3mirrors Engine Shaft Sleeve Adapter 1.000" to 1.125" Stainless SS304 — 1.5" Extension, 1/4" Key

3mirrors Engine Pulley Crank Shaft Sleeve Adapter converts a 1.000" crankshaft to 1.125" and extends the shaft 1.5" to accept larger pulleys or gearboxes.

When you need to fit a larger pulley, gearbox input, or transfer case to an existing gas engine crank without replacing the motor, this stainless-steel sleeve adapter provides a simple, robust solution. CNC-machined from SS304 for corrosion resistance and precision fit, the adapter set includes grade 12.9 fasteners and a washer so you can install it on most 1" crankshafts using the 1/4" keyway.

How does this adapter change pulley size or gear ratio?

By increasing the crankshaft diameter from 1.000" to 1.125", the adapter lets you mount pulleys and gears designed for the larger diameter. That change alters pulley circumference and belt path, enabling different speeds or mechanical advantages without swapping the engine.

• Converts 1.000" shaft to 1.125" shaft diameter
• Extends shaft length by 1.5" for clearance or multi-pulley setups
• Uses existing 1/4" keyway to transmit torque reliably
• Saves cost versus buying a new motor or special pulley

Will this fit my gas engine crankshaft and pulley setup?

The sleeve is made for standard 1.000" engine cranks with a 1/4" keyway. It is intended for common small gas engines where pulleys or gearbox inputs expect a 1.125" shaft. Check your crank diameter and key size before ordering.

• Intended for 1" crankshafts with 1/4" keyway
• Ideal where pulley or gearbox bores are 1.125"
• Includes two high-strength bolts (3/8-24 and 7/16-20) plus washer
• Verify bolt engagement depth and key clearance on your engine

What makes SS304 and CNC machining important for this adapter?

SS304 stainless steel offers corrosion resistance and strength for outdoor and workshop environments; CNC machining ensures concentricity and tight tolerances for smooth pulley runout. Those qualities reduce belt wear and vibration compared with rough or plated alternatives.

• SS304 resists rust and holds finish over time
• CNC machining achieves precise inner and outer diameters
• Accurate fit reduces eccentricity and vibration on rotating parts
• Recommended for applications where alignment and longevity matter

How is the adapter secured and what hardware is included?

The adapter set ships with two high-grade fasteners and a washer so you can clamp it to the crank and retain pulleys safely. Both bolts are 12.9 grade for high tensile strength; use appropriate thread engagement and torque settings for your engine.

• Comes with one 3/8-24 bolt and one 7/16-20 bolt
• Includes a washer sized for the smaller bolt to ensure even seating
• 12.9-grade hardware provides high clamping reliability
• Follow engine manufacturer torque specs to avoid over-tightening

Who is this for: this 3mirrors shaft sleeve adapter is built for mechanics, hobbyists, and small-engine technicians who want to adapt existing gas engines to larger pulleys or gearboxes without replacing the motor. It suits lawn, garden, and light industrial applications where a precise, rust-resistant shaft increase and modest extension are required. If you need to change pulley diameter, add clearance for accessories, or maintain existing belt-driven systems while upgrading driven components, this adapter provides a cost-effective, durable option.