Planning for future go-fast parts we also had to think about braking. You really can't go faster if you can't stop faster too. So we looked at one of the best brakes on the market, AP Racing (distributed in the United States by Stillen). While we improve stopping we're also putting in some longer race-bred wheel lug studs from ARP.
The FR-S' OE brakes seem to need help, especially on the track. We've heard the stock pads last only about 20 minutes under stressful conditions before giving up.
AP Racing/Stillen brake units offer a burly alternative. Caliper biting power is increased with more pistons; the fronts are six-piston and the rears are four-piston, replacing the OEM two-piston calipers in front and one-piston rears. The two-piece aftermarket rotors are also significantly larger (more biting surface, greater cooling capacity). The front AP Racing pieces are 14 inches across and 1.26 inches thick versus the 11.6-inch factory discs that are only .96-inch thick. In the back, 13-inch diameter, 1-inch-thick AP Racing rotors supplant stockers, 11.4 inches across and .7 inch thick. The center hats on the rotors are also made of aluminum to reduce weight. To finish off the kit Stillen includes brand-new stainless steel braided brake lines to adapt the car to the AP Racing calipers and minimize flex that the OEM silicone lines cause. These are more than adequate for a high horsepower car, and we shall never need anymore braking power on our FR-S.
4. Starting up front, with the car raised and wheels off, the original caliper is the target. Steel-braided fluid lines come with the Stillen big brake kit, so we began by removing the factory lines. Then, the caliper is unbolted from the knuckle. With the caliper off, the OE rotor can come off as well as the brake shield.
With the rotors off, we go ahead and replace the lug studs. This involves unbolting and removing the hubs, an easier proposition in front without having to undo a hub axle bolt. Ideally, the stock studs should be pressed out, and the longer ARP versions should be pressed in.
5. After we return each newly studded hub to its knuckle of origin, the front caliper brackets are installed to accommodate the bigger binders. The AP rotors are installed on the hubs next, and then the calipers. Stainless steel braided lines are routed and secured in place.
6. Factory rear one-piston caliper versus AP four-piston rear caliper. Two-piece 13-inch rotors versus 11.4-inch factory rear.
7. There are two key differences in working with the FR-S' rear stoppers. First, in order to remove the hubs (to install the extended lug studs) we had to remove the hub axle nut. Second, rather than remove it, we decided to cut off the outer edge of the rear rotor dust shield, which we did with a plasma cutter (a reciprocating saw could work as well).