They’re Here: GrimmSpeed 4-Piston Brake Caliper Kits for Subaru Applications
Confident Stops. Clear Purpose. The GrimmSpeed Brake Kit Has Landed.
You asked for real braking performance and we delivered.
GrimmSpeed’s all-new 4-Piston Brake Caliper Kit is now available for multiple Subaru platforms. Purpose-built from the ground up, this system was designed to solve the shortcomings of the stock floating caliper setup found on the WRX, STI, and BRZ/GR86 platforms. It’s not a retrofit. It’s not a repackaged OEM unit. It’s ours — engineered, tested, and manufactured with the same focus and precision that define everything we do.
This kit brings serious bite, balanced pressure, reduced fade, and OEM-like fitment without the need for donor STI parts or unreliable secondhand components. If you’ve been waiting for a brake solution designed by Subaru people — for Subaru people — this is it.
We didn’t just make a caliper. We rethought the entire system. The fixed 4-piston design applies dual pistons to each side of the rotor, creating symmetric clamping force that improves control and reduces pad taper. The caliper body is forged from 6061-T6 aluminum, offering both strength and lightness, then hard anodized for corrosion resistance and long-term durability. The pistons themselves are vented, Type 3 hard anodized, and machined from 6061-T6 billet for superior heat dissipation. Each kit includes brackets made from billet 4140 chromoly steel, electrocoated for additional protection and stiffness. Even the smallest details, like ED-plated bolts, stainless guide pins, and bleeder valves, were chosen for performance under pressure.
Real-world performance? We’ve got the data. Third-party testing showed lower brake drag, better pad wear, smoother pedal response, and more consistent pad pressure distribution than OEM 2-Piston and OEM STI Brembo calipers. These aren’t just stats, they’re what you feel every time you hit the brakes.
Fitments and Compatibility
GrimmSpeed Big Brake Caliper Kits are available for the following Subaru platforms:
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2015–2021 WRX / STI (VA Chassis)
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2022+ WRX (VB Chassis)
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2013+ BRZ / Toyota GR86 / Scion FR-S (1st & 2nd Gen)
Proper leading caliper configuration -
2008-2014 WRX / STI (GR/GD) Chassis
Each kit is matched to specific rotor sizes and uses widely available pad types:
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Rotor Sizes: 315mm, 326mm, and 340mm (based on application)
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Pad Options: Readily Available FMSI D1001 (F50) and FMSI D968 (F40), depending on the platform
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No brake lines included — the kits work with stock lines, though upgraded lines may be recommended
*Note: BRZ/GR86 kits are internally mirrored due to their leading caliper configuration.
The two views below from the top, and side feature a transparent red overlay comparing our GrimmSpeed 4-piston caliper to the STi 4-piston caliper.
Dimensional Analysis
The back view reveals key dimensional differences that impact performance. Our GrimmSpeed caliper is precisely 3.5 mm wider on the outboard side. This slight increase provides improved braking force distribution while maintaining a profile similar enough to the STi caliper to ensure excellent wheel fitment compatibility.
Height Considerations
From the side perspective, our engineering team incorporated an 11.5 mm height increase at the caliper spring bridge securing point. Our extensive testing confirms this rarely affects wheel clearance except in extreme cases with particularly small wheel diameters. We've successfully verified compatibility with select 17-inch wheels using appropriate offset specifications. For customers concerned about fitment with their specific setup, we've created printable templates that can be used to verify clearance before installation.
Retrofit Ready
Even if you own an older model WRX or STI, or a model we haven’t listed, it doesn’t mean these Calipers can’t work for you. Our 4-Piston Brake Caliper Kits can be retrofitted to a vast array of Subaru models/trims. The key is confirming that you have the proper rotor size and pad type to match the caliper. We have put together a comprehensive chart of the rotors and pads needed for each specific application. (See below) Once you have all the right components in place, our GrimmSpeed caliper kits will bring modern braking performance to your Subaru.
What’s in the Box
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(2) GrimmSpeed 4-Piston Calipers
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(2) Vehicle-specific brackets
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Complete hardware pack (banjo bolts, crush washers, bridge bolts, bleeder caps, cotter pins, guide pins, and more)
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Printable 1:1 scale fitment template for wheel clearance
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Available in Red or Gunmetal Gray anodized finishes
This kit isn’t a flex. It’s a solution. For daily drivers, weekend enthusiasts, time attack competitors, and anyone who simply wants more confidence when they hit the brakes. The GrimmSpeed Big Brake Caliper Kit is the answer to the braking limitations of the stock Subaru setup.
