Which rotors take the Mercedes-Benz 390mm Front Replacement Rings?

The GiroDisc Mercedes-Benz 390mm Front Replacement Rings fit the hats of the A1-123 front rotor for the C63 AMG Black Series and the A1-190 front rotor for the C7 Audi RS6 and RS7. GiroDisc lists D1-123 as the replacement ring for both.

What thickness are the 390mm front rings when new?

GiroDisc lists the ring at 36mm new with a minimum of 34mm, figures taken from its A1-190 rotor page. The minimum is also marked on the hat and the ring edge. Replace the pair at that point or if a crack runs to the outer edge.

Will these rings fit an Audi or Mercedes on factory rotors?

No. They are designed only for GiroDisc hats. A car still on its factory discs has no hat to carry the ring, and factory two-piece hats or other brands use a different drive-pin arrangement, so the complete GiroDisc rotors must be fitted first.

Does an RS6 owner need anything else for a ring change?

No. Each pair comes with replacement mounting hardware, so the iron and the fasteners are renewed together. The aluminum hats are the only parts carried over from the existing A1-190 rotors, and the job is done on the bench with standard tools.

Why does one ring serve both a Mercedes and an Audi?

Both GiroDisc front rotors use a 390mm ring of the same thickness and vane design, so GiroDisc builds them around a common ring. That keeps the part in regular production and makes replacement rings easier to source for owners of either car.

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Description

GiroDisc Mercedes-Benz 390mm Front Replacement Rings for C63 AMG Black Series and C7 Audi RS6 and RS7

GiroDisc’s Mercedes-Benz 390mm Front Replacement Rings serve two different cars: the C63 AMG Black Series on GiroDisc A1-123 rotors and the C7 Audi RS6 and RS7 on GiroDisc A1-190 rotors. Each ring is 390mm across and 36mm thick with 72 curved vanes, cast from GiroDisc’s own iron and machined in Bellingham, Washington. For owners who already run the hats, these rings are the whole cost of a front brake refresh.

Fitment and Installation

The rings fit GiroDisc A1-123 and A1-190 front hats only, not factory two-piece hats or other brands. With the rotors on the bench, unbolt the worn rings, mount the new pair on the correct sides with the supplied hardware, and tighten the cap screws to no more than 60 in-lb.

Features

390mm outer diameter, 36mm new thickness
72 curved cooling vanes
Slotted friction face
Shared by GiroDisc front hats for the C63 AMG Black Series and C7 RS6 and RS7
Replacement mounting hardware included
High-carbon iron poured in the USA

What’s Included

Front replacement rings (L/R)
Replacement mounting hardware

Applications

Audi RS6: C7 | with GiroDisc A1-190 front rotors | 4.0L twin-turbo V8
Audi RS7: C7 | with GiroDisc A1-190 front rotors | 4.0L twin-turbo V8
Mercedes-Benz C63 AMG Black Series: with GiroDisc A1-123 front rotors | 6.2L V8

Notes

These rings fit the hats of the GiroDisc 390mm C63 Black Series front rotors and the GiroDisc C7 RS6 and RS7 front rotors only
Hats are not included; the Mercedes-Benz 390mm Front Replacement Rings reuse the hats already fitted
Dimpled hats from the A1-123DS rotor take the dimpled D1-123DS ring instead
Replace the rings at 34mm or if a crack reaches the edge
Stock photography may not depict the actual product

Frequently Asked Questions

Which rotors take the Mercedes-Benz 390mm Front Replacement Rings? The GiroDisc Mercedes-Benz 390mm Front Replacement Rings fit the hats of the A1-123 front rotor for the C63 AMG Black Series and the A1-190 front rotor for the C7 Audi RS6 and RS7. GiroDisc lists D1-123 as the replacement ring for both.
What thickness are the 390mm front rings when new? GiroDisc lists the ring at 36mm new with a minimum of 34mm, figures taken from its A1-190 rotor page. The minimum is also marked on the hat and the ring edge. Replace the pair at that point or if a crack runs to the outer edge.
Will these rings fit an Audi or Mercedes on factory rotors? No. They are designed only for GiroDisc hats. A car still on its factory discs has no hat to carry the ring, and factory two-piece hats or other brands use a different drive-pin arrangement, so the complete GiroDisc rotors must be fitted first.
Does an RS6 owner need anything else for a ring change? No. Each pair comes with replacement mounting hardware, so the iron and the fasteners are renewed together. The aluminum hats are the only parts carried over from the existing A1-190 rotors, and the job is done on the bench with standard tools.
Why does one ring serve both a Mercedes and an Audi? Both GiroDisc front rotors use a 390mm ring of the same thickness and vane design, so GiroDisc builds them around a common ring. That keeps the part in regular production and makes replacement rings easier to source for owners of either car.

About GiroDisc

GiroDisc designs, manufactures, and sells 2-piece, fully floating brake rotors for a wide range of performance vehicles. Every major component, including the hats, rotor rings, and drive pins, is manufactured in-house at their facility in Bellingham, Washington, from domestically sourced materials. GiroDisc rotors use a proprietary high-carbon iron ring formulated for superior metallurgy and thermal performance, paired with reusable machined-aluminum hats that reduce the long-term cost of maintaining a high-performance brake system. The 2-piece floating design sheds unsprung and rotating mass while remaining street-friendly, delivering race-proven braking for track and street use alike.

Additional Information

The Bulletproof Automotive website contains many thousands of products purchased in multiple different currencies. All of the prices are entered manually and accurately at the time of entry. Due to the consistently fluctuating international exchange rates, at times prices may not be able to be honored at their original intended rate. We apologize for any inconvenience this may cause, unfortunately our website is unable to compensate dynamically for what can at times be volatile changes in the cost of items due to currency values fluctuating, changes in prices from suppliers, changes in shipping and import duties, and other factors. Rest assured that any order you place on line will be at zero risk to you in this area. If in the event your order cannot be fulfilled at the original intended website price we will offer you a 100% refund, no questions asked. We will continue to do our best to maintain updated prices and we will always continue to offer our price match guarantees as well to ensure our prices are always the best for you. In short, prices may change without notice. It is always advised to give us a call prior to placing your order online to confirm availability and to confirm current pricing.

Shipping Policy

Items that are in stock in the US, either at Bulletproof’s warehouse or at a supplier’s warehouse, are generally delivered within 7-10 days. Special order items from overseas take considerably longer. As a courtesy Bulletproof offers delivery estimates to our customers which take into consideration manufacturer availability and shipping schedule. These estimates represent our best guess based on previous orders from the manufacturer and do not in any way imply a guaranteed delivery window. Many manufacturers work in a “just in time” inventory system and often take 2-20+ weeks to produce an item once an order is submitted. All deliverable items are then sent to our Japanese warehouse. Bulletproof ships a minimum of one full ocean freight container every month from Japan, oftentimes more than one a month. Ocean freight takes an average of 4 weeks. Typically it breaks down to one week in Japan for paperwork and customs, two weeks by boat and one week in US customs/clearance. Due to the wide number of variables between manufacturer and shipping schedules, delivery estimates are simply just that – estimates. We attempt to estimate conservatively and we usually deliver faster than our estimates suggest. It is not Bulletproof’s policy to guarantee delivery time of any special order item, this is impossible for us to do. By ordering you acknowledge that there is no required delivery ETA and an order may not be canceled or altered due to manufacturing or shipping delays, all ETA’s are provided as a best guess only. Please review the full Terms & Conditions here.

BP Pricing Difference

We do pricing a little differently on our JDM brands and we believe in making things simple and clear. No hidden fees or surcharges. Every price you see includes the shipping cost to our office in Los Angeles, California and all the associated taxes/duties/fees for bringing the products into the US. The only shipping you ever pay is from our facility in the US to your location. Be wary of resellers that don’t include the cost of international shipping in their pricing on JDM parts. While we believe we’ll always have the lowest all-in price on JDM products, we offer a price match guarantee for all authentic parts purchased from authorized dealers as well. For many international customers, it’s much more affordable to ship from the USA than from Japan directly, as the air freight and ocean freight costs are typically much less. However, for customers looking to ship directly from Japan outside of North America, or domestically in Japan, we can provide pricing specifically for that scenario. Please do not hesitate to contact us with any pricing questions or concerns. Please email us at sales@bulletproofautomotive.com with any inquiries.

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GiroDisc Mercedes-Benz 390mm Front Replacement Rings for C63 AMG Black Series and C7 Audi RS6 and RS7 [D1-123]

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GiroDisc Mercedes-Benz 390mm Front Replacement Rings for C63 AMG Black Series and C7 Audi RS6 and RS7

Fitment and Installation

Features

What’s Included

Applications

Notes

Frequently Asked Questions

About GiroDisc

Reviews