1-631645 / 1-633099 PTO Clutch for Exmark Lazer Z | Warner 5218-5
1-631645 / 1-633099 PTO Clutch for Exmark Lazer Z | Warner 5218-5
Overview
This aftermarket 1-631645 / 1-633099 electric PTO clutch is a replacement for select Exmark Lazer Z, Bobcat, Bunton, Husqvarna, Yazoo/Kees, and related commercial mower applications using the Exmark 1-631645, Husqvarna 539102603, Bobcat 2188151, or Warner 5218-5 clutch path.
Common replacement-catalog applications include select early Exmark Lazer Z mowers, Bobcat ZT200 and ZT331 Series, Husqvarna ZTH5223A and ZTH5225A, and several Yazoo/Kees ZKH commercial zero-turn mowers.
The Warner reference path uses a 1-1/8-inch keyed crankshaft bore, approximately 6.31-inch pulley, clockwise rotation, reverse-mount configuration, integral electrical connection, and a 12 VDC clutch-and-brake system.
Important serial-number warning: Exmark used different PTO clutch paths as the Lazer Z platform changed. This page is intended for the earlier 1-631645 / 1-633099 / 103-0664 path. Do not automatically substitute a clutch listed under 103-0665, 1-631732, or Warner 5218-213.
Key Features
- Aftermarket electric PTO clutch assembly
- Primary Exmark Numbers: 1-631645, 1-633099
- Primary Husqvarna Number: 539102603
- Primary Bobcat Number: 2188151
- Warner Cross-Reference: 5218-5, 52185
- Additional Warner Path: 5218-259, 5218259
- Voltage: 12 VDC
- Torque: 175 ft-lbs
- Crankshaft Bore: 1-1/8 inch / 1.125 inch with standard keyway
- Pulley Diameter: approximately 6.31 inch / 6-5/16 inch
- Rotation: CW viewed from pulley side
- Mounting Style: reverse mount
- Connection Type: integral electrical connection
- Belt Groove: A/B combination replacement path
- Common Belt Width: 5/8 inch
- Clutch Type: electric PTO clutch with integrated brake
- Complete assembled aftermarket replacement clutch
Compatible Brands & Model Series
This PTO clutch should be treated as a part-number-first replacement. Confirm the number on the original clutch or the serial-specific mower parts diagram before relying on the mower-family name.
Exmark Lazer Z Applications
- Exmark Lazer Z: select early-production applications using 1-631645, 1-633099, or 103-0664
- Common Replacement-Catalog Serial Path: serial numbers through 159,999
Exmark serial warning: Later Lazer Z machines may use the separate 103-0665 / 1-631732 / Warner 5218-213 clutch path. Match the serial-specific parts diagram rather than assuming every Lazer Z uses the same clutch.
Bobcat, Bob-Cat, Bunton & Ransomes Applications
- Bobcat / Bob-Cat ZT200 Series: select configurations using 2188151
- Bobcat / Bob-Cat ZT331 Series: select configurations using 2188151
- Bunton Commercial Mowers: select applications using 2188151
- Ransomes Commercial Mowers: select applications using 2188151
Bobcat warning: Do not confuse 2188151 with 2721337. Bobcat 2721337 follows the separate Warner 5218-213 replacement path.
Husqvarna ZTH Applications
- Husqvarna ZTH5223A: select 2000–2006 applications using 102603 or 539102603
- Husqvarna ZTH5225A: select 2000–2006 applications using 102603 or 539102603
Confirm the complete Husqvarna product number, engine configuration, original clutch number, connector, and pulley alignment. Husqvarna used several similar-looking commercial PTO clutches.
Yazoo/Kees Applications
- Yazoo/Kees ZKH52220
- Yazoo/Kees ZKH52221
- Yazoo/Kees ZKH52222
- Yazoo/Kees ZKH52223
- Yazoo/Kees ZKH52233
- Yazoo/Kees ZKH52250
- Yazoo/Kees ZKH52251
Use the Yazoo/Kees model list only when the original clutch or parts diagram identifies 102603, 539102603, or another confirmed number in this replacement path.
Additional Part-Number-Based Applications
- Ferris: select commercial mower applications using 1522040
- Woods: select applications using 2188151
- Dixon: select applications using 102603, 109580, 539102603, or 539109580
- AYP-built equipment: select applications using 102603 or 539102603
- Craftsman, Electrolux, Jonsered, Poulan, Roper, and McCulloch: only when the original clutch number matches this path
Replaces OEM Part Numbers
- Exmark: 631645, 633099, 1-631645, 1-633099, 103-0664, E633099
- Toro: 631645, 633099, 1-631645, 1-633099, 103-0664, E633099
- AYP: 102603, 109580, 539102603, 539109580
- Husqvarna: 102603, 109580, 539102603, 539109580
- Yazoo/Kees: 102603, 109580, 539102603, 539109580
- Bobcat / Bob-Cat: 1522040, 2188151
- Bunton: 2188151
- Ransomes: 2188151
- Woods: 2188151
- Ferris: 1522040
Aftermarket Cross-Reference Numbers
- Warner Electric: 5218-5, 52185
- Additional Warner Path: 5218-259, 5218259
- Earlier Warner Number: 5218-70, 521870
- Xtreme: X0015
- Stens: 255-535
- Rotary: 11444
- Oregon: 33-115
- Prime Line: 7-06032
- Additional Aftermarket Reference: 230-4076
Warner-number note: Warner identifies 5218-259 as the replacement for 5218-70. Warner does not state that 5218-259 supersedes 5218-5, although established aftermarket suppliers group 5218-5 and 5218-259 within the same replacement family.
Match the original mower part number first, then confirm the bore, pulley, rotation, mounting orientation, connector, and belt alignment.
Clutch Specifications
- Product Type: electric PTO clutch with integrated brake
- Voltage: 12 VDC
- OEM Warner Reference Torque: 175 ft-lbs
- Crankshaft Bore: 1-1/8 inch / 1.125 inch with standard keyway
- Pulley Diameter: approximately 6.31 inch / 6-5/16 inch
- Rotation: CW according to Warner specifications
- Mounting Style: reverse mount
- Connection Type: integral electrical connection
- Belt Groove: A/B combination path
- Common Belt Width: 5/8 inch
- OEM Warner Current Draw: 5.24 amps
- OEM Warner Coil Resistance: 2.29 ohms
The Warner electrical figures are reference specifications for the original clutch path. Compare the supplied aftermarket clutch with the original before installation.
Important Serial-Number Routing
The early and later Exmark Lazer Z clutch paths are easy to confuse because the clutches share several dimensions.
- Earlier Lazer Z Path: 1-631645, 1-633099, 103-0664, Warner 5218-5
- Common Replacement-Catalog Range: serial numbers through 159,999
- Later Lazer Z Path: 103-0665, 1-631732, 1-641300, Warner 5218-213
- Common Later Range: select serial 160,000-and-higher applications
Do not substitute the early and later clutch paths using only the 1-1/8-inch bore and 6.31-inch pulley measurements. Confirm the original clutch number, connector, mounting orientation, anti-rotation setup, engine configuration, and serial number.
Reverse-Mount & Installation Considerations
Warner classifies the 5218-5 reference clutch as a reverse-mount configuration. Reverse mount describes the clutch’s installation orientation on the engine crankshaft. The center bore remains a conventional keyed 1-1/8-inch bore.
- Document the original clutch orientation before removal.
- Confirm that the replacement pulley sits at the same height as the original.
- Compare the pulley offset with the deck-drive belt path.
- Inspect the crankshaft key and keyway for damage.
- Inspect the anti-rotation bracket for cracks, bending, or enlarged mounting points.
- Do not force an anti-rotation bracket that does not align naturally.
- Confirm that the wiring cannot contact the pulley, belt, exhaust, or rotating engine components.
- Rotate the pulley manually after installation to check for interference.
- Verify belt alignment before engaging the PTO under load.
Incorrect mounting orientation, pulley offset, wiring position, or anti-rotation alignment can cause clutch movement, wiring damage, belt wear, overheating, and premature bearing failure.
Common Symptoms of a Failing PTO Clutch
- Blades will not engage when the PTO switch is activated
- The clutch clicks but the deck belt does not begin turning
- Blades engage when cold but stop after the mower heats up
- The clutch slips during heavy or wet cutting conditions
- The deck belt squeals, smokes, or overheats during engagement
- Burning smell near the engine crankshaft or clutch
- Grinding, rumbling, or excessive pulley-bearing noise
- Intermittent blade engagement under load
- Visible heat damage around the coil or electrical connector
- Excessive looseness or roughness at the pulley bearing
A weak battery, charging-system problem, faulty PTO switch, damaged wiring, poor ground, slipping deck belt, seized spindle, worn idler, or incorrect belt tension can create similar symptoms. Diagnose the complete PTO and deck-drive systems before replacing the clutch.
What’s Included
- 1 complete aftermarket electric PTO clutch assembly
- Electromagnetic coil and integrated brake assembly
- Pulley and center-bearing assembly
- Integral clutch-side electrical connection
Why Buy From PTO Direct USA?
- Part-number-first PTO clutch listings
- Clear physical specifications and cross-reference information
- Separate routing for early and later Exmark Lazer Z clutch paths
- Fitment warnings designed to reduce incorrect clutch orders
- Commercial and residential mower clutch coverage
- Support for mower owners, repair shops, and commercial operators
- Quick-ship fulfillment through trusted distribution partners
Need Help Confirming Fitment?
Send PTO Direct USA the mower brand, complete model number, serial number, deck size, engine manufacturer, engine model, and original clutch number.
Include clear photos of the clutch label, pulley, keyed bore, electrical connector, belt groove, mounting orientation, and anti-rotation bracket. When the original label is unreadable, include measurements for the crankshaft bore, pulley diameter, pulley offset, and clutch-body height.
FAQ
What does this PTO clutch replace?
This clutch replaces select applications using Exmark 1-631645, Exmark 1-633099, Exmark 103-0664, Husqvarna 539102603, Bobcat 2188151, or Warner 5218-5.
What are the main clutch specifications?
The Warner reference path uses a 1-1/8-inch keyed bore, approximately 6.31-inch pulley, CW rotation, reverse mounting, integral electrical connection, 12 VDC coil, and a 175 ft-lb torque rating.
Does this fit Exmark Lazer Z?
It fits select early Exmark Lazer Z applications using 1-631645, 1-633099, or 103-0664. Replacement catalogs commonly associate this path with serial numbers through 159,999. Confirm the original clutch number and serial-specific parts diagram.
Does this replace Exmark 103-0665?
Do not use 103-0665 as the primary fitment match for this page. Exmark 103-0665 is commonly documented on later Lazer Z applications using Warner 5218-213. Marketplace catalogs sometimes combine these paths incorrectly.
Is Exmark 1-631732 the same as 1-631645?
No. Exmark 1-631732 is associated with the later Warner 5218-213 clutch path. Keep it separate from the 1-631645 / Warner 5218-5 path.
Does this replace Bobcat 2188151?
Yes. Warner directly associates 2188151 with the 5218-5 clutch path. Confirm the original clutch label, mower model, and physical specifications.
Is Bobcat 2721337 the same as 2188151?
No. Bobcat 2721337 follows the separate Warner 5218-213 path. Do not substitute 2721337 and 2188151 based on appearance or shared bore and pulley dimensions.
Does this fit Bobcat ZT200 mowers?
It fits select Bobcat, Bob-Cat, Bunton, and Ransomes ZT200 Series applications using 2188151. Confirm the original clutch number and complete mower configuration.
Does this fit Bobcat ZT331 mowers?
It is associated with select ZT331 Series applications using 2188151. Verify the original clutch label and model-specific parts diagram.
Does this fit Husqvarna ZTH5223A?
It fits select 2000–2006 ZTH5223A applications using 102603 or 539102603. Confirm the complete product number, engine, connector, and original clutch.
Does this fit Husqvarna ZTH5225A?
It fits select 2000–2006 ZTH5225A applications using the 539102603 clutch path. Verify the original number before ordering.
Does this fit Yazoo/Kees ZKH models?
It is associated with select ZKH52220, ZKH52221, ZKH52222, ZKH52223, ZKH52233, ZKH52250, and ZKH52251 applications using 102603 or 539102603.
Is Warner 5218-259 the same replacement path?
Established aftermarket catalogs group Warner 5218-259 and 5218-5 within the same replacement family because their major physical and electrical specifications match. Warner officially states that 5218-259 replaces 5218-70, not that it supersedes 5218-5.
Does Warner 5218-259 replace Warner 5218-70?
Yes. Warner identifies 5218-259 as the replacement for the earlier 5218-70 clutch.
Is Xtreme X0015 the same replacement path?
Yes. Xtreme X0015 is an aftermarket replacement path associated with Exmark 1-631645 and 1-633099, Husqvarna 539102603, Bobcat 2188151, and Warner 5218-5.
Is Stens 255-535 the same replacement path?
Yes. Stens 255-535 is commonly cross-referenced to Warner 5218-5 and 5218-259 applications. Match the original clutch number and physical specifications.
What belt size does this clutch use?
This clutch follows an A/B combination pulley path and is commonly used with a 5/8-inch deck belt. Confirm the original belt width and pulley groove.
Does this clutch have a normal crankshaft keyway?
Yes. The clutch uses a conventional 1-1/8-inch keyed crankshaft bore. Confirm the crankshaft key and keyway condition before installation.
Is the mounting hardware included?
Do not assume the crankshaft bolt, washer, key, spacer, wiring adapter, or anti-rotation bracket is included. Reuse or replace the mower-specific hardware as required.
Can I order this clutch by appearance?
No. Match the original part number first, then confirm the 1-1/8-inch keyed bore, pulley diameter, rotation, reverse mounting, connector, belt groove, pulley offset, anti-rotation setup, mower model, and serial number.