RY401017 RY401018 Blade Mounting Assembly Compatible with Ryobi 20in Brushless 40v Lawnmower

What It Is

This is a blade mounting assembly (part numbers RY401017 and RY401018) that holds the blade securely to the spindle on Ryobi 20-inch brushless 40V lawn mowers. It replaces the original OEM assembly when the blade adapter, bolt, or washer wears out or gets damaged.

Fitment & Compatibility

Check your mower’s model number (on the deck or under the battery cover). This assembly fits Ryobi 20-inch brushless 40V mowers, including models like RY401140, RY401150, RY401160US, and RY401180. Will not fit gas-powered or 18V Ryobi mowers, or any deck smaller or larger than 20 inches. Measure the spindle diameter (typically 1 inch) and the bolt thread pitch (usually 5/16-24) to confirm. If your mower uses a different blade attachment system (e.g., a star-shaped adapter), this won’t work.

Key Things to Know

• Quality concerns: Reviews average 3.8/5; some users report the bolt or adapter warping after a few uses, especially on uneven terrain or with heavy grass. Consider a genuine Ryobi part if you mow frequently.
• Installation is straightforward: Remove the old assembly with a socket wrench (counterclockwise), then install the new one with the blade. Torque the bolt to 30-40 ft-lbs—over-tightening can strip threads.
• Common gotcha: The assembly includes a plastic adapter that can crack if the blade hits rocks or roots. Inspect it after each mow, and replace immediately if damaged to avoid blade detachment.
• Not a blade: This is just the mounting hardware. You still need a compatible 20-inch blade (Ryobi or aftermarket) to complete the setup.

Should You Buy It

Buy this if your Ryobi 40V 20-inch mower’s original mounting assembly is worn, bent, or missing, and you want a budget-friendly replacement. Skip it if you need a blade (separate purchase) or if you mow rough, debris-heavy lawns—the plastic adapter may not hold up as well as OEM. For occasional use on well-maintained grass, it’s a solid value.