Brembo GT-S Hard Anodized Rear Big Brake Kit for Porsche 996 / 997.1 C2 (380mm) | 9004AS Series

This Brembo GT-S Rear Big Brake Kit (9004AS series) is a rear axle upgrade for Porsche 996 and 997.1 C2 models, replacing the factory braking system with a fixed 4-piston Brembo caliper and 380mm x 28mm two-piece rotor setup. It increases rear braking stability and heat capacity, particularly on cars where the factory rear system struggles to keep pace with upgraded front brakes or more aggressive driving.

Rear brake performance becomes more noticeable on 996 and 997 builds once front braking capacity is increased. The factory rear setup can fall behind, leading to imbalance, uneven wear, or reduced stability under heavy braking. This kit brings the rear system back into balance by increasing rotor mass and improving caliper rigidity, helping maintain consistent rear braking contribution during repeated stops.

Brembo’s GT-S line uses hard anodized calipers for improved surface durability and heat resistance, paired with the same core design principles found in their OEM and motorsport systems. This kit includes GT 4-piston cast monobloc radial mount calipers loaded with Brembo FM1000 pads for street and performance use. It’s paired with high carbon two-piece rotors—available in Cross Drilled, TY1, or TY3 configurations depending on the selected variant—with corrosion-resistant plating, along with Goodrich braided lines and CNC billet radial mounting hardware.

Add it up—4-piston rear calipers, 380mm rotors, braided lines, and proper mounting hardware. This is the step that keeps rear braking consistent when the rest of the system has already been upgraded.

---

Technical Details

• Manufacturer: Brembo
• Series: GT-S
• Part Series: 9004AS
• Position: Rear axle
• Application Range: Porsche 996 and 997.1 C2
• Calipers: Brembo 4-piston cast monobloc radial mount (hard anodized finish)
• Rotor Size: 380mm x 28mm
• Rotor Type: Two-piece high carbon with corrosion-resistant coating
• Rotor Variants: Cross Drilled, TY1, TY3
• Pads: Brembo FM1000 (street/performance)
• Brake Lines: Goodrich braided lines
• Hardware: CNC billet radial mounting hardware included
• Disc Air Gap: 16mm
• Disc Annulus: 54mm

---

Fitment & Compatibility

Fits Porsche 996 and 997.1 Carrera 2 models. This kit replaces the factory rear braking system with a Brembo caliper and larger rotor package.

IMPORTANT: Before you purchase a Brembo Performance or Racing Brake system you should always confirm that the vehicle's wheels have adequate clearance, regardless of wheel size.

Fitment instructions can be found here
Caliper measurements can be found here

These CAD drawings represent the clearance of an Original Equipment (left) brake system compared to a GT system with inadequate clearance (middle), and one with proper clearance (right).