UDC Parts Spindle Assembly for Cub Cadet 54-inch Deck — OEM-fit Replacement Kit with Hardware

UDC Parts 918-06978 is a direct-fit spindle assembly engineered to replace worn or damaged spindles on 54-inch Cub Cadet and compatible MTD/Troy-Bilt/Columbia decks for reliable cutting performance.

If your mower deck is producing uneven cuts, loud bearing noise, or excessive vibration, worn spindle assemblies are a common culprit. This UDC Parts replacement spindle matches the OEM dimensions and mounting pattern (replaces MTD 618-06978, 918-06978) to restore deck stability and blade alignment without the need for aftermarket modifications.

How does this spindle restore mower deck performance?

Replacing a failing spindle removes play between the blade and deck and eliminates bearing noise, which helps blades track true and cut more evenly. The assembly includes the main spindle housing, pulley-ready top, and all mounting hardware you need for a complete swap.

• Full kit: 1 spindle, 4 mounting bolts, blade mounting bolt, pulley lock nut, washer.
• OEM match: Designed to replace MTD 618-06978 and 918-06978 for a bolt-on fit.
• Precision fit: 6-point star flange and factory-style dimensions for alignment.

Will this fit my Cub Cadet or other mower models?

The spindle is built to the same specs used on many 54-inch decks from Cub Cadet and related brands. Verify compatibility by checking your original part number or matching the mounting hole pattern and overall dimensions before ordering.

• Cub Cadet models include RZT-L54, RZT-S54, RZT-LX 54, XT1-GT54, XT2-GX54 and variants with KH/KW designations.
• MTD/Craftsman models supported: T8400, G8600, G8400, Z6900, Z6600.
• Also fits Troy-Bilt, Columbia, and several Mustang and Bronco series lawn/zero-turn tractors listed in specifications.

What are the key dimensions and hardware in the package?

This assembly follows the original envelope so it installs without deck modification. Critical measurements are provided so you can confirm fitment against your current spindle or service manual.

• Overall height: 6-13/16" (173 mm) for proper blade clearance and belt alignment.
• Pulley outer diameter: 5-9/16" to match belt and pulley spacing on 54" decks.
• Includes mounting and blade hardware: 4 mounting bolts, a blade bolt, pulley lock nut, and washer for a complete installation.

How long should a replacement spindle last and what maintenance helps extend service life?

Service life depends on use, conditions, and maintenance, but installing a quality spindle and following simple upkeep increases longevity. Keep decks free of debris and check pulleys and belts regularly to reduce stress on bearings and housings.

• Inspect pulleys and belts for wear; replace worn items to avoid premature spindle failure.
• Keep deck undersides clean to prevent debris intrusion into bearings and seals.
• Torque mounting and blade bolts to factory specs to prevent loosening and vibration.

Who is this for: This UDC Parts spindle assembly is intended for homeowners, landscapers, and repair shops servicing 54-inch Cub Cadet and compatible MTD/Troy-Bilt/Columbia lawn tractors and zero-turn mowers. If you are replacing a spindle that matches the listed OEM numbers or the given dimensions and model families, this kit gives you the mounting hardware and pulley compatibility needed for a straightforward, reliable repair.