Repower 520HC with Predator 670 v-twin - PTO Clutch Question

[twin520 2]

I'm in the process of re-powering 520HC with Predator 670 v-twin.
Looking for input regarding what specific electric PTO clutch others have used
and where to get it. I have the crankshaft bushed out to 1 1/8" diameter, 
the tractor drive pulley mounted and up to 2" of free crankshaft and with the 1/4" key-way.
Also note the main load is the 60" mower.
Thanks for your help.
Twin520

[Ed Kennell 46,251]

to the 

 

I have no experience in this conversion, but would think the PTO assembly from the Onan should fit the Predator.

[Achto 31,923]

 

I would think that any electric clutch from a  should work. Most should be set up for 1 1/8 keyed shaft. 

 

Electro 12 for example.

[Bill D 2,894]

I believe the predator has a ball bearing supported crankshaft.   The manual PTO should work. 

[bds1984 1,511]

On 6/16/2026 at 6:37 AM, Bill D said:

I believe the predator has a ball bearing supported crankshaft.   The manual PTO should work. 

 

Single cylinder engines that aren't the 459cc have ball bearings.  I just looked at the parts list for the 670 and saw no ball bearings listed on the parts list.  There is a thrust washer that MAY be able to handle the axial load of a Wheel Horse PTO, but I'd rather just upgrade the 3-amp charging system of the 670 and use an electric clutch.  

[twin520 2]

On 6/16/2026 at 5:15 AM, Ed Kennell said:

to the 

 

I have no experience in this conversion, but would think the PTO assembly from the Onan should fit the Predator.

Ed - Yes I have the original manual PTO setup on with the Predator and working fine. Just concerned about the crankshaft bearings if they can handle the thrust load and the reason to look into an electric clutch. Thanks for your input.

[twin520 2]

Achto, Yes I agree but have not located any part numbers for a Wheel Horse horizontal application just yet. Thanks

[peter lena 9,908]

@twin520  think I would definitely  look into a " soft start "  hook up on that  start , that " 60 "  is like  trying to  drag a  barge ,  incredible drag  , in a sudden violent way  will  quickly  accumulate  other  damage areas . another thing is the condition / maintenance  status  of said deck  , bearing whine  and related belt  bounce , tells you the  story . just what i, have seen , pete  

[twin520 2]

Peter- When say "soft start" hook up are you implying to stay with the manual clutch or is there a "soft start" electric clutch?  Concerning the deck and bearings it is in good shape and have been using it for the last 15 years and have replace bearings as needed. Thanks

[pfrederi 20,692]

There is a "soft Start " item for electric PTOs... I just engage at just above idle and then speed up. It is a bit rough but unless yo are running a commercial mowing business it will probably outlast you.

[peter lena 9,908]

@twin520  replaced bearings ?  thats what you want to do !  keeping up with rotational maintenance ,  think I would try that soft start  set up , sounds like  its already  in a freer / easier  spin up state ,  most of the stuff I see , is long over due , for  maint , staying ahead  of issues is what you want to do  . pete

[kpinnc 18,502]

1 hour ago, twin520 said:

When say "soft start" hook up are you implying to stay with the manual clutch or is there a "soft start" electric clutch? 

 

Soft start clutch controller. Works sort of like antilock brakes. One wire gets wrapped around one of your plug wires that senses the pulses and activates the clutch accordingly. I've used one on my zero turn for over 5 years and it has been great. 

 

A bit pricey, but worth it. 

 

GDI soft start controller.