Installing the Powerslot Plus brakes is a matter of taking off the stock calipers and roto
Pedal SquishWhat really bothered us in the first place and started us down the road of brake re-engineering is the soft and squishy feel of the stock brakes. Even though the tC uses the same front brakes as the Toyota Celica GT-S, it doesn't share the same great brake feel. We wanted brakes that responded quicker and were more fade resistant.
A sloppy brake feel can be caused by several factors including improper pad selection, boiling brake fluid, caliper deflection, bulging brake lines, firewall flex, and a bit of brake engineering voodoo that we haven't figured out. To diagnose what is causing the problems, however, you must understand the role hydraulics play in the braking system.
When you step on the brake pedal, hydraulic fluid is rammed through a brake master cylinder, which amplifies your foot pressure and forces fluid through brake lines to the calipers. Pressure from the hydraulic fluid forces the calipers to push pad-covered pistons against the rotors. Since the pads are already touching the rotors even when you're off the brakes, when you do step on the brakes, the pistons move very little and the fluid has nowhere to go. Since the pads barely move and the hydraulic fluid is basically uncompressible, pushing against the pistons builds pressure. Like a balloon under pressure, the softest parts begin expanding first. In most cases, it's the rubber portions of the brake lines, followed by the firewall, and then the brake caliper prying itself apart as the pads push against the rotor. It's this expansion that makes the brake pedal feel soft and unresponsive. The harder you step on the pedal, the more these components will expand or bend. Our solution: Stiffen the parts that are expanding and flexing.
We already know the stock calipers aren't the main reason for the slop, since the Celica, which uses the same caliper and rotor, doesn't have such a squishy pedal. Besides, there isn't much you can do to strengthen a floating brake caliper other than replace it with a fixed type caliper unit from an expensive big brake conversion kit. Putting an $1,800 set of front brakes on a $16,000 car doesn't make much sense to us, so we're left with changing out the brake lines and picking pads that feel the best.
Squish, as we so scientifically call it, causes extra pedal travel with no additional brake response. The two "flexible" parts in the squish equation we can do something about are the soft, stock rubber brake lines and weak firewall. (Firewall flex is an issue because the brake master cylinder and booster are mounted on it. Every time you step on the brakes, the firewall temporarily and ever so slightly bulges out into the engine bay.)
For now, we'll only replace the stock brake lines with Goodridge stainless-steel-braided lines we sourced from The Tire Rack, since we haven't gotten around to making a master cylinder stopper.