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Can A Threaded Crank Be Adapted To Gt Use?


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#1 motobreeder OFFLINE  

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Posted March 03, 2013 - 07:10 PM

I'm looking at a Briggs motor that has a threaded crankshaft (threaded at the end, but no key way).

 

Anyone have success at adapting this type of motor to use on a garden tractor?

How did you get the shaft to hold the pulley?

 

Thanks,

Dwayne.


Edited by motobreeder, March 03, 2013 - 07:10 PM.


#2 bowtiebutler956 OFFLINE  

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Posted March 03, 2013 - 07:41 PM

 A macine shop could broche the crank for a key. I don't think you'd have much luck getting it to hold a pulley without a keyway.

 

Matt


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#3 olcowhand ONLINE  

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Posted March 03, 2013 - 07:52 PM

This must be a tapered crank?  



#4 Guest_rat88_*

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Posted March 03, 2013 - 08:01 PM

Is it a tapered shaft?

Short of changing the crank or having it machined, the only other fix I have run across, is to gut a golf cart clutch and use the center shaft.

I have not seen a tapered to straight shaft adapter under 1.5" . 

It would depend on what kind of GT you are putting it on. Most of the shaft drive GTs are flywheel side drive and it may be hard to find a PTO clutch with a 1.5 bore. The belt drive versions might be 50/50 depending on the PTO clutch set up.



#5 bowtiebutler956 OFFLINE  

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Posted March 03, 2013 - 09:08 PM

This must be a tapered crank?  

 

It's not necessarily a tapered crank. Here is a pic of one of my Briggs engines with a threaded crank, no keyway.

 

Matt

Attached Thumbnails

  • DSC07195 (800x600).jpg

Edited by bowtiebutler956, March 03, 2013 - 09:09 PM.

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#6 motobreeder OFFLINE  

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Posted March 03, 2013 - 09:24 PM

The shaft is straight (not tapered like a generator).

I was thinking it would work great on a Sears ST/16 which is pulley driven.

 

Sounds like it might be worth going after for flywheel driven GTs.



#7 olcowhand OFFLINE  

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Posted March 03, 2013 - 09:29 PM

If you had a pulley that fit well to the crank, you could put the pulley on the crankshaft, spaced on the backside where it would need to be, then tighten up an appropriate nut against the pulley, then weld the nut to the pulley.  You'd want a higher grade nut, like a grade 8, as the threads will be holding the load.


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#8 IamSherwood ONLINE  

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Posted March 03, 2013 - 10:52 PM

If you had a pulley that fit well to the crank, you could put the pulley on the crankshaft, spaced on the backside where it would need to be, then tighten up an appropriate nut against the pulley, then weld the nut to the pulley.  You'd want a higher grade nut, like a grade 8, as the threads will be holding the load.

 

 

As well as the above, you could drill and tap the pulley hub, and then dimple the shaft. Loctite a

grub screw into that. Heck, do it twice.


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#9 DougT OFFLINE  

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Posted March 04, 2013 - 07:48 AM

If you had a pulley that fit well to the crank, you could put the pulley on the crankshaft, spaced on the backside where it would need to be, then tighten up an appropriate nut against the pulley, then weld the nut to the pulley.  You'd want a higher grade nut, like a grade 8, as the threads will be holding the load.

This would be dependant on the threads. If it was right hand thread, wouldn't it tend to thread the nut off or would you weld the nut to the shaft? I wonder if a taper-lok pulley would grip the shaft tight enough to hold it? Maybe a combination of it and the nut??


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#10 olcowhand ONLINE  

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Posted March 04, 2013 - 09:02 AM

This would be dependant on the threads. If it was right hand thread, wouldn't it tend to thread the nut off or would you weld the nut to the shaft? I wonder if a taper-lok pulley would grip the shaft tight enough to hold it? Maybe a combination of it and the nut??

 

Right hand threads is what you want.  The shaft will be turning CCW, which works to keep the nut tight.  But you are likely right about a taper lock pulley.  I bet it would work, as with belt drive the belt would likely slip before the pulley would.



#11 8tyman8 ONLINE  

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Posted March 04, 2013 - 01:56 PM

Best bet is pull the crank and have a machine shop use a mill and have a new key way cut


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#12 Amigatec OFFLINE  

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Posted March 04, 2013 - 03:24 PM

With no more HP that the motor is putting out I'll bet a taper lock would work.

#13 DougT OFFLINE  

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Posted March 04, 2013 - 09:16 PM

Right hand threads is what you want.  The shaft will be turning CCW, which works to keep the nut tight.  

I guess I was looking at it from the wrong side!           :wallbanging:  



#14 KennyP ONLINE  

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Posted March 05, 2013 - 08:22 AM

I guess I was looking at it from the wrong side!           :wallbanging:  

I do that a lot, Doug!


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#15 whst400 ONLINE  

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Posted March 06, 2013 - 10:14 PM

I would install a set screw through the pulley into a dimple on the shaft AND add two nuts jambed together on the end of the crank for extra hold. Using two nuts jambed together lets you remove them if need be for sevice. They aren't so easily removed if welded on.






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