Which cars use the GiroDisc 380x30mm Rear Replacement Rings?

The GiroDisc 380x30mm Rear Replacement Rings suit Porsche 991 GT3 Cup and Cayman GT4 Clubsport race cars that already run GiroDisc rear rotors, part numbers A2-238 and A2-266. The rings mount to those GiroDisc hats only and do not fit factory or third-party hats.

Are the Cup rear rings thinner than the fronts?

Yes. The rear ring is 30mm thick on a 380mm diameter, while the matching front ring, GiroDisc D1-238, is 32mm thick on the same diameter. Keep the two part numbers separate in the spares box, because neither ring is meant for the other axle.

Does the rear ring kit include drive pins?

Yes. Every pair comes with new cadmium-plated alloy steel drive pins, class 12.9 cap screws with hardened washers and anti-noise spring washers for both corners. The GiroDisc aluminum hats are the only components reused from the worn rotors, so the rear axle is back together quickly between sessions.

What signs mean the rear Cup rings are finished?

GiroDisc advises replacing the rings once they reach the minimum thickness marked on the hat and ring edge. A crack that runs from the friction face out to the edge of a ring also means the pair should come off the car immediately.

Why are GiroDisc rear rings handed left and right?

The curved vanes are angled so they pump air outward only when the disc turns in its intended direction. GiroDisc therefore makes a left ring and a right ring and labels both, and fitting each to the marked side keeps the cooling working as designed.

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Description

GiroDisc 380x30mm Rear Replacement Rings for 991 Porsche 911 GT3 Cup and Cayman GT4 Clubsport

GiroDisc’s 380x30mm Rear Replacement Rings re-iron the rear GiroDisc rotors on the 991 GT3 Cup and the Cayman GT4 Clubsport. A single ring design covers both cars, mounting to the aluminum hats already on the axle and arriving as a pair with fresh drive pin hardware. The rings are cast from GiroDisc’s own iron in the USA and machined start to finish at the GiroDisc facility. Race teams and track-day regulars on either chassis who want to keep spares simple will find this the obvious rear ring to stock.

Construction

Inside each 30mm ring is a curved vane core, a racing-derived design that acts as a centrifugal pump to push cooling air out through the disc. The kit’s cadmium-plated drive pins resist corrosion, and the anti-noise spring washers let the ring grow with heat without rattling when cold.

Features

380mm by 30mm rear ring
Shared between the 991 Cup and GT4 Clubsport rear rotors
Curved vane cooling core
Proprietary cast iron, machined in-house
Complete pin, screw and spring washer kit for both corners

What’s Included

Rear replacement rings (L/R)
Replacement mounting hardware

Applications

Porsche 911 GT3 Cup: 991 | Factory race car
Porsche Cayman GT4 Clubsport: Factory race car

Notes

The GiroDisc 380x30mm Rear Replacement Rings fit only the hats of the GiroDisc 991 GT3 Cup rear rotors and the GiroDisc GT4 Clubsport rear rotors; hats are not included
Front corners use the GiroDisc 380x32mm front replacement rings
Factory two-piece hats and other brands are not compatible
Stock photography may not depict the actual product

Frequently Asked Questions

Which cars use the GiroDisc 380x30mm Rear Replacement Rings? The GiroDisc 380x30mm Rear Replacement Rings suit Porsche 991 GT3 Cup and Cayman GT4 Clubsport race cars that already run GiroDisc rear rotors, part numbers A2-238 and A2-266. The rings mount to those GiroDisc hats only and do not fit factory or third-party hats.
Are the Cup rear rings thinner than the fronts? Yes. The rear ring is 30mm thick on a 380mm diameter, while the matching front ring, GiroDisc D1-238, is 32mm thick on the same diameter. Keep the two part numbers separate in the spares box, because neither ring is meant for the other axle.
Does the rear ring kit include drive pins? Yes. Every pair comes with new cadmium-plated alloy steel drive pins, class 12.9 cap screws with hardened washers and anti-noise spring washers for both corners. The GiroDisc aluminum hats are the only components reused from the worn rotors, so the rear axle is back together quickly between sessions.
What signs mean the rear Cup rings are finished? GiroDisc advises replacing the rings once they reach the minimum thickness marked on the hat and ring edge. A crack that runs from the friction face out to the edge of a ring also means the pair should come off the car immediately.
Why are GiroDisc rear rings handed left and right? The curved vanes are angled so they pump air outward only when the disc turns in its intended direction. GiroDisc therefore makes a left ring and a right ring and labels both, and fitting each to the marked side keeps the cooling working as designed.

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 380x30mm Rear Replacement Rings for 991 Porsche 911 GT3 Cup and Cayman GT4 Clubsport [D2-238]

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GiroDisc 380x30mm Rear Replacement Rings for 991 Porsche 911 GT3 Cup and Cayman GT4 Clubsport

Construction

Features

What’s Included

Applications

Notes

Frequently Asked Questions

About GiroDisc

Reviews