Girodisc Rear Brake Rotors – Porsche 991
The Girodisc A2-238 Rear Rotor Set (380x30mm) is a direct replacement for the OE cup car discs used on the Porsche 991 GT3 Cup. Engineered for performance and reliability under extreme track conditions, these rotors bolt directly to your car and work seamlessly with the original calipers and ABS system—no modifications required.
Race-Proven Two-Piece Design
Each Girodisc rotor is designed and manufactured in the USA with precision components to ensure durability and superior thermal management. The central hat section is CNC-machined from U.S.-sourced 6061-T6 aircraft-grade aluminum, while the outer ring is made from Girodisc’s proprietary cast iron alloy, poured and machined entirely in-house. The curved vane design actively pumps cooling air through the disc, reducing temperatures during intense braking to prevent fade and warping.
Features
• Direct replacement for OEM Porsche 991 GT3 Cup rear discs (380x30mm)
• Two-piece floating rotor design for optimal heat management
• 6061-T6 aluminum hats machined from U.S.-sourced billet
• Proprietary cast iron rotor rings with curved vane cooling geometry
• 12 high-strength alloy steel drive pins with cadmium plating
• Anti-noise spring washers eliminate rattle while maintaining full float
• Class 12.9 hardware and hardened washers for secure mounting
• Significantly reduces unsprung and rotational mass
• Reusable hats—replace only rings when worn
• Sold/priced per pair
• Optional center-lock drive pin kit available
Vehicle Fitment
• Porsche 991 GT3 Cup (All model years) – Rear
• Fits OEM calipers and ABS
• Center-lock wheel option available upon request
Girodisc A2-238 Rear Rotors – Porsche 991 GT3 Cup FAQs
Do these rotors fit directly without modifications? Yes. The Girodisc A2-238 system is a direct bolt-on replacement for OEM rear discs on the 991 GT3 Cup.
What is the advantage of a two-piece floating rotor? The floating design allows the iron rotor ring to expand under heat without stressing the aluminum hat, improving performance, reducing weight, and preventing cracking or distortion.
Can I reuse the aluminum hats? Yes. Once the cast iron rings wear out, you can replace just the rings and retain the existing hats and hardware.
Do these rotors make noise? No. The use of anti-noise spring washers ensures quiet operation even when cold, while maintaining true floating capability under heat.
Are these rotors sold individually? No. The Girodisc A2-238 rotors are sold as a pair for the rear axle.
Is a center-lock version available? Yes. Girodisc offers a specific drive pin option for vehicles equipped with OEM center-lock hubs—select this option when ordering.
Enhance your Porsche 991 GT3 Cup’s braking performance with the Girodisc A2-238 2-Piece Rear Brake Rotors (380x30mm)—precision-engineered, race-proven, and built to handle the most demanding conditions on track.
