UDC Parts M110978 Drive Belt Replacement for John Deere LX176 LX188 LX178 LX172 LX173 LX186 / Aramid Cord Powertrain Drive V-Belt / 102.00 inches

What It Is

The UDC M110978 is an aftermarket aramid cord drive belt designed to replace the OEM John Deere M110978 powertrain V-belt. It connects the engine pulley to the transmission on select John Deere LX and X series lawn tractors, enabling forward and reverse motion. This is a drive belt, not a mower deck belt.

Fitment & Compatibility

Confirm your model before ordering. This belt fits these John Deere tractors: LX172, LX173, LX176, LX178, LX186, LX188, and the X300 series (X300, X304, X320, X324, X340, X360).
Critical checks:

• Measure your existing belt length: this belt is 102.00 inches (outside circumference). If your original is shorter or longer, this will not fit.
• Verify you have a hydrostatic or manual transmission – this belt works with both on these models, but not with K46 or other non-JD transmissions.
• OEM part number: M110978. Aftermarket belts like this UDC are cross-referenced by size, not brand. If your tractor uses a different OEM belt number, check the 102-inch spec.

Key Things to Know

• Aramid cord construction is stronger than standard rubber belts – resists stretching and snapping under load, especially on hills or with heavy baggers.
• Installation is moderate difficulty (2/5). You’ll need to remove the mower deck, release the belt tensioner, and route the belt around the engine pulley, idler pulleys, and transmission pulley. A diagram is helpful.
• Common gotcha: The belt must be routed inside any belt guides or keepers – if it rides on the edge of a pulley, it will slip or wear quickly.
• No alignment issues reported on these specific JD models, but always check pulley condition (wobble, rust) before installing a new belt.

Should You Buy It

Yes, if you own one of the listed John Deere LX or X300 series tractors and need a reliable, budget-friendly replacement for a worn or broken drive belt. At $15.91 with strong reviews (4.3/5 from 12,782 ratings), it’s a solid value – just double-check your belt length and model compatibility before buying. Not for deck belts or non-JD tractors.