Do the GiroDisc 390mm Front Replacement Rings fit the factory Mustang rotor hats?

No. The GiroDisc 390mm Front Replacement Rings are designed only for the hats of GiroDisc A1-343 front rotors on the S650 Mustang. They do not fit factory parts or hats from other two-piece rotor brands, so the GiroDisc rotors must already be on the car.

What comes in the box with the S650 front rings?

The box holds a left and a right ring plus a complete set of new drive pins and fasteners for both corners. The only parts reused from the car are the existing GiroDisc aluminum hats, which come off the hub with the old rings.

How do I know the front rings are worn out?

Measure the ring thickness with a micrometer. GiroDisc marks the 34mm minimum on the hat and the ring edge of the A1-343 assembly. Replace the pair at that figure or sooner if a crack reaches the outer edge of either ring.

Which rings go on the rear of the same S650?

The rear axle uses GiroDisc D2-343, a 355mm by 28mm ring with 48 curved vanes and a 26mm minimum thickness. It fits only the hats of the GiroDisc A2-343 rear rotors used with the four-piston Brembo rear calipers, and it is also sold as a pair with hardware.

Are the S650 front rings sold individually?

No. GiroDisc sells these rings only as a matched pair, one left handed and one right handed, each labeled for its side. Buying them together keeps both front corners on identical iron with the same vane direction and the same starting thickness, which makes later wear checks simple and consistent.

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Description

GiroDisc 390mm Front Replacement Rings for S650 Ford Mustang

GiroDisc’s 390mm Front Replacement Rings renew the friction surfaces on a set of GiroDisc S650 Mustang front rotors without replacing the aluminum hats. Each ring is 390mm in diameter and 36mm thick, with 72 curved vanes, cast from GiroDisc’s high-carbon iron and machined in Bellingham, Washington. The pair arrives with new mounting hardware, so a worn set is refreshed for a fraction of what complete assemblies cost. It suits the Dark Horse or GT Performance Package owner who does enough track days to wear through rings each season.

Fitment and Installation

The rings bolt to existing GiroDisc S650 front hats with the drive pins and cap screws supplied. Cap screws are never tightened past 60 in-lb, or 7 Nm, so the ring can float. GiroDisc rings are only designed for GiroDisc hats; hats from other brands, or factory two-piece hats, will not accept them.

Features

Machined to 390mm by 36mm with a 34mm wear limit
72 curved internal vanes
Proprietary high-carbon iron, poured in the USA
Fresh drive pin hardware included with the pair
Left and right handed rings, labeled by position
Slotted face for a clean friction surface

What’s Included

Front replacement rings (L/R)
Replacement mounting hardware

Applications

Ford Mustang Dark Horse: S650 | 5.0L V8
Ford Mustang Dark Horse SC: S650
Ford Mustang GT with Performance Package: S650 | 5.0L V8

Notes

The GiroDisc 390mm Front Replacement Rings fit the hats of the GiroDisc S650 front rotors only; hats are not included
The rear axle uses the GiroDisc S650 rear replacement rings
Rings are sold as a pair
Stock photography may not depict the actual product

Frequently Asked Questions

Do the GiroDisc 390mm Front Replacement Rings fit the factory Mustang rotor hats? No. The GiroDisc 390mm Front Replacement Rings are designed only for the hats of GiroDisc A1-343 front rotors on the S650 Mustang. They do not fit factory parts or hats from other two-piece rotor brands, so the GiroDisc rotors must already be on the car.
What comes in the box with the S650 front rings? The box holds a left and a right ring plus a complete set of new drive pins and fasteners for both corners. The only parts reused from the car are the existing GiroDisc aluminum hats, which come off the hub with the old rings.
How do I know the front rings are worn out? Measure the ring thickness with a micrometer. GiroDisc marks the 34mm minimum on the hat and the ring edge of the A1-343 assembly. Replace the pair at that figure or sooner if a crack reaches the outer edge of either ring.
Which rings go on the rear of the same S650? The rear axle uses GiroDisc D2-343, a 355mm by 28mm ring with 48 curved vanes and a 26mm minimum thickness. It fits only the hats of the GiroDisc A2-343 rear rotors used with the four-piston Brembo rear calipers, and it is also sold as a pair with hardware.
Are the S650 front rings sold individually? No. GiroDisc sells these rings only as a matched pair, one left handed and one right handed, each labeled for its side. Buying them together keeps both front corners on identical iron with the same vane direction and the same starting thickness, which makes later wear checks simple and consistent.

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 390mm Front Replacement Rings for S650 Ford Mustang [D1-343]

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GiroDisc 390mm Front Replacement Rings for S650 Ford Mustang

Fitment and Installation

Features

What’s Included

Applications

Notes

Frequently Asked Questions

About GiroDisc

Reviews