Installing your new PTO Clutch doesn’t have to be complicated, but it does have to be done right.
A clutch that’s even slightly misaligned or under-torqued can overheat, slip, or fail long before its time.

Whether you’re replacing a Warner, Ogura, or installing an Ox Clutch replacement for your John Deere, Husqvarna, Cub Cadet, or Exmark, this step-by-step guide walks you through how to install your new PTO clutch the right way.

Start by removing the old clutch and preparing the engine shaft for your new one.

1. Take a photo of how the old clutch was installed. You’ll use it for reference during reassembly.
2. Remove the failed clutch from the crankshaft and note if there were any spacers between the clutch and engine block. Keep them, you may need them again.
3. Clean the crankshaft thoroughly with fine sandpaper or emery cloth to remove corrosion, rust, or debris.
4. Inspect the shaft and keyway for wear or damage. Any burrs or scoring can prevent proper mounting.

A clean, smooth shaft ensures that your new clutch seats properly and runs true.

Preparation 2: Wiring Inspection

Before you mount the clutch, check the electrical system that powers it.

• Battery voltage should read 13–14.2 volts DC while the engine is running.
• Follow the wiring harness from the clutch back to the battery and inspect:
• Safety switches
• Connectors
• Fuses
• Wires for chafing or corrosion
• Tighten all loose connectors and clean dirty contacts.

If your PTO clutch doesn’t receive full voltage, it won’t fully engage.. and that’s a common cause of clutch failure.

Preparation 3: Determine Clutch Orientation and Crankshaft Length

Your new clutch will install differently depending on which direction it faces and how long your engine’s crankshaft is.

1. Identify your setup:
• Pulley toward the engine → CW
• Magnet toward the engine → CCW
2. Place the new clutch on the shaft in the same orientation as the original, and make sure any saved spacers are reused if required.
3. Check pulley alignment. The clutch pulley must line up perfectly with the mower deck pulley.

Now, look through the clutch’s outer bearing:

• If the crankshaft extends ¼ inch or more into the bearing, you have a long crankshaft.
• If the crankshaft does not reach the bearing, it’s a short crankshaft.

This difference determines whether you’ll use a flat washer (long crankshaft) or a D spacer (short crankshaft).

Brake Inspection

If your clutch includes a brake assembly, confirm that the armature sits directly beneath the brake tab before bolting it up.
Improper brake alignment can prevent full disengagement and cause drag and will destroy your clutch.

Installation: Short Crankshaft

For short crankshafts, a D spacer supports the clutch bearing.

1. Confirm an air gap between the crankshaft end and the tip of the D spacer. There must be space. If there’s no gap, the clutch won’t clamp correctly and will fail.
2. Install the D spacer and align the clutch with the anti-rotation bracket.
3. Insert a clean, Grade 8 bolt through the spacer and into the crankshaft.
4. Torque values:
• 3/8" bolt: 40–45 ft-lbs
• 7/16" bolt: 50–55 ft-lbs
5. The bolt must thread at least ¾ inch into the crankshaft.

Installation: Long Crankshaft

For long crankshafts, use a flat washer instead of a D spacer.

1. Confirm that the crankshaft penetrates the outer bearing but does not touch the flat washer - a slight gap is necessary.
2. Align the clutch with the anti-rotation bracket.
3. Install the Grade 8 bolt through the washer and into the crankshaft.
4. Torque values:
• 3/8" bolt: 40–45 ft-lbs
• 7/16" bolt: 50–55 ft-lbs
5. The bolt should engage ¾ inch into the shaft, minimum.

A properly torqued retaining bolt keeps the clutch and bearing secure during operation.

Wiring Your New PTO Clutch

Your equipment may use either a one-wire or two-wire connection system. Match your wiring to one of the following setups:

Two-Wire Connection (Matching Plugs)

If the clutch and equipment connectors match, simply plug them together. Installation is complete.

Two-Wire Connection (Non-Matching Plugs)

If the plugs don’t match:

• Cut the connectors off both.
• Splice the wires directly together using heat-shrink connectors.
• Polarity doesn’t matter: The two wires are interchangeable.

One-Wire Connection

If your old clutch had a single wire:

1. Ground one wire from the new clutch to a bare metal surface on the engine or frame (not painted).
2. Splice the other wire into your equipment’s single power wire.
   A solid, low-resistance ground is essential. A poor ground will prevent the clutch from engaging or cause overheating.

Burnishing (Final Step)

Once the clutch is mounted and wired, you’ll complete the burnishing process. This vital step is a controlled break-in that seats the clutch’s friction surfaces and ensures full torque.

1. Start the engine and set throttle to half speed.
2. With the mower stationary, engage the PTO clutch until blades reach full speed.
3. Disengage and wait for the blades to stop.
4. Repeat this cycle 10 times total.
5. Shut off the engine and re-torque the crankshaft bolt to the same values listed earlier.

This process burnishes the clutch plates and sets the bolt clamping force correctly.
For a detailed explanation, see our companion post:
How to Burnish a PTO Clutch (and Why It Matters)

Congratulations! Installation is Complete!

Once burnished and re-torqued, your clutch is ready for service. Reinstall your belts per your mower’s manual, and check that pulleys, wiring, and brackets are all secure.

Your new Ox Clutch is now properly installed and ready for reliable operation season after season.

Keep Your Equipment Running Strong

At Ox Clutch, every replacement PTO clutch we sell is built for lasting performance, backed by our one-year warranty, and supported by our exclusive Lifetime Discount Program.

That means you can shop with confidence knowing that even years down the road, we’ll have your back with affordable replacement options and expert support.

Explore our full selection of replacement PTO clutches for John Deere, Husqvarna, Cub Cadet, Exmark, Warner, and more - and see why so many homeowners, landscapers, and repair shops trust Ox Clutch to keep their equipment running strong. And if you have any questions, we are here to help.

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