Li Auto ONE Big Brake Kit Upgrade / TTSPORT Classic 8703S
Li Auto ONE is a heavy SUV — curb weight lands around 2,300 kg — and owners kept reporting the same complaint: hard stops were fine, but the first part of the pedal travel felt soft and vague, which on a two-ton crossover reads as "the brakes aren't really biting." This case walks through a front six-piston / rear four-piston TTSPORT upgrade built to fix that initial bite and firm up the whole pedal.
The build: front TT8703S six-piston calipers with 405x34mm high-carbon heat-treated rotors, and rear TT6411 four-piston calipers with 380x28mm rotors, a TT electronic parking brake (EPB) caliper, and TT stainless steel lines — all fitted behind the car's stock 21-inch wheels.
Vehicle & Kit Specs
| Item | Specification |
|---|---|
| Vehicle | Li Auto ONE, large SUV, ~2,300 kg curb weight, 21-inch stock wheels |
| Front caliper | TTSPORT TT8703S monobloc six-piston caliper, three opposed pairs of equal-size pistons, 54.96 cm² total piston area |
| Front rotor | 405 x 34mm high-carbon heat-treated rotor, drilled |
| Rear caliper | TTSPORT TT6411 monobloc four-piston caliper (32/28mm pistons, 28.38 cm² total piston area, ~2.2 kg each), symmetric lightweight design, paired with a TT electronic parking brake (EPB) caliper |
| Rear rotor | 380 x 28mm high-carbon heat-treated rotor |
| Bracket | Vehicle-specific caliper brackets machined to match the Li Auto ONE's OEM knuckle geometry |
| Lines | TT stainless steel brake lines |
Why It Works
The front TT8703S is a monobloc casting — machined from one piece rather than bolted halves — which cuts the flex that lets a caliper's clamping force get "absorbed" instead of transmitted to the pads. Three opposed pairs of equal-diameter pistons push pad pressure evenly across the pad face, and a combined piston area of 54.96 cm² gives the system real clamping authority versus the stock setup.
- Bigger, heavier rotors (405x34mm front, 380x28mm rear) hold more heat and resist fade better than the smaller stock discs, and the drilled surface helps clear dust and gas from the pad face.
- The rear TT6411's monobloc build keeps each caliper down to about 2.2 kg despite the added EPB hardware, so unsprung mass stays low and doesn't work against handling.
- Vehicle-specific brackets are machined to the Li Auto ONE's own knuckle data, so the kit locates correctly under the factory 21-inch wheel — no spacers, no guesswork.
- Stainless lines resist the ballooning that rubber lines can suffer under hard, repeated braking, which helps keep pedal feel consistent stop after stop.
Set side-by-side, the difference from stock is easy to see: the factory rotor is smaller with less friction surface and a plain face, while the TTSPORT high-carbon heat-treated rotor runs cooler under repeated hard stops and its drilled pattern doubles as both a visual upgrade and a way to keep the pad face cleaner.
Installation Gallery
What brake kit is used on this Li Auto ONE upgrade?
Does the kit fit behind the Li Auto ONE's stock wheels?
How much does the rear TT6411 caliper weigh?
Need fitment confirmation? Choose the closest TTSPORT series or send your vehicle, wheel size, and intended use before ordering.