BMW 4 Series Big Brake Kit Upgrade / TTSPORT Classic 8705

BMW's 4 Series pairs a turbocharged engine with a genuinely fun chassis, but the factory brakes can start to feel soft after enough hard use — rough roads, hot laps, or just years of heat cycling the stock hardware. This 4 Series owner, who spends a lot of time on demanding mountain and touring roads, swapped in a TTSPORT TT8705 big six-piston caliper kit paired with 380x34mm high-carbon heat-treated rotors to get the pedal back.

The build ran on the car's stock 19-inch wheels, with the TT8705 caliper and 380mm rotor tucking in cleanly — no spacers, no wheel swap needed.

TT8705 is a monobloc, six-piston design built for the kind of larger, harder-working vehicles that need serious stopping power on tap — a meaningful step up from the factory brakes on this car.

Vehicle & Kit Specs

Why It Works

• A monobloc six-piston caliper flexes less under hard braking than a stock floating caliper, which means more consistent pad clamping and a firmer, more predictable pedal.
• The larger 380x34mm rotor adds mass and swept area, giving the system more thermal capacity to resist fade on long descents or repeated hard stops.
• The kit was designed to clear the car's stock 19-inch wheels, so the owner gets the bigger brake without changing wheel fitment or running spacers.
• Stainless steel lines replace the factory rubber hoses, cutting down on line expansion under pressure for a more direct pedal feel.

Installation Gallery

FAQ