Color coordination is key in building a true performance car. Scratch that. Forget I said anything (even though I really meant it). That the color of Brembo's calipers match Project Miata's inimitable hue is purely an auspicious coincidence. I didn't choose to utilize the 313mm two-piece floating rotors and Brembo's renowned red four-piston Gran Turismo calipers because they'd look good nestled behind the 17-inch RO_JAs. Oh, no. The real reason these brakes were chosen is because they are huge, offering, among other things, impeccable heat dissipation, an issue that surprisingly plagues the lightweight roadster.
Taking a gander at the factory brakes reveals why the Miata can be manufactured at such little cost. The brake design, like many imports, is, for the lack of a better word, simplistic. The front rotors are vented and measure 10 inches in diameter and the calipers are a sliding, single-piston design. At best, these stoppers are adequate for average street driving, but once you push the car to its limits you'll quickly learn the limitations of such a setup.
Even though the stock brakes have only single pistons, sliding calipers seem like they would still push the brake pads onto the rotors with equal force across the face of the pad. They don't. The problem is the leading edge of the pad tends to bite hard into the spinning rotor, digging that end in and pulling the trailing edge out. The result is not only uneven pad wear, but also less brake pad contact patch on the rotor, which leads to longer braking distances, excessive pad heat, and premature pad wear. The solution to this problem is to run a multiple-piston caliper offering sequentially sized pistons.
The Gran Turismo package utilizes Brembo's aluminum (i.e., lightweight) GT2 caliper, which houses four pistons: two inboard and two outboard. The two pistons on the leading edge of the caliper are 36mm in diameter, while the trailing edge pistons measure a stouter 40mm. The sequential piston design allows more force to be placed at the rear of the brake pad, which subsequently presses the brake pad against the rotor evenly, offering even pad wear and a greater contact patch.
Brembo's Gran Turismo kit also includes 313x28mm, two-piece, cross-drilled, vented, floating rotors. What makes the Brembo rotor so great is the entire unit is built to handle and dissipate the intense heat that is generated during harsh driving. One of the ways this is accomplished is through the use of a cast-iron rotor bolted to a billet aluminum hat with fasteners that utilize springs on every other bolt. If you run your fingers over the bolts, every other bolt connecting the hat to the rotor should mildly move. These are known as McLaren clips. This design preloads the assembly and offers the benefits of a floating design while eliminating annoying disc noise.
Once the brakes were installed on Project Miata, a simple process that took roughly an hour and a half, the brakes were bled. The process of bleeding brakes is a simple one, but if done wrong it could mean the end of your life. The GT2 caliper only has one bleed screw, which is located at the top of the caliper, whereas some of Brembo's larger calipers utilize inboard and outboard bleed screws. Once the brakes are bled per Brembo's directions, Brembo recommends completing a second bleeding. The second bleeding should take place after the car has been driven at least a mile or two. Driving the car will usually knock any trapped air bubbles to the top of the caliper, meaning if you don't bleed the brakes a second time, you will be driving with air in the line, and that, my friends, is a bad thing.
The next step is to bed the pads and discs. This is done by braking gingerly for three-second durations, and repeating roughly 30 times. If you get into the car and brake hard the first time, you may actually mate the brake pad and disc together, essentially ruining your new brakes. Another important thing to remember is that Brembo rotors are cadmium coated to eliminate corrosion while the rotors are being stored. When you're bedding the brakes, you're also scraping off the protective coating, so it is important to bed the brakes and heat-cycle them per Brembo's instructions.
A concern many people have with big brakes, especially on lightweight cars, is that the weight of the brakes will add unnecessary unsprung weight and cause more harm than good. To see what evils were being bolted to the front spindles, I decided to measure the stock single-piston caliper and 10-inch rotor and compare it to the weight of the Brembo Gran Turismo package. The stock caliper weighed a scant 8 pounds, while the factory rotor tipped the scales at 10 pounds. The Brembo four-piston caliper, with its efficient aluminum construction and billet aluminum caliper bracket, weighed 8.2 pounds, which, added to the 12.3-pound caliper, meant the Brembo setup weighed only 2.5 pounds more per side than the factory setup. That's not the end of the world.
For this kinda dough, the Brembo Gran Turismo kit better work. To see if I'd just dropped nearly 2,400 clams for no good reason, I tested the car both before and after the Brembos were installed. Initial driving impressions, however, told the most important portion of the story. Under harsh driving it was possible to overheat the stock brakes to the point where smoke would pour from the fenders, but now the car stops again and again like a stuttering fool. There is literally no brake fade. Also, threshold braking is made easier by the incredibly linear feel of the brake pedal. The stock brakes would grab and then seemingly loosen up; the Brembos grab and squeeze the rotors steadily, offering a confident stop.
Since everyone's a slave to the spreadsheet, I tracked the braking distances of the car both stock and modified. With the pathetic factory setup, the car could pull from 60mph to a complete stop within 136 feet. The difficulty with obtaining a "best" stopping distance was that the stock sliding calipers and the continuous heat sinking into the brakes make stopping characteristics more and more unpredictable, where the 136-foot distance was accomplished through varying degrees of uncontrolled tire lock and frantic pedal pushing. Threshhold braking was all but impossible to accomplish with any consistency, and when the brakes really weren't cooperating, the 60-0 distance was as high as 170 feet. With the Brembo setup, however, the brakes never overheated so the pedal always felt the same, making consistent stopping distances easy to accomplish. The shortest distance the car managed with the Brembos was an impressive 121 feet, and I was able to produce that number time after time. If your Miata is equipped with ABS, this number will probably be significantly shorter.
For the next installment of Project Miata, I'm going to touch on one of the things that most people tackle first: horsepower. All I need to do now is attempt to pull enough grunt from the little 1.8L motor to justify the addition of such incredibly strong brakes.
The Low Down
Pros: With massive 313x28mm rotors and four-piston calipers, heat dissipation and clamping power is no longer an issue. The same Gran Turismo package is available for nearly all compacts.Cons: You need to run 17-inch wheels to fit the brakes as puny 16s won't cut it.
Install Difficulty: Intermediate
Verdict: No fade and impeccable brake control. Life doesn't get any better, that is, unless you can find us a copy of Zapped! on DVD.