Girodisc 326x20 Rear Brake Discs for Subaru WRX STI (2018+)

The Girodisc A2-185 rear brake discs, measuring 326 × 20 mm, enhance braking endurance during sustained use on Subaru WRX STI models (2018+). Their cast-iron rotors and aluminum hubs form a floating assembly designed to manage thermal stress and facilitate rotor replacement due to wear. Sold as a pair, including one left-hand and one right-hand 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 cast iron track and floating connection allow the disc to accommodate differences in thermal expansion between its two parts and center itself between the brake pads. This construction also makes it easier to replace the tracks when they are worn.

The hub is made of 6061-T6 aluminum.

New brake pads must be installed with new discs or new raceways. Their shape and compound must match the mounting configuration, the cast iron, and the intended use; comply with the specific requirements for this part number and perform the prescribed break-in procedure.

Specifications for Girodisc A2-185 discs for compatible vehicles

• Brand: Girodisc
• PartNumber: A2-185
• Position: rear
• Sizes (diameter × thickness): 326 × 20 mm
• Vehicles and models: Subaru WRX STI (2018+)
• Braking surface material: high-resistance cast steel
• Packaging: Pair of complete rotors, one left and one right with disc bells.
• Hub: 6061-T6 aluminum
• Construction: two-piece floating mounting design
• Catalog part number: D2-185. Verify compatibility with the caliper generation before replacement.
• Manufacturing of main components: United States

Vehicles compatible with Girodisc part number A2-185

• Subaru WRX STI (2018+)

• Subaru WRX STI (2018+): Rear pad brackets must be adapted.
• Subaru WRX STI (2018+): The metal brake pads on the original equipment and certain aftermarket brake pads require adjustment to clear the brake disc mounting while retaining the parking brake. It is essential to follow the instructions and use pre-prepared brake pads when available.

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

Girodisc A2-185 Mounting Requirements

• Subaru WRX STI (2018+): Rear pad brackets must be modified.
• Subaru WRX STI (2018+): The metal brackets on the original equipment and certain aftermarket pads require adjustment to clear the rotor mounting while retaining the parking brake. It is essential to follow the instructions and use pre-machined pads when available.

Brake Pads and Braking System for Compatible Vehicles

Choose brake pads whose shape is compatible with the calipers, track, and/or A2-185 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 flexible 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 calipers in good condition. Reusing a caliper for up to three pad replacements is subject to inspection of its condition, its mounting components, and the mounting instructions; this number does not constitute a guaranteed service life. Use a new mounting component each time you replace the pads.

FAQ — Girodisc A2-185 for compatible vehicles

What are the sizes of the A2-185 discs for my vehicle? The part number shown measures 326 × 20 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 come with their disc bells.

Do I need to replace the brake pads on my vehicle?Yes. Always install new brake pads with new brake discs or new braking surfaces. Use a compound suitable for cast iron and your specific use. The metal brackets on the original brake pads and on some aftermarket pads require adjustment to clear the brake disc mounting while maintaining the parking brake. It is essential to follow the instructions and use pre-prepared pads when available.

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 from 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 A2-185 Bowl Brake Discs

• 326 × 20 mm size for rear braking on compatible vehicles.
• 6061-T6 aluminum rotor and floating mount to manage thermal stresses.
• Replaceable pads to maintain a two-piece mounting.
• Left/right pair identified for mounting.
• Aluminum rotors help reduce unsprung and rotating masses compared to a comparable one-piece cast-iron disc.