4-Piston Rear Caliper Pair for Porsche 992 GT3 – 9GT615423 / 9GT615424

Name: 4-Piston Rear Caliper Pair for Porsche 992 GT3 – 9GT615423 / 9GT615424
Brand: ForzaCCB.com
SKU: 8240826450059
Price: 2100.00 USD
Availability: InStock

Only 2 left

Price per pair

$2 100

~~$3 400~~ Sale $2 100

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Upgrade your rear axle with genuine Porsche GT3 rear 4-piston calipers, a compact and high-performance OEM solution used across multiple Porsche platforms and widely favored for custom carbon ceramic brake conversions.

These calipers are based on the latest Porsche GT brake architecture and are well suited both for direct OEM replacement on GT cars and for rear big brake retrofit projects on larger luxury and SUV platforms.

Key Features

Genuine Porsche OEM rear brake calipers.
4-piston fixed monobloc design for stable pedal feel and consistent rear braking performance.
Compact outer profile, ideal for applications where wheel barrel clearance matters.
Excellent choice for custom rear carbon ceramic brake kits.
Factory-finished calipers, perfect for premium street, performance, and retrofit builds.

OEM Part Numbers

9GT615423 – rear left caliper.
9GT615424 – rear right caliper.
Known superseding / variant references include 9GT615423A, 9GT615424A, 9GT615423Q, 9GT615424Q.

Porsche Applications

These rear calipers are associated with multiple Porsche GT and performance platforms, including:

Porsche 911 992 GT3 / GT3 RS / S/T.
Porsche 718 982 Cayman GT4 / GT4 RS.
Porsche 718 Spyder / Spyder RS.
Porsche Cayenne applications are also referenced in parts listings using the same caliper family.
Additional listings also reference compatibility across Macan and Panamera parts catalogs.

Ideal for Retrofit Builds

Because this caliper combines strong clamping force with a relatively compact body, it is an excellent rear axle solution for custom brake conversions on heavier vehicles.

It is especially suitable for bespoke rear brake kits for:

Porsche street and track builds
Rolls-Royce retrofit projects
Bentley brake conversions
Mercedes-AMG G63 / G-Class applications
Other heavy luxury SUV and sedan platforms requiring a compact high-performance rear caliper

What’s Included

1 x rear left caliper
1 x rear right caliper
Factory-installed hardware as shown

Notes

For Porsche applications, please confirm exact fitment by VIN before ordering.
For Rolls-Royce, Bentley, G63 AMG, and other non-Porsche vehicles, these calipers are intended for custom conversion use only and require vehicle-specific brackets, rotor sizing, lines, and engineering.
Sold as a matched pair unless otherwise specified.

CCB Rotor & Wheel Fitment Guide

Minimum wheel diameter guidance by rotor size. Always validate final fitment using a physical template and measured clearances.

Rotor Size (Diameter x Thickness)	Minimum Wheel Size	Technical Fitment Notes
310mm × 22mm	16-inch	Fits most 16-inch wheels. Installation on 15-inch wheels is possible only with specific low-profile callipers and is not generally recommended.
330mm × 28mm	17-inch	Standard entry-level size for performance brake upgrades. Fits comfortably within most 17-inch alloy wheels.
345mm - 356mm × 32mm	18-inch	Common mid-range size. Requires 18-inch wheels with standard barrel clearance.
380mm × 32/34mm	19-inch	The industry standard for Carbon Ceramic (CCB) and heavy-duty steel systems. Fits most 19-inch wheels; verify spoke clearance for wider callipers.
390mm × 36mm	19-inch (Tight Fit)	Fits 19-inch wheels with high-clearance barrels (flat inner bed). 20-inch wheels are recommended to ensure adequate air gap for cooling.
400mm - 405mm × 36/38mm	20-inch	Requires 20-inch wheels. Ensure the wheel barrel does not taper significantly near the mounting face.
410mm - 420mm × 38/40mm	21-inch	Standard fitment for 21-inch wheels. Can fit select 20-inch motorsport wheels with specialised flat barrel profiles (template verification required).
440mm × 40/42mm	21-inch (Minimum)	Extreme fitment. 21-inch is the absolute minimum requirement. 22-inch wheels are strongly advised for safe operating clearance and heat dissipation.

Essential Clearance Requirements

To ensure safety and prevent damage to components, please observe the following industry-standard tolerances when measuring your wheels:

Radial Clearance (Barrel): A minimum gap of 3mm is required between the top of the calliper and the inner wheel barrel to account for heat expansion and wheel deflection under load.
Axial Clearance (Spokes): Ensure a minimum of 3mm clearance between the face of the calliper and the rear of the wheel spokes.
Balance Weights: Ensure wheel balancing weights are positioned so they do not foul the brake calliper. We recommend placing weights outboard of the calliper zone for tighter fitments.

Important Fitment Disclaimer

The wheel sizes listed above represent minimum technical requirements based on standard barrel profiles. Due to significant variation in alloy wheel designs, particularly spoke curvature (X-factor) and inner barrel contours, meeting nominal diameter alone does not guarantee compatibility.

We strongly recommend verifying clearance instrumentally using printable fitment templates rather than relying only on visual estimates or stated wheel specifications. Please ensure at least 3mm clearance in all directions to account for thermal expansion and dynamic wheel deflection.