BMW 3 Series (G28) Big Brake Kit Upgrade / TTSPORT Classic 8703
The G28-generation BMW 3 Series leans harder into comfort than its predecessors, and the brake pedal shows it. This build swaps the factory single-piston floating calipers for a TTSPORT front six-piston / rear four-piston plus EPB setup — here's what went on and why it changes the way the car stops.
The G28 still carries BMW's engineering pedigree in its chassis, but the brake hardware was clearly tuned for comfort over feel. That gap between how the car handles and how it stops is exactly what this build addresses.
The Stock Brake Problem
The factory G28 comes with a single-piston floating caliper up front. In braking tests, results were consistently unimpressive: a soft, light pedal, 100-0 km/h stopping distances in the 39-40 meter range, and noticeable fade after repeated hard stops. For a car marketed on sport credentials, that's a weak link — and it's why a growing number of new-3-Series owners are upgrading their brakes.
A single-piston floating caliper only clamps from one side and relies on the caliper body sliding to apply even pressure — a setup that flexes under load and gives the pedal that vague, low-effort feel drivers noticed on this car before the swap.
Vehicle & Kit Specs
| Item | Specification |
|---|---|
| Vehicle | BMW 3 Series (G28), 18-inch wheel fitment |
| Front caliper | TTSPORT TT8703 monobloc six-piston caliper, one-piece cast body; three piston sizes at 15.9 cm², 12.6 cm², and 10.2 cm² |
| Front rotor | 355x32mm high-carbon heat-treated drilled rotor |
| Rear caliper | TT6411 four-piston caliper (service brake) + TTSPORT EPB caliper, single-piston motor unit (parking brake) |
| Rear rotor | 355x28mm high-carbon heat-treated drilled rotor |
| Lines | TTSPORT stainless steel braided brake lines |
Why It Works
- A one-piece cast, six-piston fixed caliper flexes less than a stock floating caliper under hard braking, which translates directly into a firmer, more consistent pedal.
- Stepping up to 355mm rotors front and rear adds swept area and thermal mass, which is why TTSPORT rates the TT8703 for 355-405mm discs on mid-size cars like the 3 Series, C-Class, and A4.
- The TT8703's piston sizing and rotor range are matched to 18-inch and larger wheels, which is why this kit clears the G28's factory 18-inch wheel setup.
- Splitting rear duties between a TT6411 four-piston caliper for service braking and a dedicated EPB caliper for parking brake lets the shop install the kit without modifying the factory electronic parking brake components.
Installation Gallery
FAQ
What wheel size does this TTSPORT kit fit on the G28?
Does the rear kit replace the factory electronic parking brake?
What problem does this kit solve on the stock G28?
Need fitment confirmation? Choose the closest TTSPORT series or send your vehicle, wheel size, and intended use before ordering.