GY20850 S100 42 Inch Mower Blades for John D-eere with 7 Star Mounting Pattern D100 D105 D110 D120 S110 S120 42'' Deck Lawn Tractor Riding Mower Replace GX22151 AM131033 (2 Pack)

What It Is

This is a 2-pack of 42-inch replacement blades for John Deere lawn tractors with a 7-star mounting pattern. Designed for mulching and bagging on mid-size residential mowing decks.

Fitment & Compatibility

Before buying, confirm your deck is exactly 42 inches (measured blade tip to tip). This set fits John Deere D100, D105, D110, D120, S100, S110, S120, and select other models with a 7-star center hole (not 5-point or oval). The OEM part numbers are GX22151 and AM131033—cross-check your model’s parts diagram. Measure your existing blade’s length, width, and thickness: these are typically 0.25 inches thick and 2.5 inches wide. Not compatible with 48-inch or 54-inch decks, or any non-Deere spindle pattern.

Key Things to Know

• Quality vs. OEM: Aftermarket blades may be slightly thinner or lighter steel than genuine Deere. Expect 1–2 seasons of residential use before dulling.
• Installation: Straightforward on most models—use a socket wrench and block the blade to prevent spinning. Torque to 40–50 ft-lbs. Ensure the 7-star pattern aligns fully; forcing can strip the spindle.
• Balance check: Aftermarket blades sometimes arrive unbalanced. Test spin on a balancer or nail before mounting; a minor wobble can cause vibration and deck damage.
• Sharpening: Can be sharpened once or twice, but the edge geometry may not match OEM for optimal cutting performance.

Should You Buy It

If you need a budget-friendly, functional replacement for a 42-inch John Deere residential mower and don’t mind checking balance yourself, this 2-pack is a solid value. For heavy commercial use or if you want maximum cut quality, stick with genuine Deere blades.