Lawn Mower Spindle Assembly with Bearings Compatible with Bobcat 4171231 Mower Spindle Assy Replaces 4115850, 4165023

What It Is

This is a complete lawn mower spindle assembly with pre-installed bearings, designed to mount and spin the cutting blade on zero-turn and riding mowers. It replaces OEM Bobcat part 4171231 and cross-references 4115850 and 4165023, making it a direct drop-in for compatible decks.

Fitment & Compatibility

Before buying, check three things:

1. Deck type and size: This spindle fits Bobcat zero-turn mowers with 48", 54", and 61" fabricated decks, typically from 2010–2020 models. Confirm your deck uses a 5/8" hex shaft (common for these spindles) and that the mounting hole pattern matches (usually 3-bolt, 3.5" center-to-center).

2. OEM versus aftermarket: This is a non-OEM replacement. While it claims to match Bobcat 4171231, some aftermarket spindles have slightly different bearing preload or housing thickness. Measure your old spindle’s overall height (typically ~4.5") and shaft length before ordering.

3. Blade bolt size: This spindle uses a 5/8"-24 UNF blade bolt (not included). Verify your existing blade bolt threads match, or order one separately.

Key Things to Know

• Quality concerns: At $60.75, this is a budget option. Some users report shorter bearing life (1–2 seasons) compared to OEM Bobcat spindles that can last 3–5 seasons. Inspect bearings for smooth rotation before installation.
• Installation difficulty: Moderate. Requires removing the deck, unbolting the old spindle (often seized), and torquing the new one to 40–50 ft-lbs. Have a penetrating oil and impact wrench ready.
• Common gotcha: The spindle housing may be slightly taller or shorter than OEM. If your blade hits the deck or sits too low, you’ll need to adjust deck leveling or return the part.
• Warranty: Most sellers offer a 30-day return window but no long-term warranty. Test fit immediately.

Should You Buy It

Buy this if you need a quick, low-cost fix for a Bobcat zero-turn mower and are comfortable with a 1–2 season lifespan. Skip it if you mow commercially or want OEM durability—invest in the genuine Bobcat spindle (typically $100–$130) for longer service.