more stopping power with minimal increases in noise and dusting. They also have a higher heat range than most OE pads, making them suitable for high-performance street, autocross and light track use.
Both of our drivers noticed that the HPS pads delivered a nice increase in initial bite and stopping power over the OE pads. Chris applauded the HPS’s behavior: “These traits inspire driver confidence when pushing the car to the extremes of the performance envelope.” He found that the HPS’s quicker reaction time and stronger braking power better matched the modified MX-5. “The strong initial bite and flat brake torque curve is like a friendly handshake with the tires’ contact patch, allowing the driver to feel the limit without going unexpectedly beyond,” he noted.
John added that the HPS pads are also easier on the driver. “These take much less physical work on behalf of the driver to utilize all of their performance,” he noted.
The Hawk Performance HP Plus is a similar to its “little” brother in that it’s meant to be a multipurpose pad. However, the HP Plus favors higher heat capability at the expense of increased noise, rotor wear and dust. According to Hawk, the HP Plus is designed to be a track-capable pad that can manage the drive home. It’s also intended for the serious street and autocross enthusiast.
Compared to the HPS, the HP Plus delivered a significant jump in initial bite and considerably more stopping power. However, this newfound braking performance came with an unexpected result: Our drivers slowed too much and misjudged their braking points.
The excessive slowing was compounded by brake-torque ramp-up—as the car dove deeper into the braking zone, more braking power was generated without any increase in pedal pressure. “This trait initially led to over-slowing for the turn-in point, but was easy to adapt to,” Chris noted.
“This pad has a somewhat rising rate of friction,” John explained. “The braking force climbs gently even with no additional pedal pressure application. This instills confidence, as the braking effort is reassuring.”
Overall, both drivers enjoyed the HP Plus. Braking inputs required a fine touch and became more of a thought process than a muscular action, Chris noted. He added that the additional power was very reassuring but a bit abrupt for this application. While many drivers could easily adapt, this pad may be better suited to a heavier vehicle or higher-speed applications, he explained.
“Without being completely calibrated to the pedal feel, it’s easy to slow down too much at the end of the slalom and into the final turn with the HP Plus,” John said. “However, simply think the word ‘brake’ and the car slows. You can work the pedal with your toes and ankle, not the big muscles of your leg, allowing you to really fine-tune the brake pedal pressure.
The DTC-60 is one of Hawk’s many race-specific compounds, products that have no business being used on a street-driven car. For one, these pads are only meant to work between 400 and 1600 degrees Fahrenheit. Until the pads reach that temperature range, they’re tough on rotors and create copious amounts of noise and dust. They’re simply designed to cope with the rigors of track use.
Despite its hardcore nature, the DTC-60 worked surprisingly well on the test course. “As a true race pad, I expected a big upward swing in initial bite and stopping power as the pad warmed up,” Chris explained. “This was not the case, as the pad responded strongly to the initial pedal application and had stopping power to spare, even when cold.”
Two negative traits did crop up, however. The initial bite was strong enough to momentarily lock the front tires until weight transfer took place. This somewhat delayed full braking, as the ABS computer struggled to keep up with the instantaneous brake force. The pad’s peak braking g-loads suffered, and the drivers could feel the ABS system cycling pressure on and off.
The DTC-60 brake pad also lacked feel and feedback through the pedal. “The friendly handshake of the HPS pad had turned into an iron fist,” Chris noted. “The pedal has a somewhat dead feel,” John added. “I find it difficult to read what is going on in the tires’ contact patch. Successive laps created some familiarity with the DTC-60 as I learned how to gently squeeze the pedal rather than jab at it.”
The funny thing about brakes is that the less you use them, the faster you can lap an autocross course. The secret to a quick run is knowing exactly when and how much to brake, then avoiding the pedal entirely the rest of the time.
While our drivers noticed obvious differences in the feel of the brake pads, the data showed otherwise. There were no significant objective differences between any of the brake pads in terms of the lap times, peak stopping forces, or stopping distances. This makes sense, as we didn’t change the biggest factor in braking performance: the tires.
However, good pedal feel and consistency can definitely help driver comfort—which can then translate to confidence and better performance. Our recommendation is to shop for autocross pads based on feel rather than concept. And if you want to crib from our notes, our drivers loved both the HPS and HP Plus pads—we’ll be running the HPS in the future.
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I'm no racer, but one of our more consistent local winners uses the cheapest organic pads he can find for his Camaro in the cones. When he hauls it to a stop at the end, you can see puffs of orange flames coming off the clouds of dust from the pads. His rationale is that the short runs don't get them hot enough to be an issue, and (since he drives it on the street) the organic pads don't shred the rotors. Any glazing he gets during the few runs he does are easily scrubbed away on the trip home and he's left with normal street braking again.
That's just an anecdote from one racer, but that was his story and he's sticking to it.
I use craptastical ordinary pads I the Datsun I road race. Note I have Z car brakes on a 1600lb car so heat isn't an issue. I'm also not giving up and performance to people using high end race pads. When I raced a showroom stock Miata I tried both the Hawk Pads and the stock Mazda pads and found the same thing the test did, the Hawk pads had better feel but the more aggressive pad also went through rotors faster. I went to the stock pads for this reason. Basically I don't think there is a wrong answer here.
Oh hi, Per Schroeder.
Very interesting. I have tried quite a few pads on the FiST and found much of the same to be true. Track pads worked great on the track, but for autocross they were lightswitches with no modulation at all. Some national-level folks actually prefer the OEM pads from Ford, but even at that, there are two different part #s available based on year and one is better than the other.
My WAG is grippier pads would only be a benefit with equally grippy tires. Otherwise, you are just trying to not lock up or engage the ABS as much?
And I'm also surprised to see a post by Per?
I'm with Curtis on this one, although the camaro with race brakes that runs locally does look cool in pictures with the glowing rotors on course.
Per? Are you ...back? Like for real?
I prefer R4S versus R4E for autocrossing, but once you get to higher speeds and longer runs when temperatures can be reached and held, my preference shifts to R4E.
Mezzanine said:Per? Are you ...back? Like for real?
Holy crap I didn't even catch that.
Mezzanine said:Per? Are you ...back? Like for real?
The article is from the February 2011 issue, they posted it under his name since he wrote it.
So no, he's not back, but he has been known to lurk here.
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