Part IX: Bigger Brakes, Longer Stops.
In the flurry of parts we've received since Project Miata's resurrection, it's been tough deciding what to work on next. And since the project was taken over by ex-USCC competitor Matt Andrews, it has taken on a new persona. We can barely keep up with how fast it's being built.
We planned to address engine tuning in this installment of Project Miata, but we're going after the brakes instead. With 187-wheel hp, R-compound tires and long weekends of continuous track pounding, the current brake setup is just not up to the job-more power would just hurt lap times at this point.
The heat load from serious track time makes quick work of the current brakes, which are so small they can only be described as "cute." While larger than the brakes found on earlier 1.6-liter cars, the rotors on the Project Miata are a measly 10 inches in diameter; perfect for filling the 14-inch wheels it originally came with and stopping the stock, sub 100-wheel hp car. Neither of these conditions apply now.
Project Miata now wears wider 16x7-inch Buddy Club P-1 Racing SF wheels for the street and forged 15x7.5-inch SSR Competition track wheels, both of which put a lot more rubber to the ground than stock. The added traction and slight increase in wheel diameter gives us the option to look into a brake package with larger discs and serious calipers to increase brake torque and dissipate heat more quickly.
Most existing kits on the market for the Miata use thin rotors and Wilwood's Dynalite caliper, which is intended primarily for street use and is too flexible for our application. Calipers made from softer materials flex more as braking pressure is applied, which has a significant impact on braking torque and pedal feel. Also, the Dynalite calipers don't come in the piston diameters we need to maintain a neutrally balanced brake bias using the stock rear calipers.
So we enlisted Brakezone, one of Wilwood's largest dealers in non-domestic markets, to develop a setup that was up to the masochistic treatment we have in mind for project Miata. They worked with Wilwood to piece together a front brake kit using Wilwood's Dynapro four-piston calipers and two-piece rotors. We used a Dynapro caliper with optional stainless-steel pistons for its better thermal properties and corrosion resistance.
The rotor is available drilled and slotted or just slotted with directional vanes for heavy-duty applications. We used the latter. An 11.75 x .810-inch rotor was as large as was allowable while still clearing the 15-inch SSR wheels. The fit was so snug that we had to remove the wheel weights from behind the spokes of our track wheels and move them to the rim in order to provide enough clearance. Brakezone custom engineered the aluminum rotor hats, caliper mounting brackets, and stainless steel braided brake lines and fittings that allow the new assembly to sit far enough inboard on the hub to accommodate as many 15-inch wheel variations as possible.
Even with significantly larger brake components, overall weight dropped from 18 to 16.5 pounds per front corner, including pads and lines. Brakezone now offers this complete front kit on their website (www.brakezone.com) for $1250-pretty cheap for race caliber brake components.