The build: parts and fitment
| Item | Factory front brake | STOPFLEX front upgrade |
|---|---|---|
| Vehicle | Xiaomi SU7 | Xiaomi SU7 |
| Front caliper | OEM front caliper | AP Racing World Radi-CAL II CP8521, 6-piston |
| Front rotor | OEM steel disc | STOPFLEX 400mm carbon ceramic rotor |
| Front pads | OEM pads | STOPFLEX low-dust ceramic compound |
| Rear hardware | OEM caliper | Factory rear caliper retained |
| Front axle weight | Heavier steel package | Approximately 14 kg lighter |
| Wheel fitment | Standard | Stated to fit inside 20-inch wheels |
| Axle scope | — | Front big brake kit |
Confirm before you order
This is a custom front big brake kit built around the AP Racing CP8521 caliper and a 400mm carbon ceramic rotor. The kit is stated to clear 20-inch wheels, but spoke design and barrel clearance differ wheel to wheel, so your exact wheels need to be checked first. Keeping the factory front calipers is a different fitment path.
What the upgrade actually changes
| STOPFLEX feature | Why it matters on the SU7 | What you notice |
|---|---|---|
| AP Racing CP8521 6-piston caliper | The SU7 is quick and heavy enough to load the front brakes hard once regen tapers off. A stiff fixed caliper resists flex under that load. | A firmer pedal that stays where you put it instead of going long under repeated stops. |
| 400mm carbon ceramic rotor | More swept area and far higher heat tolerance than the steel disc handle back-to-back hard stops without fading. | Braking that feels the same on the tenth stop down a grade as it did on the first. |
| Half the rotor weight of steel | This build states roughly 14 kg off the front axle, all of it unsprung and rotating mass. | Lighter steering, less head-toss over bumps, a car that turns in a touch quicker. |
| Carbon ceramic won't rust | EVs lean on regen, so iron rotors sit unused and surface-rust fast. Carbon ceramic doesn't. | No orange rotor ring through the spokes and no gritty first-stop feel after rain. |
| Low-dust STOPFLEX pads | Open SU7 wheel designs show every bit of brake dust. | Wheels that stay clean far longer between washes. |
| Normal cold bite to about -20°C | A street car has to stop on the first cold stop of the morning, not after a warm-up lap. | Predictable cold braking, so the kit behaves like a daily brake, not a race-only part. |
What gets better
- Firmer, more consistent pedal under repeated hard braking
- More heat headroom from the 400mm carbon ceramic rotor
- About 14 kg less unsprung weight up front
- No rotor rust after rain or low-use EV driving
- Much lower brake dust with STOPFLEX pads
- Normal cold-stop feel for real daily use
What to confirm first
- Your exact 20-inch wheels clear the CP8521 caliper and 400mm rotor
- This is a front-axle kit; the factory rear caliper stays
- You want the custom CP8521 path, not a factory-caliper fitment
- Street-oriented pad compound is specified for daily driving
If you're not sure your SU7 matches the spec shown here, send us your wheel details and we'll confirm Xiaomi SU7 fitment before you order through our Xiaomi CCB collection.
Build gallery
SU7 brake upgrade FAQ
Does this front CCB upgrade change regenerative braking on the Xiaomi SU7?
No. Regen stays part of the car's control strategy and the friction brakes handle conventional stopping. A bonus with carbon ceramic rotors is that they don't rust after rain or light EV use, so first-stop feel stays cleaner than it does with iron discs.
Can I daily drive the AP Racing CP8521 and STOPFLEX setup on my SU7?
Yes, with a street-oriented STOPFLEX pad compound. Cold-stop behavior stays normal, response is smooth, and brake dust drops well below what iron rotors and OEM pads leave on the wheels.
Do I need specific wheels for this Xiaomi SU7 front big brake kit?
This is a custom front big brake kit built around a 400mm rotor and the AP Racing CP8521 caliper. It's stated to fit inside 20-inch wheels, but spoke shape and barrel clearance vary by wheel, so confirm your exact wheels before ordering.
Can I keep the factory rear brakes on the Xiaomi SU7?
Yes. This configuration upgrades the front axle while the factory rear caliper is retained, so you get a major gain in front braking capacity without converting the whole car.
How much weight does the carbon ceramic front package save?
This build states an approximate 14 kg reduction on the front axle. STOPFLEX carbon ceramic rotors run about half the weight of same-size steel discs, which cuts unsprung and rotational mass and sharpens steering response.
