M127926 Mower Timing Belt for John Deere LT133 and LT155 Serial No. 125001 and Lower, LT166 Serial No. 095001 and Lower, 5/8 x 71 Inch Freedom 42 Deck M127926 Timing Synchronous Belt

What It Is

This is a replacement timing synchronous belt for the Freedom 42 deck on specific John Deere LT133, LT155, and LT166 lawn tractors. It drives the blade engagement system, synchronizing the two spindles to keep blades spinning in time.

Fitment & Compatibility

Before buying, confirm your mower’s serial number range: LT133 and LT155 must be serial no. 125001 and lower; LT166 must be serial no. 095001 and lower. This belt fits the 42-inch Freedom deck only (not the Edge or other decks). Measure your old belt—it should be 5/8 inch wide and 71 inches long. This is an aftermarket belt, not OEM John Deere, but it matches the original M127926 part number. Double-check that your deck uses a single timing belt (not two separate belts) and that your spindles have timing pulleys, not standard V-pulleys.

Key Things to Know

• Quality: Most users report it’s a solid aftermarket alternative to OEM, with similar durability for residential use. Some note it can be slightly stiffer than OEM, requiring a break-in period.
• Installation difficulty: Moderate. You’ll need to remove the deck, release belt tension (usually a spring-loaded idler), and route the belt around both spindles and the idler pulley. A diagram under the deck or in your manual helps.
• Common gotchas: If your mower has a higher serial number than listed, this belt will not fit—the deck design changed. Also, check that your blade spindles turn freely; seized spindles will quickly ruin a new belt.
• Timing marks: Ensure the belt’s teeth align with pulley grooves. Misalignment causes vibration or belt slip.

Should You Buy It

If you own a compatible LT133, LT155, or LT166 with a Freedom 42 deck and need a reliable, cost-effective replacement, this belt is a solid choice. It’s not for newer models or non-Freedom decks, but for the right machine, it’s a straightforward fix that saves you roughly 40% vs. OEM.