What is a close ratio gear kit and why would I want one?

A close ratio gear kit changes the factory gear ratios in your transmission to have smaller steps between each gear. This helps keep your engine, especially a rotary like the 13BT, in its ideal power band more often during acceleration, leading to quicker response and better performance on the track.

Does this kit include everything needed for the transmission rebuild?

This kit includes the specific gears required for the close ratio modification. However, a transmission rebuild typically requires additional items such as new seals, gaskets, and appropriate transmission fluid, which are not included with this gear set.

Is this a difficult installation?

Installing a close ratio gear kit involves a complete transmission rebuild. This is a complex job that requires specialized tools and mechanical expertise. It is recommended to have this service performed by a qualified mechanic experienced with rotary engines and transmissions.

1986-1991 Mazda RX-7 Close Ratio Gear Kit

Name: OS Giken Mazda RX7 FC3S 13BT 3 Speed Close Ratio Gear Kit
Brand: OS Giken
SKU: os-giken-os-giken-mazda-rx7-fc3s-13bt-3-speed-close-ratio-gear-kit-t14-446272
Price: 2730.24 USD
Availability: BackOrder

OS Giken Mazda RX7 FC3S 13BT 3 Speed Close Ratio Gear Kit

$2730.24

On Backorder

Order now to reserve yours — we'll ship as soon as stock arrives. Full refund if we're unable to fulfill.

OS Giken Mazda RX7 FC3S 13BT 3 Speed Close Ratio Gear Kit fits 1986-1991 Mazda RX-7.

Key Features

Fits 1986-1991 Mazda RX-7.
Designed for the 13BT rotary engine.
Provides closer gear ratios for improved acceleration.
Helps keep the engine within its optimal RPM range during shifts.
A performance upgrade for track use and spirited driving.
Includes all necessary gears for the transmission modification.

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Product Details

This OS Giken 3-speed close ratio gear kit is specifically for the 1986-1991 Mazda RX-7 with the 13BT rotary engine. If you're looking to get the most out of your RX-7's performance, especially for track use or spirited driving, changing the gear ratios can make a significant difference in how the car accelerates and stays in its power band. This kit updates the factory transmission gearing to provide closer steps between each gear, meaning your engine will spend more time in its optimal RPM range during acceleration.

OS Giken is well-known for producing robust drivetrain components, and this gear kit is no exception. The close ratio design is engineered to keep the rotary engine's power delivery consistent, reducing the RPM drop between shifts. This is particularly beneficial for turbocharged rotary engines, which often have a narrow power band. The kit includes all the necessary gears to modify your transmission for this improved performance. Installation involves rebuilding the transmission, so it's a job that requires specialized knowledge and tools. It's a substantial upgrade for RX-7 owners serious about optimizing their vehicle's acceleration and track performance.

When undertaking a transmission rebuild for this gear kit, it's important to have all your components ready. Ensure you have the correct transmission fluid and any other seals or gaskets needed for the rebuild process. OS Giken's focus on performance means this kit is built to handle the demands of a rotary engine, offering a way to significantly enhance your RX-7's driving dynamics.