What ratios does the 3-Speed Close Ratio Gear Kit for FC3S RX-7 use?

The 3-Speed Close Ratio Gear Kit for FC3S RX-7 uses 2.714, 1.742 and 1.267 for first to third, with fourth and fifth staying factory. OS Giken Japan lists the factory ratios as 3.483 / 2.015 / 1.391 / 1.000 / 0.806.

Does it need any other parts?

Yes. OS Giken Japan lists Mazda spacer R502-17-316 and roller bearing R502-17-306A as required. The kit is mostly a direct replacement, so the factory gearbox manual is followed for assembly. Our team can help with any questions. Our team can help confirm both before ordering.

Will it fit the other RX-7 gearbox?

No. OS Giken Japan says the FC3S and FD3S kits are not interchangeable. The input shafts differ in length and the FD3S uses double-synchro gears, so order the kit listed for your chassis. Our team can help with any questions.

Are the gears noisy like a race gearbox?

No. OS Giken cuts these gears helically rather than straight-cut, which keeps operation quiet and smooth enough for street driving while staying reliable for racing. The shift feel stays close to the factory gearbox because the kit uses the factory casing.

How is the kit installed?

The gearbox is rebuilt with the OS Giken gears in place of the factory parts, following the factory service manual for the car. OS Giken describes its gear kits as competition parts, so have the work done by a shop experienced with this gearbox.

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Description

OS Giken 3-Speed Close Ratio Gear Kit for FC3S RX-7 Mazda RX-7 R5M-D

OS Giken’s 3-Speed Close Ratio Gear Kit for FC3S RX-7 rotaries replaces first, second and third in the R5M-D five-speed with closer OS Giken ratios of 2.714, 1.742 and 1.267, against factory ratios of 3.483 / 2.015 / 1.391 / 1.000 / 0.806 as OS Giken Japan lists them. OS Giken USA says its close ratio gear kits are researched and designed for each engine’s intended racing application, with ratios chosen to keep the engine in its peak power band so the car keeps accelerating as efficiently as possible.

Built for the Rotary Power Band

The 3-Speed Close Ratio Gear Kit for FC3S RX-7 rotaries keep the 13B nearer its peak power on each upshift. Each gear is made from forged material and then hard shot peened for strength and durability, and the gears are helical-cut rather than straight-cut to keep operation quiet and smooth on the street while staying reliable for racing.

Features

Closer first, second and third gears
For the FC3S RX-7 R5M-D gearbox
Forged gears, hard shot peened for strength
Helical-cut for quiet, smooth operation
Ratios chosen to keep the engine in its power band

Specifications

1st gear: 2.714 (factory 3.483)
2nd gear: 1.742 (factory 2.015)
3rd gear: 1.267 (factory 1.391)
4th gear: factory 1.000
5th gear: factory 0.806

Applications

Mazda RX-7: FC3S | 1986-1992 | 1.3L rotary, R5M-D five-speed

Notes

OS Giken Japan lists genuine Mazda parts R502-17-316 (spacer) and R502-17-306A (roller bearing) as required with this kit
OS Giken Japan notes that FC3S and FD3S kits are not interchangeable; the input shafts differ in length and the FD3S uses double-synchro gears
OS Giken describes its gear kits as competition parts
Installation labor is not included

Frequently Asked Questions

What ratios does the 3-Speed Close Ratio Gear Kit for FC3S RX-7 use? The 3-Speed Close Ratio Gear Kit for FC3S RX-7 uses 2.714, 1.742 and 1.267 for first to third, with fourth and fifth staying factory. OS Giken Japan lists the factory ratios as 3.483 / 2.015 / 1.391 / 1.000 / 0.806.
Does it need any other parts? Yes. OS Giken Japan lists Mazda spacer R502-17-316 and roller bearing R502-17-306A as required. The kit is mostly a direct replacement, so the factory gearbox manual is followed for assembly. Our team can help with any questions. Our team can help confirm both before ordering.
Will it fit the other RX-7 gearbox? No. OS Giken Japan says the FC3S and FD3S kits are not interchangeable. The input shafts differ in length and the FD3S uses double-synchro gears, so order the kit listed for your chassis. Our team can help with any questions.
Are the gears noisy like a race gearbox? No. OS Giken cuts these gears helically rather than straight-cut, which keeps operation quiet and smooth enough for street driving while staying reliable for racing. The shift feel stays close to the factory gearbox because the kit uses the factory casing.
How is the kit installed? The gearbox is rebuilt with the OS Giken gears in place of the factory parts, following the factory service manual for the car. OS Giken describes its gear kits as competition parts, so have the work done by a shop experienced with this gearbox.

About OS Giken

OS Giken was founded in Okayama, Japan in 1973 by Masaharu Okazaki. It built the TC16 and TC24-B1 DOHC cylinder heads for Nissan L-series engines, began making multi-plate racing clutches in 1982 and started supplying OEM limited-slip differentials in 1983. Development of the Super Lock LSD began in 1997, and of the OS-88 sequential gearbox for the Skyline GT-R in 1998.

Additional Information

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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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OS Giken 3-Speed Close Ratio Gear Kit for FC3S RX-7 Mazda RX-7 R5M-D [MZ111-GA]

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OS Giken 3-Speed Close Ratio Gear Kit for FC3S RX-7 Mazda RX-7 R5M-D

Built for the Rotary Power Band

Features

Specifications

Applications

Notes

Frequently Asked Questions

About OS Giken

Reviews