(4pcs) GX20377 GX21582 Tension Spring Mower Deck Belt Compatible with John Deere L120 L130 G110 145 155C 190C LA140 LA145 LA150 LA155 LA165 LA175 D140 D150 D155 D160 D170

What It Is

This is a set of four tension springs designed to maintain proper belt tension on the mower deck of select John Deere lawn tractors. They are essential for keeping the deck belt tight and aligned during operation, preventing slippage, uneven cuts, or belt damage.

Fitment & Compatibility

Before buying, confirm your mower’s model and deck size. These springs are listed for John Deere L120, L130, G110, 145, 155C, 190C, LA140, LA145, LA150, LA155, LA165, LA175, D140, D150, D155, D160, and D170 models. They replace OEM part numbers GX20377 and GX21582. However, deck size (e.g., 42”, 48”, 54”) can affect spring length and hook orientation. Measure your old spring’s overall length (hook to hook) and coil diameter. Also check if your deck uses two or four springs—some models only need two. Verify that the spring ends match your deck’s attachment points (round or flat hooks).

Key Things to Know

• Quality: These are aftermarket springs, not OEM. Most users report they work fine, but some note slightly lighter tension than originals. Check for corrosion resistance—some may rust faster.
• Installation: Easy to swap with basic hand tools (pliers, screwdriver). Use a spring puller or zip tie to safely stretch the spring onto the hook. Watch your fingers—springs can snap.
• Common Gotcha: If your mower has a multiple-belt deck, ensure you’re replacing the correct belt’s spring. Also, worn pulleys or a stretched belt can cause premature spring failure—inspect those first.
• Set Size: You get four springs, but not all decks need four. Check your deck diagram to avoid extras.

Should You Buy It

If you need a budget-friendly replacement for worn or broken deck tension springs on a compatible John Deere lawn tractor, this set is a solid choice. It’s ideal for DIY maintenance when you’re sure of fitment and don’t require OEM-grade durability. For heavy commercial use or if your deck has complex spring routing, consider OEM springs for guaranteed tension.