917-05121 PTO Clutch for Cub Cadet MTD 717-05121 717-04376 917-04376, for Cub Cadet RZT-42 RZT-S42 Troy-Bilt Colt XP Mustang Colt RZT 42" White Outdoor 42" ZT-4200 ZT-42 Replace 717-04376A 917-04376A

What It Is

This is an electric PTO (power take-off) clutch that engages and disengages the mower blades on select Cub Cadet, Troy-Bilt, and White Outdoor zero-turn mowers with 42-inch decks. It replaces OEM part numbers 717-04376, 917-04376, 717-04376A, and 917-04376A.

Fitment & Compatibility

• Check your OEM number first: This clutch fits models that originally used 717-04376, 917-04376, 717-04376A, or 917-04376A. It also cross-references to 717-05121 and 917-05121.
• Deck size: Designed for 42-inch decks only. Will not fit 46-inch or 50-inch decks without modification.
• Common compatible mowers: Cub Cadet RZT-42, RZT-S42, Troy-Bilt Colt XP, Mustang Colt, White Outdoor ZT-4200, ZT-42. Also fits some MTD-built 42-inch zero-turns.
• Measurements: Verify the clutch hub diameter (typically 1-inch), bolt pattern (3-bolt, 4.5-inch center-to-center), and overall thickness (approx. 2.5 inches) against your old unit. Slight variations exist between OEM and aftermarket versions.
• Wiring: 2-wire connector. Confirm your mower’s harness matches the blade-type terminals (usually 12V DC).

Key Things to Know

• Quality vs OEM: This is an aftermarket replacement. Build quality is generally good, but some users report slightly noisier operation or shorter lifespan than OEM Cub Cadet clutches.
• Installation difficulty: Moderate. Requires basic tools (socket set, multimeter, possibly a puller). You’ll need to remove the deck or access the clutch from under the mower. Disconnect battery first.
• Common gotcha: The air gap between the clutch rotor and armature must be set to 0.010–0.015 inches. If the gap is too wide, the clutch won’t engage; too tight, and it drags. Check the included shims.
• Warranty: Typically 1 year. Keep your receipt and test the clutch immediately after install—some units arrive DOA due to shipping damage.

Should You Buy It

If you need a budget-friendly replacement for a worn-out PTO clutch on a 42-inch Cub Cadet or Troy-Bilt zero-turn, this is a solid choice. It’s not as durable as OEM, but at roughly half the price, it’s worth it for DIY repairs on older or secondary mowers. Skip it if you demand OEM fit/finish or run a commercial operation.