The BYD Song L-EV is impressive. With its CTB (Cell-to-Body) chassis and double-wishbone suspension, it has legitimate cornering potential. But it has one massive enemy: Weight. This particular owner had already upgraded to Alcon RC6 calipers with steel rotors ("Stage 1"). It solved the braking power issue, but it didn't solve the physics issue. To truly unlock the suspension, we needed to cut rotational mass. That's why we moved to "Stage 2": retaining the Alcon calipers but swapping the heavy steel for StopFlex Carbon-Ceramic rotors.
Stage 1 was Good, Stage 2 is Perfect
Here is the reality of modifying heavy electric SUVs: Big calipers alone aren't enough.
The owner's initial setup (Alcon RC6 + Steel Rotors) provided excellent clamping force. However, during aggressive driving, two problems remained:
- Thermal Saturation: A 2.3-ton EV generates massive kinetic energy ($E_k$) under braking. Steel rotors soak up this heat and eventually fade.
- Unsprung Weight: A 400mm steel rotor is an anchor. It forces the suspension to work harder, making the car feel heavy and "crashy" over bumps.
The solution wasn't to change the caliper—the RC6 is excellent. The solution was to change the metallurgy of the disc.
The Build Specification
This is a targeted "Rotor Swap" upgrade. We kept the existing high-performance calipers and optimized the friction ring.
| Vehicle | BYD Song L-EV |
|---|---|
| Front Caliper | Alcon RC6 (6-Piston) - Retained |
| Rotor Upgrade | StopFlex 400mm LCCB (Carbon Ceramic) |
| Pad Material | StopFlex CCB-Specific Compound |
| Wheel Size | 20-inch (Required) |
⚠️ Fitment Redline
This setup uses a 400mm rotor. You cannot run this on 19-inch wheels. 20-inch wheels are the minimum requirement to clear the caliper and rotor assembly. If you are running the factory 20-inch wheels, spacers may be required depending on the offset.
The Engineering Data
Why spend the money to switch from steel to carbon? The numbers justify the investment.
1. Rotational Mass Reduction
We weighed the components during the swap. The difference is night and day for the suspension geometry.
| Component (400mm) | Steel Rotor | StopFlex CCB | Savings |
|---|---|---|---|
| Rotor Ring (Per Side) | ~14.5 kg | ~7.5 kg | -48% |
| Total Axle Weight | ~29 kg | ~15 kg | ~14 kg Saved |
2. Thermal Capacity
The Song L is heavy. Repeated stops from highway speeds can push steel rotors past 600°C, where they soften and fade. StopFlex CCB rotors remain stable well past 1,000°C. You get consistent friction, stop after stop, without the "mushy pedal" feeling.
Installation Gallery
BYD Song L Upgrade FAQ
Q: Can I use Alcon RC6 calipers with carbon rotors?
Yes. The Alcon RC6 is a very versatile caliper. We supply a StopFlex rotor hat that offsets the disc perfectly to match the Alcon mounting points. You simply need to swap the pads to our CCB-compatible compound.
Q: Does this affect the electronic brake booster (Bosch iBooster)?
No. The Song L uses an intelligent brake system. Upgrading the mechanical hardware (rotors/calipers) does not interfere with the ABS or ESP logic. In fact, the consistent friction of carbon ceramics often makes the ABS engagement smoother.
Q: Is it suitable for daily driving?
100%. This is arguably better for daily driving than high-performance steel brakes because it eliminates brake dust. Your wheels stay clean, and the system is silent thanks to our specific street-compound pads.
