Spindle Assembly 121-5681 / 116-5712 with Pulley for Exmark Quest

Overview

This aftermarket 121-5681 / 116-5712 spindle assembly is a replacement-style mower deck spindle assembly for select Exmark Quest and Toro Titan mower deck applications.

This listing is organized around the 121-5681 / 116-5712 spindle path. Optional package choices may include the matching 139-2433 / 110-6864 spindle pulley depending on the selected option. Match your original spindle number and pulley number before ordering.

Key Features

• Aftermarket replacement-style mower deck spindle assembly
• Product Type: Spindle Assembly
• Lead Part Numbers: 121-5681, 116-5712
• Also Replaces: 109-6394, 109-8744, 116-3497, 116-5138
• Optional Pulley Path: 139-2433 / 110-6864 / 125-5574
• Common Deck References: 42 inch, 48 inch, and 52 inch deck paths appear across this spindle family
• Optional package variants may include spindle pulley components
• Organized by spindle and pulley part number first to reduce fitment confusion

Compatible Brands & Model Series

This 121-5681 / 116-5712 spindle assembly is used on select Exmark Quest and Toro Titan mower deck applications.

Common model-series references include:

• Exmark Quest 42-inch deck references, including QST20BE422
• Exmark Quest 48-inch deck references, including QST22BE482 and QST23KC482
• Exmark Quest 52-inch deck references, including QST23KC522 and QST24BE522
• Toro Titan Z4800 and Z5200 deck references
• Toro Titan model references including 74812, 74813, 74814, 74815, 74816, and 74818 where the original spindle number matches the listed path

Verify your part numbers before ordering.

Replaces OEM Part Numbers

• Exmark / Toro Spindle Assembly Numbers: 121-5681, 116-5712, 109-6394, 109-8744, 116-3497, 116-5138
• Alternate No-Dash References: 1215681, 1165712, 1096394, 1098744, 1163497, 1165138

Optional Package Part Number Breakdown

Part numbers below may apply to available package options. Not every package includes every component listed. Select the option that matches the parts needed for your repair.

• Spindle / Mandrel Numbers: 121-5681, 116-5712, 109-6394, 109-8744, 116-3497, 116-5138
• Related Cutter Housing Kit References: 116-4386, 109-5242, 109-9380, 116-3491
• Spindle Pulley Numbers: 139-2433, 110-6864, 125-5574
• Alternate Pulley References: 1392433, 1106864, 1255574

Spindle Specifications

• Spindle Part Number: 121-5681
• Also Replaces: 116-5712, 109-6394, 109-8744, 116-3497, 116-5138
• Height Reference: 6.3 inches
• Blade Mounting Pattern: Round
• Grease Fitting: No
• Hardware Note: Mounting hardware may be included with some spindle-only versions, but confirm by selected option image before checkout
• Application Note: Confirm spindle housing style, shaft setup, blade mounting pattern, pulley setup, and belt routing before ordering

Common Symptoms / When to Replace

• Mower deck spindle is noisy, loose, seized, or wobbling
• Blade has excessive play at the spindle shaft
• Deck vibration increases during blade engagement
• Spindle pulley is worn, damaged, bent, or no longer tracking the belt correctly
• Original spindle number matches one of the listed Exmark / Toro replacement numbers

Quick Ship Fulfillment

This item may ship directly from one of our trusted U.S. distribution partners to help reduce transit time. Packaging, labeling, or warehouse origin may vary, but the part will match the replacement numbers, fitment notes, and specifications shown in this listing.

Why Buy From PTO Direct USA

• Fitment-first product organization by spindle part-number path
• Clear spindle, pulley, and related housing-kit references for package variants
• U.S.-focused fulfillment options for faster delivery when available

Need a Custom Package?

Need a different combination of parts? Email us the part type and part numbers you need, such as spindle assemblies, blades, belts, pulleys, reinforcement rings, bearings, or hardware. We can review the part-number path and quote a custom package when available.

FAQ

Is this an OEM Exmark or Toro spindle assembly?

No. This is an aftermarket replacement-style spindle assembly intended to replace the listed Exmark / Toro part-number path when the physical fitment details match.

What are the lead part numbers for this listing?

The lead spindle numbers are 121-5681 and 116-5712. This listing also references 109-6394, 109-8744, 116-3497, and 116-5138 in the same replacement path.

Are 139-2433, 110-6864, and 125-5574 spindle numbers?

No. Those are spindle pulley numbers and should stay in the pulley bucket.

Are 109-5242 and 116-4386 part of the same listing?

They are related Exmark Quest cutter housing kit references, but they should be kept separate from the main 121-5681 / 116-5712 spindle path unless the selected option or parts diagram confirms that version.

Does this listing include the pulley?

Only the selected spindle-with-pulley option includes the pulley. Review the selected variant title and product image before checkout.

Can I order by deck size only?

No. Deck size alone is not enough. Match the original spindle number first, then confirm mower model, deck layout, pulley number, blade mounting pattern, mounting hardware, and belt routing before ordering.