GX25628 Belt Replacement for John Deere 42 Inch Mower Deck Belt Z335E Z315E, Z320M, Z320R, Z335M, Z345M

What It Is

The GX25628 is an aftermarket V-belt replacement for the primary drive belt on John Deere Z300 series zero-turn mowers with a 42-inch fabricated deck. It connects the engine pulley to the deck spindles, enabling blade rotation.

Fitment & Compatibility

• Deck size: Only fits John Deere 42-inch fabricated (not stamped) decks.
• Models: Z335E, Z315E, Z320M, Z320R, Z335M, Z345M. Confirm your model number on the frame tag—Z300 series with other deck sizes will not work.
• OEM cross: Replaces John Deere part GX25628. Verify your old belt’s part number or measure length (about 92.5 inches outside circumference, 1/2 inch width).
• Measure before buying: If your old belt is stretched or broken, measure the deck belt path with a string to confirm length. Aftermarket belts can vary slightly in tension.

Key Things to Know

• Quality vs OEM: This aftermarket belt costs about half of a John Deere OEM belt. Users report similar durability for residential use, but commercial operators may prefer OEM for longer life.
• Installation: Moderate difficulty—requires removing the deck (two pins, belt tension release). Watch a model-specific video; routing is tight around the idler pulley.
• Common gotcha: If your mower vibrates or throws the belt after replacement, check that the belt is seated in all pulley grooves and the tensioner spring is correctly hooked.
• Warranty: No manufacturer warranty listed—buy from a seller with a return policy in case of premature wear or sizing issues.

Should You Buy It

If you own a John Deere Z300 with a 42-inch fabricated deck and want a budget-friendly belt for occasional residential mowing, this is a solid pick. For heavy commercial use or if you prefer exact OEM fitment, stick with the John Deere GX25628.