The Porsche 718 (Cayman/Boxster) is widely regarded as the best-handling sports car in its class. Its mid-engine balance is sublime. However, for owners who push the car on track, the standard 4-piston calipers (even on the GTS) are the primary bottleneck. They lack the thermal capacity and pad volume of the 911 GT3, leading to fade and rapid wear. This owner solved that problem with an "OEM+ GT Upgrade": fitting 911 GT3 6-piston calipers and StopFlex Carbon-Ceramic rotors.
The Struggle
While the 718 chassis is brilliant, the braking system on non-GT4 models has limitations:
- Thermal Capacity: The smaller 330mm/350mm iron rotors on the S/GTS models heat soak quickly during extended track sessions, leading to a soft pedal.
- Pad Volume: The standard 4-piston calipers use smaller pads that wear rapidly under track duress, requiring frequent and expensive replacements.
- Brake Dust: The factory pads generate excessive dust, which is a pain to clean from the intricate 20-inch wheels.
Technical Specification
This build is the ultimate "OEM+" solution. It retrofits the massive 6-piston front calipers from the 991 GT3/Turbo onto the 718 chassis, paired with advanced StopFlex Carbon-Ceramic rotors.
| Vehicle | Porsche 718 Cayman/Boxster (982) |
|---|---|
| Front Hardware | OEM 991 GT3 6-Piston Caliper + 410mm CCB |
| Rear Hardware | Factory 4-Piston Caliper + 390mm CCB |
| Weight Saving | ≈ 20 kg (44 lbs) Total Reduction |
| Pad Material | StopFlex Track & Street Ceramic Compound |
Compatibility Redline
This is a Custom Big Brake Kit (BBK) application. It requires upgrading the front uprights/knuckles or using specific adapters to mount the 991 GT3 6-piston calipers. The StopFlex rotors are engineered to pair specifically with this upgraded caliper setup. This is also a direct replacement for standard 718 4-piston calipers.
Engineering Validation
1. GT3-Level Stopping Power
By upgrading to the 6-piston GT3 caliper, pad surface area increases by nearly 50%. Combined with the massive 410mm (16.1 in) StopFlex rotor, thermal capacity is effectively doubled. This setup eliminates fade entirely, allowing you to brake deeper and harder, lap after lap, just like a GT4 RS.
2. Mid-Engine Agility Amplified
The 718 is all about balance. Removing ~20 kg of rotating unsprung mass from the corners sharpens the steering response and allows the suspension to react faster to mid-corner bumps. The car feels lighter on its feet, enhancing the telepathic connection the 718 is famous for.
3. OEM+ Aesthetics
This upgrade looks like it came from the factory. The massive yellow calipers fill the 20-inch wheels perfectly, giving the car a "baby GT4" appearance. The carbon-ceramic rotors add a high-tech, exotic flair that distinguishes the car from a standard 718.
4. Zero Dust, Low Maintenance
The virtually no-dust formulation of our ceramic pads keeps your wheels pristine, even after a spirited drive. Additionally, the carbon-ceramic rotors are designed to last the lifetime of the vehicle for most street/track hobbyist drivers, offsetting the initial cost with long-term savings.
Installation Gallery
In-Depth Porsche 718 FAQ
Q: Why retrofit 911 GT3 calipers onto a 718?
The standard 718 4-piston calipers are great for the street but limit pad options and thermal capacity on track. The 6-piston GT3 caliper uses a much larger pad shape (D1774/D1666) available in many racing compounds, and its larger body is stiffer, providing better pedal feel and modulation.
Q: Is this system overkill for a street car?
From a pure stopping distance perspective, perhaps. But for driving enjoyment, absolutely not. The reduction in unsprung weight improves ride quality and steering feel every day. Plus, the elimination of brake dust is a massive quality-of-life improvement for any Porsche owner.
Q: Will this fit under my factory 20-inch wheels?
Yes. This 410mm/390mm setup is designed to clear standard Porsche 20-inch wheels (Carrera S, Turbo, etc.). However, 19-inch wheels will likely not clear the 410mm front rotor and 6-piston caliper.
Q: Do I need to change the master cylinder?
Generally, no. The 718 master cylinder moves enough fluid to operate the 6-piston front calipers effectively. The pedal feel remains firm and linear, similar to a GT4.
Q: What is the lifespan of these rotors?
For a 718 that sees mixed street and track use, StopFlex rotors are incredibly durable. They resist the oxidation that kills carbon-ceramic rotors on older Porsches (Gen 1/2 PCCB). You can expect over 200,000 km of life on the street.
