Deck Belt 1/2" x 118.3" Made with Kevlar for John Deere GX25628 Z335E Z335M Z345M Z345R with 42" Deck

What It Is

This is a replacement deck belt for 42-inch cutting decks on select John Deere Z300 Series zero-turn mowers. Constructed with Kevlar reinforcement, it drives the blades from the engine pulley and is designed for residential mowing use.

Fitment & Compatibility

Before buying, verify your mower model and deck size exactly. This belt fits John Deere models Z335E, Z335M, Z345M, and Z345R—all with 42-inch decks. The OEM part number is GX25628. Measure your old belt: it must be 1/2 inch wide and 118.3 inches long. Aftermarket belts like this one can work, but confirm the cross-section matches (single-wrapped, not cogged) and that the tensioner spring/pulley alignment is correct. Check your deck serial number plate for accuracy.

Key Things to Know

• Quality: Kevlar construction improves durability over standard rubber belts, reducing stretching and breakage under load.
• Installation difficulty: Moderate. You’ll need to remove the deck or access the belt path from below. A belt routing diagram is helpful—take a photo before removing the old belt.
• Common gotcha: The belt must be routed correctly around all pulleys and idlers; incorrect routing causes slipping or premature wear. Also, check pulley bearings for roughness while you’re at it.
• Lifespan: Expect 100–200 hours of mowing, depending on debris and tension. Inspect annually.

Should You Buy It

If you own one of the listed John Deere Z300 models with a 42-inch deck and need a reliable, budget-friendly replacement that outperforms basic rubber belts, this is a solid choice. It’s not OEM but uses quality Kevlar construction, making it a good value for residential mowing. Avoid if you have a different deck size or need a belt for heavy commercial use.