GX20072 GY20570 Lawn Mower Deck Belt - 42" for John Deere GY20570 L 100 130 1742 D 100 110 120 130 X 110 125 145 LA 105 D100 D105 D110 D120 D125 D130 E100 E110 E120

What It Is

This is a 42-inch lawn mower deck drive belt (model GX20072, cross-referenced as GY20570) that transfers power from the engine pulley to the mower blades. It’s designed for select John Deere 100-series, LA-series, and X-series riding mowers with a 42-inch stamped deck.

Fitment & Compatibility

Before buying, confirm your mower has a 42-inch deck (measure deck width or check model tag). Compatible John Deere models include: L100, L130, D100, D105, D110, D120, D125, D130, E100, E110, E120, LA105, X110, X125, X145, and 1742. Also fits some older L-series and D-series with the same 42-inch deck. This is an aftermarket replacement for OEM part GY20570. Measure your old belt length (should be ~91.5 inches) and count the number of grooves (typically 4 or 5) to ensure match. Check deck pulley alignment and belt routing diagram under the deck or in your manual—wrong routing will cause slipping or blade disengagement.

Key Things to Know

• Quality vs. OEM: At $14.88, this is a budget-friendly option. Some users report shorter lifespan than John Deere OEM belts, especially under heavy use or in wet grass.
• Installation difficulty: Moderate. You’ll need a wrench to remove the deck or access the belt tensioner. No special tools required, but allow 30–45 minutes for first-time install.
• Common gotchas: The belt may be slightly narrower or looser than OEM—tighten the tensioner fully and check for squealing after first use. Also, verify the belt is routed outside all idler pulleys (a common mistake that leads to rapid wear).
• Check deck spindle bearings: If your old belt broke or wore unevenly, inspect spindles for wobble or seized bearings—bad spindles will kill a new belt quickly.

Should You Buy It

If you need a quick, low-cost replacement for a residential mower used on a standard lawn (not commercial or heavy-duty), this belt will get the job done. It’s a solid budget pick for occasional mowing, but if you mow frequently, thick grass, or large areas, consider spending more on an OEM belt for longer life and better fit.