The Xiaomi SU7 has rapidly gained a reputation for its potent electric powertrain and sharp handling. However, for enthusiasts who truly push the car, the factory 4-piston braking system can feel like the weak link. Under high-speed emergency braking or spirited driving, the stock setup may struggle to manage the vehicle's weight and speed, leading to brake fade and a lack of confidence.
To solve this mismatch between acceleration and deceleration, this owner chose a "one-and-done" solution: upgrading to the top-tier AP Racing 8521 6-piston calipers paired with STOPFLEX Carbon-Ceramic Rotors.
The Front-Axle Performance Build
This build replaces the factory front brakes with motorsport-grade hardware designed to fit within the 20-inch wheels. It focuses on maximizing thermal capacity and pedal feel.
- Vehicle: Xiaomi SU7
- Front Calipers: AP Racing 8521 (Radi-CAL II) 6-Piston Calipers
- Front Rotors: STOPFLEX 400mm (15.7 in) Carbon-Ceramic Discs
- Brake Pads: STOPFLEX Performance Ceramic Pads
- Hardware: Custom mounting brackets and bolts
Important: System Compatibility
This case study features a custom Big Brake Kit (BBK) using aftermarket AP Racing fixed calipers. Our STOPFLEX carbon-ceramic rotors are engineered to pair with this specific high-performance hardware.
Please note: These rotors are custom-configured for the BBK and are not a direct replacement for the factory Xiaomi SU7 calipers. If you wish to retain your factory calipers, please contact us for OE-fitment options.
Why This Combo Transforms the SU7
- Motorsport-Grade Control: The AP Racing Radi-CAL caliper is renowned for its stiffness and lightweight design. When paired with our 400mm (15.7 in) carbon-ceramic rotor, it provides immediate bite and consistent modulation that far exceeds the factory 4-piston setup.
- Fade-Proof Endurance: The thermal capacity of STOPFLEX carbon-ceramic rotors ensures that the brakes remain effective even after repeated high-speed stops. This is a critical safety upgrade for a heavy, fast EV.
- Optimized Efficiency: By reducing unsprung weight, the system improves the SU7's handling agility and suspension response. Additionally, the virtually no-dust pads keep the wheels clean, and the corrosion-proof rotors ensure the system is always ready to perform, regardless of weather.
Installation Gallery
Frequently Asked Questions for SU7 Owners
Q: Why choose AP Racing calipers over the factory ones?
A: The factory 4-piston calipers are adequate for daily driving but lack the thermal mass and rigidity for high-performance use. The AP Racing 6-piston Radi-CAL caliper provides significantly more clamping force, better heat dissipation, and a firmer pedal feel, making it the ideal match for our carbon-ceramic rotors.
Q: Does this upgrade affect regenerative braking?
A: No. The system works seamlessly alongside the car's regenerative braking. In fact, because our rotors are corrosion-proof, they don't suffer from the surface rust issues common on EVs that use friction brakes less frequently. This ensures smooth, vibration-free braking when you do need to use the pedal.
Q: Is this setup harsh for street driving?
A: Not at all. While it uses track-grade technology, our pad compound is formulated for refined street operation. It offers excellent cold bite and smooth modulation without the noise or harshness often associated with racing brakes.
