BMW 5 Series (G38) Big Brake Kit Upgrade / TTSPORT Classic 8703s

BMW's G38 (the long-wheelbase 5 Series built for the Chinese market) delivers plenty of power and a chassis tuned for real driving involvement. But on this particular car, the factory brakes were the weak link — the pedal lacked confidence exactly where a sporty sedan needs it most, at the limit of a hard stop. The fix was a full front-and-rear TTSPORT big brake kit, with an EPB-compatible rear caliper so the factory parking brake still works.

Acceleration and handling get most of the attention on a performance sedan, but braking is what lets a driver commit to the throttle and the corner in the first place. Stopping power, pedal feel, and fade resistance under repeated hard stops all matter as much as horsepower — which is why this G38 got a matched front six-piston / rear four-piston TTSPORT setup instead of a pad-and-fluid refresh.

Vehicle & Kit Specs

Why It Works

The TT8703s front caliper uses a one-piece (monobloc) cast body instead of a bolted two-piece design, which cuts down on flex under hard braking — less caliper deflection means more of the pedal's input goes directly into clamping force instead of getting absorbed by a caliper that's bending. Racing-grade stainless pistons and a six-piston layout also spread clamping force over a larger pad area, which helps even pad wear and heat transfer.

• Larger 380x34mm front / 365x29mm rear rotors add mass and surface area over stock discs, giving the system more heat capacity before fade sets in on repeated stops.
• Drilled rotor faces on both axles help vent gas and heat build-up at the pad/rotor interface during hard, repeated braking.
• The kit was fitted to run behind the car's stock 19-inch wheels, so there's no wheel swap or spacer required to make the bigger hardware fit.
• The rear TT8903 caliper keeps the G38's electronic parking brake working, so the upgrade doesn't cost the driver any factory convenience feature.

Installation Gallery