139-3214 Spindle Assembly Replaces Toro 121-0751 Spindle Assembly, 117-7439 Spindle, 117-7267, 139 3214, 121 0751, 117-7268 for Toro 42 50 inch SS5000 SS4225 SS4235 MX5060 MX5000 MX4250 Mowers

What It Is

This is a replacement spindle assembly for the cutting deck of select Toro residential zero-turn and lawn tractors. It houses the bearing and pulley that spin the blade, and it’s designed for 42-inch and 50-inch side-discharge decks.

Fitment & Compatibility

Before buying, confirm your deck model and spindle bolt pattern. This assembly replaces Toro OEM part numbers 121-0751, 117-7439, 117-7267, and 117-7268. It fits Toro SS5000, SS4225, SS4235, MX5060, MX5000, and MX4250 mowers with 42-inch or 50-inch fabricated decks. Measure the mounting hole spacing (typically 2.75 inches center-to-center) and the spindle shaft diameter (usually 1 inch). If your deck uses a different bolt pattern or shaft size, this won’t work. It’s an aftermarket part, not genuine Toro, but it’s a direct mechanical replacement.

Key Things to Know

• Installation difficulty: Moderate. You’ll need a socket set, a puller for the old spindle (if seized), and a torque wrench for the pulley nut (typically 45-55 ft-lbs). No special tools required.
• Quality: Aftermarket, but reviews suggest it holds up well under residential use. The bearings are sealed and pre-lubricated. Expect a lifespan of 2-4 seasons with regular maintenance.
• Common gotcha: The pulley and blade are not included. Reuse your existing pulley and blade or buy them separately. Also, check the blade bolt size (usually 5/8-inch or 3/4-inch) to ensure your blade fits the new spindle shaft.
• Fitment note: This spindle is for the left or center deck positions only. The right-hand spindle (with a different pulley offset) uses a different part number—verify your deck’s layout.

Should You Buy It

If you need a budget-friendly replacement for a worn or wobbly spindle on a Toro 42-inch or 50-inch residential mower, and you’re comfortable with a basic mechanical swap, this is a solid choice. It’s not for commercial use or decks outside the listed models, but for homeowner maintenance, it offers reliable performance at roughly half the cost of OEM.