GrimmSpeed 4-Piston Brake Caliper Kit - 08-21 STI, 15-21 WRX (340mm Rotor)

Description

The stock single-piston caliper found on most Subaru platforms gets the job done — but it wasn’t designed for the kind of aggressive driving, tracking, or build evolution most GrimmSpeed drivers pursue. That’s where our 4-Piston Brake Caliper Kit comes in.

Purpose-built for Subaru performance, this fixed caliper setup brings balanced stopping power, improved heat management, and consistent pedal feel to your favorite chassis. Designed in-house and tested under real-world conditions, the system offers a true performance solution — with no need to chase down used Brembos or deal with custom brackets.

Each kit is application-specific, pairing our forged aluminum calipers with the correct rotor and bracket configuration for your setup. Calipers are available in your choice of Red or Gunmetal Gray anodized finishes, both designed to withstand heat and resist corrosion while delivering a clean, motorsports-ready look. From street builds to track cars, this is the braking confidence your Subaru deserves.

Key Features

• Forged 6061-T6 Aluminum Caliper Body – 2-piece design, hard anodized for strength and corrosion resistance

• Dual Piston Setup – 44mm primary and 41mm secondary pistons provide even pad pressure and reduced taper

• Heat-Managed Pistons – Type 3 hard anodized and vented for superior thermal performance

• Lightweight Design – Approximately 9.9 lbs per corner with bracket and hardware

• Pad Compatibility – FMSI D1001 or D968 (varies by application)

• Rotor Compatibility – Works with commonly available Subaru OEM and STI rotors

• No Brake Lines Required – Compatible with factory lines (new lines may be recommended depending on vehicle)

What’s Included

• (2) GrimmSpeed 4-Piston Brake Calipers (choose Red or Gunmetal)

• (2) Vehicle-Specific Billet 4140 Steel Caliper Brackets

• Full Hardware Kit:

  • Bridge bolts

  • Banjo bolts

  • Crush washers

  • Bleeder dust caps

  • Caliper guide pins

  • Security cotter pins

  • Caliper spring bridges + bolts

• Printable 1:1 Fitment Template

• Install Instructions

Fitment

15-21 WRX with 340mm rotors and matching pads

04-21 STI with 340mm rotors and matching pads

• Rotor Size: 340mm

• Pad Type: F40 (FMSI D968)

• Designed for use with OEM-style hubs and rotors — no knuckle swaps or custom adapters required.
  

* OEM Subaru 340mm Rotor (5x114.3 Cars Only) Part No.-26300VA000