Which race cars do the GiroDisc 355mm Front Rotors for S197 fit?

The 355mm Front Rotors for S197 are listed by GiroDisc for the Ford Mustang FR500S and the Boss 302S, both factory-built racing versions of the S197. Road-going Mustangs use other GiroDisc rotors, so match the part to your car before ordering.

Do these rotors require new calipers or brackets?

No. GiroDisc builds them as a direct replacement for the factory discs, so the original calipers and brackets are reused without modification. That keeps the brake bias and ABS efficiency as the car was developed, which matters when a team has its setup dialed in.

What does the two-piece design do for lap times?

It removes rotating and unsprung weight from each front corner, which helps the car accelerate and lets the suspension respond faster over curbs and bumps. The floating ring also resists heat distortion, so braking stays consistent through a long stint.

Why do the cap screws appear loose?

The iron ring floats on the hat so it can expand with heat without warping. GiroDisc tightens the cap screws to no more than 60 in-lb, and the slight free play that results is intentional. The screws should never be tightened further.

Does GiroDisc recommend drilled rotors for racing?

No. GiroDisc does not recommend drilled discs for performance use, because drilling can lead to cracks under repeated heat cycles. Its rotors use slots, which keep the friction surface clean and stop a water film forming in wet sessions without weakening the ring.

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Description

GiroDisc 355mm Front Rotors for S197 Ford Mustang FR500S and Boss 302S

GiroDisc’s 355mm Front Rotors for S197 Ford Mustang FR500S and Boss 302S race cars replace the factory front discs with a two-piece floating assembly. The ring is GiroDisc’s proprietary cast iron, poured in the USA and machined start to finish in Bellingham, Washington, and it floats on a hat of US-sourced 6061-T6 aircraft-specification aluminum. Cutting rotating and unsprung weight sharpens acceleration and suspension response, both of which show up on a lap time. For a team running one of these factory-built racers, they are a straightforward front brake upgrade.

Bolt-On and Go

The rotors are a direct replacement for the original discs, so they bolt on with no modifications and the factory calipers are retained. Keeping the stock setup preserves the brake bias and ABS efficiency the car was developed with, which a big brake kit would change. Grade 12 cap screws with hardened washers secure the cadmium-plated alloy steel drive pins.

Features

355mm front rotor for the FR500S and Boss 302S
Two-piece floating design that cuts rotating and unsprung mass
US-sourced 6061-T6 aluminum hat
Proprietary cast iron ring poured in the USA
Cadmium-plated alloy steel drive pins with grade 12 cap screws
Curved vanes that pump air through the ring

What’s Included

Front rotor assemblies (L/R)

Applications

Ford Mustang Boss 302S: S197 race car
Ford Mustang FR500S: S197 race car

Notes

The 355mm Front Rotors for S197 suit the FR500S and Boss 302S race cars named by GiroDisc
Road-going Brembo S197 models use the GiroDisc S197 front rotors
Cap screws can look loose by design and are never tightened beyond 60 in-lb (7 Nm)
Stock photography may not depict the actual product

Frequently Asked Questions

Which race cars do the GiroDisc 355mm Front Rotors for S197 fit? The 355mm Front Rotors for S197 are listed by GiroDisc for the Ford Mustang FR500S and the Boss 302S, both factory-built racing versions of the S197. Road-going Mustangs use other GiroDisc rotors, so match the part to your car before ordering.
Do these rotors require new calipers or brackets? No. GiroDisc builds them as a direct replacement for the factory discs, so the original calipers and brackets are reused without modification. That keeps the brake bias and ABS efficiency as the car was developed, which matters when a team has its setup dialed in.
What does the two-piece design do for lap times? It removes rotating and unsprung weight from each front corner, which helps the car accelerate and lets the suspension respond faster over curbs and bumps. The floating ring also resists heat distortion, so braking stays consistent through a long stint.
Why do the cap screws appear loose? The iron ring floats on the hat so it can expand with heat without warping. GiroDisc tightens the cap screws to no more than 60 in-lb, and the slight free play that results is intentional. The screws should never be tightened further.
Does GiroDisc recommend drilled rotors for racing? No. GiroDisc does not recommend drilled discs for performance use, because drilling can lead to cracks under repeated heat cycles. Its rotors use slots, which keep the friction surface clean and stop a water film forming in wet sessions without weakening the ring.

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 355mm Front Rotors for S197 Ford Mustang FR500S and Boss 302S [A1-112]

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GiroDisc 355mm Front Rotors for S197 Ford Mustang FR500S and Boss 302S

Bolt-On and Go

Features

What’s Included

Applications

Notes

Frequently Asked Questions

About GiroDisc

Reviews