Girodisc 380x32 Rear Brake Discs for Porsche 911 (991) GT3 and GT3 RS (2013–2019) without CCB

The Girodisc A2-146 rear brake discs, measuring 380 × 32 mm, improve thermal management during repeated braking on the Porsche 911 (991) GT3 and GT3 RS (2013–2019). Their cast-iron rotors and aluminum hubs form a floating assembly designed to manage thermal stresses and facilitate rotor replacement due to wear. Sold as a pair, including one left-side and one right-side rotor.

These rotors are intended for the rear axle of compatible vehicles in the configuration shown below. They retain the compatible caliper mounting; any required spacers and brake pad specifications must be followed.

The curved internal cooling fins channel air through the rotor to dissipate heat during repeated braking. The floating mounting minimizes stresses caused by thermal expansion differences between the rotor and the housing and helps the rotor center itself between the brake pads, maintaining consistent contact under heat.

The hub is made of 6061-T6 aluminum. The high-strength steel drive pins are cadmium-trimmed to resist corrosion. Spring washers minimize cold-mounting noise while allowing the necessary compression for the floating mount.

New brake pads must be installed with new discs or rotors. Their shape and compound must be compatible with the mounting, casting, and intended use; follow the specific requirements for this part number and perform the prescribed break-in procedure.

Specifications for Girodisc A2-146 discs for compatible vehicles

• Brand: Girodisc
• PartNumber: A2-146
• Position: rear
• Sizes (diameter × thickness): 380 × 32 mm
• Vehicles and models: Porsche 911 (991) GT3 and GT3 RS (2013–2019)
• Braking surface: high-resistance cast steel
• Packaging: Pair of complete rotors, one left and one right with disc bells.
• Housing: 6061-T6 aluminum
• Construction: two-piece floating mounting design
• Catalog part number: D2-146. Verify compatibility with the caliper generation before replacement.
• Internal ventilation: directional curved fins
• Number of internal fins: 72
• Minimum thickness: 30 mm
• Original rotor diameter: 380 mm
• Weight / weight reduction: Weight per complete disc: approximately 10.48 kg (23.1 lb).
• Manufacturing of main components: United States

Vehicles compatible with Girodisc part number A2-146

• Porsche 911 (991) GT3 and GT3 RS (2013–2019)

• Porsche 911 (991) GT3 and GT3 RS (2013–2019): Without PCCB.

Each application is subject to its specific brake system configuration, calipers, and any requirements for brake pads or spacers. Please verify these conditions before ordering.

Girodisc A2-146 Mounting Requirements

• Porsche 911 (991) GT3 and GT3 RS (2013–2019): Without PCCB.

Brake Pads and Brake System for Compatible Vehicles

Choose brake pads whose shape is compatible with the calipers, track, and/or the A2-146 rotor, and whose compound is suitable for sport driving or track use. The Endless, pagid Racing, or Ferodo Racing ranges may be considered after verifying the appropriate part number.

For intensive use, we recommend compatible aviation-grade hoses and high-performance brake fluid that meets the vehicle’s specifications, along with proper bleeding and fluid replacement. This recommendation complements a mounting compatible with the original hydraulic system.

Maintenance of the Girodisc mounting on compatible vehicles

Replacing the pads alone helps keep the rotors in good condition. Reusing a rotor for up to three pad replacements is subject to inspection of its condition, its mounting hardware, and the mounting instructions; this number does not constitute a guaranteed service life. Use new mounting hardware with each pad replacement.

FAQ — Girodisc A2-146 for Compatible Vehicles

What are the sizes of the A2-146 discs for my vehicle? The part number shown measures 380 × 32 mm and is mounted on the rear axle. The diameter alone is not sufficient: also check the brake system type and mounting requirements.

Is the product sold in pairs? Yes. It includes a left and a right disc for the same axle. Both discs are shipped with their hubs.

Do I need to replace the brake pads on my vehicle?Yes. Always install new brake pads with new rotors or new brake pads. Their shape and compound must be compatible with the A2-146 rotor and/or braking surfaces and the calipers. Then break in the rotors and pads according to the prescribed procedures.

How do I identify the left and right sides? Girodisc rotors come with a label attached to each rotor: LEFT for the left side and RIGHT for the right side, as viewed in the direction of travel. On a left-hand-drive vehicle, “LEFT” corresponds to the driver’s side and “RIGHT” to the passenger side. Follow these labels and the instructions. On models with curved internal fins, the rolling direction depends on this internal ventilation; the surface grooves alone are not sufficient to determine the side.

How do I break in this mounting on my vehicle? Follow the Girodisc procedure and the brake pad manufacturer’s instructions to build up an even transfer ply. The PDF documents below detail installation and break-in.

PDF Documents for Mounting and Break-in

We have included two PDF documents below: an instruction manual for installing and breaking in the discs, and an instruction manual for installing new tracks on existing bowls. Consult the document that applies to your specific task before you begin.

Key Features of Girodisc A2-146 Bowl Brake Discs

• 380 × 32 mm size for rear braking on compatible vehicles.
• 6061-T6 aluminum rotor and floating mount to manage thermal stresses.
• Internal ventilation via curved fins to dissipate heat.
• Replaceable pads to maintain a two-piece mounting.
• Left/right pair identified for mounting.
• Aluminum rotors help reduce unsprung and rotating mass compared to a comparable one-piece cast iron disc.