Sumo Gear 23-Spline RF1A Transfer Case Input Gear | 2.28:1 (1984-95 4Runner / 1979-95 Pickup)

Sumo Gear 23-Spline RF1A Transfer Case Input Gear

For 1984–1995 Toyota 4Runner and 1979–1995 Toyota Pickup 4WD with a 23-spline RF1A gear-driven transfer case

Overview

The Sumo Gear 23-Spline RF1A Transfer Case Input Gear is a stock-ratio replacement and conversion gear for Toyota RF1A gear-driven transfer cases. It uses a 23-spline input while retaining the factory-style 2.28:1 low-range ratio, making it suited to factory turbo applications and properly configured dual-case, crawl-box, and RF1A conversion builds.

Choose the standalone input gear when only the gear is needed, or choose the service bundle to add the transfer input-gear radial bearing and RF1A overhaul gasket kit while the case is apart.

Key Features

• 23-spline input for matching RF1A configurations
• Retains the factory-style 2.28:1 low-range ratio
• Designed for Toyota RF1A gear-driven transfer cases
• SCM420 alloy-steel construction
• Gear manufactured in Japan
• Available as the input gear alone or with complementary bearing and gasket service components

23-Spline Input & 2.28:1 Ratio

The factory Toyota 23-spline RF1A application is the 1986–1987 22R-TE Turbo 4Runner and Pickup with the R151F 5-speed manual transmission. Most naturally aspirated 20R, 22R, and 22RE RF1A applications use a 21-spline input and require the correct 23-spline conversion components before this gear can be used.

The gear retains the 2.28:1 factory-style low range. It does not convert the transfer case to a 4.7:1 crawl ratio.

Vehicle Fitment

Toyota 4Runner

• 1984–1989 Toyota 4Runner – 1st Gen – 4WD – RF1A Gear-Driven Transfer Case – 23-Spline Configuration
• 1990–1995 Toyota 4Runner – 2nd Gen – 4WD – RF1A Gear-Driven Transfer Case Conversion – 23-Spline Configuration

Toyota Pickup

• 1979–1983 Toyota Pickup – 1st Gen – 4WD – RF1A Gear-Driven Transfer Case – 23-Spline Conversion / Dual-Case Application
• 1984–1988 Toyota Pickup – 2nd Gen – 4WD – RF1A Gear-Driven Transfer Case – 23-Spline Configuration
• 1989–1995 Toyota Pickup – 3rd Gen – 4WD – RF1A Gear-Driven Transfer Case Conversion – 23-Spline Configuration

Factory 23-Spline Applications

• 1986–1987 Toyota 4Runner – 1st Gen – 22R-TE Turbo – R151F 5-Speed Manual – 4WD – RF1A Gear-Driven Transfer Case
• 1986–1987 Toyota Pickup – 2nd Gen – 22R-TE Turbo – R151F 5-Speed Manual – 4WD – RF1A Gear-Driven Transfer Case

Fitment Notes

• RF1A gear-driven transfer cases only.
• Requires a 23-spline input configuration.
• Most naturally aspirated 20R, 22R, and 22RE RF1A applications use a 21-spline input and require the correct 23-spline conversion hardware.
• Factory 3VZ-E V6 applications use a chain-driven transfer case. V6 vehicles require a properly configured RF1A conversion or dual-case system before using this gear.
• Modified and dual-case vehicles must be matched to the installed transfer-case type, spline count, transmission, adapter, and coupler configuration.
• Inspect the transfer-adapter oil seal during service and replace it separately when worn, hardened, damaged, leaking, or removed during disassembly.

Product Specifications

Brand: Sumo Gear
Product Type: Transfer Case Input Gear / Service Bundle
Transfer Case: Toyota RF1A Gear-Driven
Input Spline: 23 Spline
Low-Range Ratio: 2.28:1
Material: SCM420 Alloy Steel
Manufacturing: Japan
Drivetrain: 4WD

RF1A Identification & Low-Range Options

Use the RF1A Transfer Case Identification Guide to confirm transfer-case type, input spline, transmission, and shifter configuration before ordering. For a deeper low-range upgrade instead of the factory-style 2.28:1 ratio, see the Sumo Gear 4.7:1 RF1A Transfer Case Gear Set.

Available Configurations

23-Spline Input Gear

Includes:

• (1) 23-spline 2.28:1 RF1A transfer case input gear

Choose this configuration when only the input gear is needed.

Input Gear + Bearing & Gasket Service Bundle

Includes:

• (1) 23-spline 2.28:1 RF1A transfer case input gear
• (1) Transfer input-gear radial ball bearing
• (1) RF1A transfer case overhaul gasket kit

This configuration adds the main input bearing and overhaul gasket components for transfer-case service while replacing the input gear.

Important: The 23-spline transfer-adapter oil seal is not included in either configuration and must be sourced separately when replacement is needed.