6-Piston Brake Caliper for Audi e-tron GT RS – 4J3615123C / 4J3615124C – 410x38mm – Retrofit for Porsche Cayman & 21Z-Style Builds

Name: 6-Piston Brake Caliper for Audi e-tron GT RS – 4J3615123C / 4J3615124C – 410x38mm – Retrofit for Porsche Cayman & 21Z-Style Builds
Brand: ForzaCCB.com
SKU: 8299852628107
Price: 1600.0 USD
Availability: InStock

Price per pair

$1 600

~~$2 900~~ Sale $1 600

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Customs duties included in shipping.

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1 7–10 days Assembled and packed — rotors are in stock, aluminum hats are machined for your car.

2 Shipped — choose your transit

Express Courier Fastest UK, US, Canada — Fast Track Customs Clearance. 5–7 days

Air Freight Standard Door to door worldwide, fully tracked. 10–14 days

Sea Freight Economy Best rate on multi-kit and oversized orders. 30–35 days

Manufacturer WarrantyMinimum 6-month coverage
Aftersales Service Available after every purchase
Brake fitment guarantee We confirm caliper, rotor and hat fitment using your VIN, vehicle model, year and photos of your current brake setup.

View Audi customer cases 35 documented builds — real installs and brake setups

Only 2 left

Upgrade your braking system with a genuine OEM front caliper set from the Audi e-tron GT RS. These calipers are original Audi/VW Group parts with part numbers 4J3615123C and 4J3615124C, built for the front axle and paired with 410x38 mm brake discs.

This is a premium OEM solution for customers who want factory-level Brembo quality, strong stopping power, and a serious visual upgrade.
The caliper architecture is very close to the style commonly used in 21Z-type front brake retrofit projects, which makes it a popular candidate for custom big brake conversions.

Important: this is not a direct bolt-on universal kit. For retrofit use, the setup must be matched with the correct adapter brackets, rotor diameter, rotor offset, brake pads, and wheel clearance.

These calipers are commonly adapted for:

Porsche 718 Cayman.
Porsche 718 Cayman T.
Porsche 718 Cayman S.
Porsche 718 Cayman GTS.
Porsche 718 Cayman GT4.
Porsche 718 Boxster / Spyder.
Porsche 981 Cayman / Boxster.
Porsche 987 II Cayman / Cayman S.
Porsche Taycan-family custom brake projects.
Other 21Z-style front brake conversion builds.

If your project already uses a 21Z-style front brake concept, these Audi e-tron GT RS Brembo calipers can be an excellent OEM-based alternative when the bracket and rotor package are engineered correctly.

Key Features

Genuine Audi / Volkswagen Group OEM parts.
OEM part numbers: 4J3615123C / 4J3615124C.
Original application: Audi e-tron GT RS Quattro front axle.
Disc size: 410x38 mm.
OEM “Audi carbid” finish.
Ideal for custom big brake retrofit projects.
Commonly used in 21Z-style conversion builds with brackets.

Retrofit Fitment

Original fitment

Audi e-tron GT RS Quattro, front axle.

Common retrofit applications

Porsche 718 Cayman.
Porsche 718 Cayman T.
Porsche 718 Cayman S.
Porsche 718 Cayman GTS.
Porsche 718 Cayman GT4.
Porsche 718 Boxster.
Porsche 718 Spyder.
Porsche 981 Cayman / Boxster.
Porsche 987 II Cayman / Cayman S.
Porsche Taycan-family custom projects.
Other custom 21Z-style front brake setups.

Fitment note

Brackets required.
Rotor offset must be matched.
Wheel clearance must be checked.
Not a universal direct-fit kit.

Specifications

Item	Details
Brand	Audi Genuine Parts / Brembo
Part numbers	4J3615123C / 4J3615124C
Position	Front axle
Caliper type	6-piston
Disc size	410x38 mm
Original vehicle	Audi e-tron GT RS Quattro
Application type	OEM replacement / custom retrofit
Finish	Audi carbid

Why Choose This Set

This set gives you genuine OEM performance with modern Audi engineering.
It is a strong choice for customers who want a high-end brake upgrade without going fully into aftermarket-only solutions.

For retrofit customers, the main advantage is the combination of:

OEM quality.
Large 6-piston front architecture.
Strong fitment potential for Porsche Cayman and similar builds.
Good visual presence behind large wheels.

Important Notes

Please contact us before ordering to confirm:

your vehicle model and year,
wheel size and spoke clearance,
target rotor size,
bracket solution,
pad shape and disc offset.

This product is sold for OEM replacement and custom retrofit use.
Final fitment must always be verified for the exact vehicle and brake package.

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
280mm - 300mm × 20/28mm	15-inch	The smallest workable upgrade size, and only with compact low-profile callipers. Requires at least 340mm of clear inner wheel barrel. Steel systems only - carbon ceramic is not produced in this diameter range.
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.