Why owners bring in an SU7 Ultra
The SU7 Ultra is over two tons before you add a driver, and most of the time it stops itself with regen. That's the trade-off of one-pedal driving: the friction brakes barely get used on a normal commute, then get asked to do the whole job the moment regen tapers off — a hard stop from a high closing speed, a long downhill grade, a track session, or the car simply running out of regen capacity when the battery's cold or near full.
That's the pattern we see with heavy EVs generally, and it's a real engineering tension on the SU7 Ultra specifically: a car with genuine track pace and a curb weight that makes every one of its friction stops count double. Owners who come to us for this conversion are usually chasing the same thing — a rotor that behaves the same on stop twenty as it did on stop one, on a car whose factory ceramic setup is already good but gets pushed harder than most.
What wasn't working
- Confidence dropping on the third or fourth hard stop of a downhill run
- Uncertainty about how the factory rotor behaves once regen contribution drops off
- Wanting a rotor built for repeated heat cycling, not just occasional hard use
- Concern about rotor condition after long stretches of light, regen-only driving
What owners want instead
- A pedal and bite point that stays consistent from the first stop to the tenth
- A rotor built with the factory calipers still in place, no electronics to rework
- A clean rotor face that isn't corroding while regen does the daily work
- Confidence that the friction brakes can take over completely without drama
The build: what's on this car
| Vehicle | Xiaomi SU7 Ultra |
|---|---|
| Front setup | Factory 6-piston caliper with 430mm STOPFLEX long-fiber carbon ceramic rotor |
| Rear setup | Factory caliper with 410mm STOPFLEX long-fiber carbon ceramic rotor |
| Rotor construction | 3D continuous long-fiber carbon ceramic matrix |
| Pads | STOPFLEX endurance pad configuration matched to the ceramic rotor surface |
| Upgrade scope | Direct-fit front and rear rotor replacement, factory caliper layout retained |
Confirm before you order
This build is specific to the Xiaomi SU7 Ultra, not the wider SU7 lineup. The Ultra runs its own brake hardware, so confirm your car matches this exact 430mm front and 410mm rear setup before you order.
What long-fiber carbon ceramic brakes change when regen runs out
A heavy EV asks something unusual of its friction brakes: almost nothing, most of the time, then everything at once. That's a harder cycle for a rotor than steady daily use, because the material goes from cold and idle straight to a hard, hot stop with no warm-up in between.
| STOPFLEX feature | Why it matters on the SU7 Ultra | What you notice |
|---|---|---|
| Continuous long-fiber construction | Long fiber carries load across the whole rotor body instead of relying on short, chopped strands, which matters when a 2-ton-plus car dumps heat into the rotor in one sudden stop rather than a gradual buildup. | A rotor built for the shock of a first hard stop, not just gradual heat cycling. |
| High-temperature friction stability | Once regen backs off on a downhill run or a hard track stop, rotor temperature climbs fast and stays there through the next stop. | Tested rotor surface friction still holds around 0.3μ at 900°C, so bite doesn't fall off a cliff on the third or fourth stop. |
| Roughly half the weight of steel | The Ultra is already carrying serious mass; cutting rotating weight at each corner works against that, not with it. | Lighter unsprung mass and a slightly sharper reaction from the suspension over broken pavement. |
| Rust-free rotor surface | Regen-heavy driving can leave the friction brakes doing little real work for days at a stretch. | No orange flash-rust ring behind the wheel after the car sits, rains on, or coasts on regen for a week. |
| CCB-specific pad compound | A pad built for iron doesn't transfer onto a ceramic surface the same way once things get hot. | A low-metallic compound stable to about 750°C, with average friction around 0.44, matched specifically to this rotor face. |
Here's the detail most people skip: cold bite. An untuned ceramic rotor bites less than iron on a cold morning — that's physics, not a flaw — and it's a real issue on an EV, because regen itself is often reduced when the battery is cold, stacking a weaker regen contribution on top of weaker cold friction right when you need both. STOPFLEX tunes the pad compound and ceramic coating specifically for that cold-start window, so the gap closes without pretending it disappears entirely.
What gets better
- More repeatable pedal feel through back-to-back hard stops
- Rotor material better suited to sudden, unwarmed hard braking
- Lower unsprung mass working with, not against, a heavy platform
- A clean rotor face during long stretches of light regen-only driving
What to confirm first
- Your car is the Ultra trim, not another SU7 variant
- Front and rear calipers match this 430mm/410mm factory layout
- Whether you want a street pad or a harder track-leaning compound
- How much of your driving is genuinely regen versus hard braking
One honest trade-off: if you almost never brake hard and let regen do nearly all the work, the biggest gains here — heat stability and repeatable bite — won't come up much. The rust resistance and dust reduction still apply either way, but you're paying for headroom you may rarely use. Rotor service life and long-term value are covered in more detail in our carbon ceramic brake cost guide, and the material difference versus a factory steel rotor is broken down on our carbon ceramic versus cast iron brakes comparison. An SU7 Ultra owner who pushed a similar build is covered in our SU7 Ultra racing-spec carbon ceramic brake case study.
If you're not sure your car matches the spec shown here, send us your details and we'll confirm Xiaomi SU7 Ultra fitment before you order through our carbon ceramic brake disc kit collection.
Fitment and installation
This is a rotor-only swap, not a caliper conversion, so the factory 6-piston front and factory rear calipers stay exactly where they are. The rotor is built to the same hat offset as the factory disc, which is what keeps the caliper's piston travel and pad contact centered without shimming anything or touching the brake-by-wire calibration.
The first thing we ask for before quoting isn't a photo of the wheel — it's confirmation of trim and axle scope, because the Ultra's brake package doesn't carry over to other SU7 variants. Nine times out of ten, a fitment question on this car comes down to trim confirmation, not a measurement problem.
On the bench, the caliper comes off, the factory rotor comes off the hub, the STOPFLEX rotor goes on at the matched offset, and the caliper goes back on and gets torqued to spec. Pads get bedded in gradually — a handful of moderate stops working up to firmer ones — before the car sees its first genuinely hard braking event.
- Confirm SU7 Ultra trim and current mileage on the factory ceramic rotors
- Confirm front and rear caliper type matches this 430mm/410mm setup
- Tell us your regen habits versus hard-braking frequency
- Tell us if the car sees track days, mountain descents, or mostly commuting
Bedding matters more here than on a gentler car, because the first real heat cycle the new rotor sees might be a genuinely hard one if you drive mostly on regen. Ease into it with moderate stops first. And on the first cold morning after a fresh install, give the pedal a beat longer than usual before you lean on it hard — cold ceramic needs that first stop to wake up.
What changes on the road
We don't have an instrumented before-and-after for this build, and you should be skeptical of anyone who publishes exact stopping-distance numbers without a test sheet to back them up. What we can describe honestly is the pattern this kind of build is designed to produce.
| Situation | Factory setup | After the STOPFLEX upgrade |
|---|---|---|
| Repeated hard stops on a downhill grade | Bite and pedal feel can drift as heat builds through the run | Built to hold a more consistent bite point stop after stop |
| First hard stop after days of regen-only driving | Rotor goes from cold and idle straight into a hard load | Long-fiber matrix designed for that sudden jump in demand |
| Cold morning, first stop of the day | Ceramic bites softer than iron until it warms slightly | Pad and coating tuned for cold starts, narrowing the gap |
| Wheel cleanliness after a week of driving | Some dust buildup depending on pad wear | Very low dust with the matched STOPFLEX pad compound |
| Rotor condition after extended light or regen-heavy use | Standard ceramic resists rust already | Same rust resistance, plus refurbishable rotors if wear adds up |
No lap times, no measured stopping distances — just what this combination is built to hold onto through repeated hard braking. If your driving is almost entirely gentle and regen-based, expect the dust and rust benefits to show up daily, and the heat-stability benefit to show up on the rare day you actually need it.
Build gallery
SU7 Ultra brake questions
The SU7 Ultra already comes with ceramic brakes. Why replace them?
This isn't about fixing a weak factory system. STOPFLEX uses long-fiber carbon ceramic construction, chosen for stronger structural integrity and better resistance to heat-related wear than chopped-fiber rotor designs, which matters most on a heavy EV that leans on its friction brakes hard once regen backs off.
Will my rotors rust if I mostly drive on one-pedal regen?
A carbon ceramic rotor doesn't flash-rust the way an iron disc does after sitting unused between hard stops. That matters on an EV where the friction brakes can go days without real work, then get asked for everything at once.
Does this keep the factory calipers and brake electronics?
Yes. This is a direct-fit rotor replacement that keeps the factory front and rear calipers and the original mounting geometry, so it works with the car's existing brake-by-wire and regen blending. Confirm fitment for your exact car before ordering.
Will this shorten my stopping distance?
In a single hard stop, tire grip sets the limit, not the rotor. The real gain is consistency: a more heat-stable rotor holds a more repeatable pedal and braking point across back-to-back hard stops, which is exactly the load pattern once regen runs out.
Can STOPFLEX carbon ceramic rotors be refurbished?
Yes. STOPFLEX long-fiber carbon ceramic rotors can be refurbished, which matters if you drive the car hard and want a longer-term rotor strategy instead of buying a full replacement set.
Is this worth it if I mostly drive gently and rely on regen?
You'll still get low dust and a rotor face that resists rust between uses, but the strongest case for this upgrade is repeated hard braking, like a downhill run, a loaded highway stop, or a track day where regen alone can't do the job.
