UDC Parts 618-3129 Spindle Assembly / 44 48 50 54 60 inch Decks/Replacement for MTD Cub Cadet 918-3129C 918-04394 918-04426 618-04394 618-04426

What It Is

This spindle assembly is the rotating hub that drives your mower blades. Designed for mid-to-large residential and commercial Cub Cadet and MTD zero-turn and lawn tractor decks (44 to 60 inches), it replaces a failed or worn spindle to restore clean, vibration-free cutting.

Fitment & Compatibility

Before buying, verify three things:

• Deck size: Fits 44", 48", 50", 54", and 60" decks. Measure your deck width or check the model number.
• OEM cross-references: Replaces MTD/Cub Cadet part numbers 918-3129C, 918-04394, 918-04426, 618-04394, and 618-04426. If your spindle has a different OEM number, measure shaft diameter (typically 5/8" or 3/4") and bolt pattern (usually 3-bolt, 2.75" spacing).
• Brand compatibility: Designed for Cub Cadet and MTD (including Troy-Bilt, Yard Machines, Yard-Man, Craftsman) with stamped steel or fabricated decks. Not for older or non-MTD platforms like John Deere or Husqvarna.

Quick check: Remove a blade and measure the spindle shaft diameter and the bolt circle. If they match 5/8" shaft and 3-bolt 2.75" spacing, this is likely correct.

Key Things to Know

• Quality: Aftermarket part, but rated 4.6/5 from 222 reviews. Users report it’s as durable as OEM at half the price. Includes pre-installed bearings and grease fittings.
• Installation difficulty: Moderate. You’ll need a socket set, torque wrench, and possibly a puller to remove the old spindle. Expect 30–60 minutes per spindle.
• Common gotchas: The bolts included may be slightly shorter than OEM; reuse your original bolts if they’re in good shape. Also, check that the pulley fits your belt width (typically 1/2" or 5/8") before final assembly.
• Grease fitting: A zerk fitting is pre-installed—grease it after installation and periodically to extend bearing life.

Should You Buy It

If you have a 44–60" MTD/Cub Cadet deck with a worn or wobbly spindle, this is a solid, budget-friendly replacement. It’s not OEM, but the high rating and included grease fitting make it a reliable choice for DIY repairs. Avoid if you need exact OEM packaging or have a non-MTD deck.