# Girodisc Rear Brake Discs 279x20 for Ferrari 246 Dino (1969–1974) – 308 GTB and GTS

> Pair of Girodisc rear discs, 279 × 20 mm, part no.: A2-021. High-performance floating brake discs on aluminum hubs for the Ferrari 246 Dino (1969–1974) and the Ferrari 308 GTB and GTS (1976–1985).

- URL: https://www.gt2i.ch/en/brake-disk-for-bell/224486-girodisc-rear-brake-discs-279x20-for-ferrari-246-dino-19691974-308-gtb-and-gts-3666618858111.html
- Reference: GIRO-A2-021
- Price: CHF 1,515.61
- Brand: GIRODISC
- Availability: out of stock

## Description

The Girodisc A2-021 rear brake discs, measuring 279 × 20 mm, improve heat management during repeated braking on the Ferrari 246 Dino (1969–1974) and the Ferrari 308 GTB and GTS (1976–1985). Their cast-iron rotors and aluminum hubs form a floating assembly designed to manage thermal stresses and facilitate the replacement of rotors under wear. Sold in pairs, with one left-hand rotor and one right-hand rotor.
These discs 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 observed.
The curved internal cooling fins channel air through the disc to dissipate heat during repeated braking. The floating mounting limits stresses caused by differences in thermal expansion between the pad and the housing and helps the pad center itself between the brake pads, maintaining consistent contact when hot.
The hub is made of 6061-T6 aluminum. 
New brake pads must be installed with new rotors or brake discs. Their shape and compound must match the mounting, casting, and intended use; follow the specific requirements for this part number and perform the prescribed break-in procedure.
Specifications for Girodisc A2-021 discs for compatible vehicles
Brand: Girodisc
PartNumber: A2-021
Position: rear
Sizes (diameter × thickness): 279 × 20 mm
Vehicles and models: Ferrari 246 Dino (1969–1974); Ferrari 308 GTB and GTS (1976–1985)
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 assembly
Catalog part number: D2-021. Verify compatibility with the caliper generation before replacement.
Internal ventilation: directional curved fins
Minimum thickness: 18 mm
Overall height: 73 mm
Manufacturing of main components: United States
Vehicles compatible with Girodisc part number A2-021
Ferrari 246 Dino (1969–1974)
Ferrari 308 GTB and GTS (1976–1985)
Ferrari 246 Dino (1969–1974): For 5-mounting hubs only.
Ferrari 308 GTB and GTS (1976–1985): Big brake kit including front brake calipers, front and rear brake discs, brake pads, and hoses.
Each application is subject to its specific brake configuration, calipers, and any requirements for brake pads or spacers. Please verify these requirements before ordering.
Girodisc A2-021 Mounting Requirements
Ferrari 246 Dino (1969–1974): For 5-mounting hubs only.
Ferrari 308 GTB and GTS (1976–1985): Big brake kit including front brake calipers, front and rear disks, brake pads, and flexible hoses.
Brake Pads and Brake System for Compatible Vehicles
Choose brake pads whose shape is compatible with the calipers, the A2-021 track, and/or the A2-021 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 that is compatible with the original hydraulic system.
Maintenance of the Girodisc mounting on compatible vehicles
Replacing the pads alone helps keep the controlled rotors in good condition. Reusing a rotor 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 A2-021 for compatible vehicles
What are the sizes of the A2-021 discs for my vehicle? The part number shown measures 279 × 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 mounting hubs.
Do I need to replace the brake pads on my vehicle?Yes. Always install new brake pads with new rotors or new braking surfaces. Their shape and compound must be compatible with the A2-021 track and/or rotor and with 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 A2-021 Bowl Brake Discs
279 × 20 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 masses compared to a comparable one-piece cast-iron disc.

## Features

- Product type: Brake disc on a Bol
- Diameter in mm: 279
- Position: Rear
- Thickness: 20