Caltric Deck Blade with Lock Nut Compatible with John Deere S100 S110 S120 100 Series 42" Tractor

What It Is

The Caltric Deck Blade with Lock Nut is a replacement blade set for 42-inch cutting decks on select John Deere 100 Series lawn tractors, designed to swap worn or damaged blades for a clean, even cut.

Fitment & Compatibility

• Deck size: Fits 42-inch decks only—measure your deck width to confirm.
• Models: Compatible with John Deere S100, S110, S120, and other 100 Series tractors (e.g., D100, D105, D110, D120, D125, D130, D140, D150, D155, D160, D170, LA105, LA115, LA125, LA135, LA145, LA155, LA165, L100, L110, L118, L120, L130). Check your model’s year range (typically 2000s–2010s).
• OEM cross-reference: Replaces John Deere parts GY20785, GY20872, GY20930, GY20931, GY20932, GY21142, GY21145, and others.
• Measurements: Blade length 20.5 inches, center hole 5/8 inch, thickness 0.2 inches. Verify your existing blade dimensions before ordering.
• Includes: Two blades and two lock nuts. Does not include a center bolt or washer.

Key Things to Know

• Quality: Caltric is an aftermarket brand. Expect decent steel and edge retention, but not OEM longevity. Some users report slight imbalance out of box.
• Installation: Moderate difficulty—requires lifting the mower, removing the blade bolt (often stuck), and torquing the lock nut to 40–50 ft-lbs. Use a blade removal tool or block of wood to prevent spinning.
• Common gotcha: The included lock nuts are nylon-insert type and single-use. Replace them each time you change blades.
• Sharpening: Can be sharpened, but the blade is not heat-treated for repeated grinding—replace when nicked or dull.

Should You Buy It

Buy this if you need a budget-friendly replacement for a 42-inch John Deere 100 Series mower and don’t mind a slight reduction in cut quality or lifespan compared to OEM blades. It’s a solid value for occasional home use but skip it for heavy-duty commercial mowing.