A Newbie Question About Crank Shaft And Driver Clutch

[OneTimeUser]

All,

By the time I get my driven clutch and drive pulley lined up there is not a whole lot of keyway engaged between the two. The frame came with a 6.5 hp motor and my new, larger, engine makes for a tight fit.

If I was a good welder (which I am not) I would extend the 1 inch crank shaft about 2 inches to provide more actual engagement of the key between the crankshaft and the driver clutch.

I've looked around for a crankshaft "extension that would provide for more key way connection between the crankshaft and the driven clutch. I had in mind some sort of bolt on extension that would allow for more and longer contact.

Can't find it. It would need to have female threads on both ends to permit it to screw onto the crankshaft and then allow the driven clutch to screw on to the crank shaft extension.

I fear that the minimal key way engagement I currently have will lead to a poor and perhaps wobbly fit.

My engine is a Predator 420 and my driven clutch is a Blast LED Series 40.

Thanks in advance.

BTW, I've got the Murray Kilowatt ready to roll--minus a few little items like brakes. Couldn't have done it without y'alls help.

 

[Hellion]

Got pics of the dilemma?

 

[OneTimeUser]

Helloion,

Unfortunately a picture won't help. Problem is that by the time I slide the driven clutch out far enough to align properly there is very little keyway engagement. A crankshaft extension is the only solution I can think of. So far, I'm unable to find such a thing. I suppose I could take the crank out and take it to a machine shop to fabricate a screw or weld on extension.

I'm sure I'm not the only one to have this situation, and I was hoping for a screw on solution.

Oh well, guess I'll just run it and see what happens...

 

[Sparkwizard]

Mount the driver on the crank. It does engage the key, correct?
Rather than modify the crank, modify your jackshaft. They can be purchased in different lengths. If that doesn't work for your situation, move the jackshaft to where it does work. Yes, pictures would help.

 

[Hellion]

Only thing I can think of:

Crankshaft adapters for useless tapered 4-strokes

Interesting post over there on the Rear Engine Karts Forum, it’s a year old (Nov 2024) but the ebay search link still works. That’s a lot of product and honestly something I’d never have considered using, always thinking a tapered crank engine was a lost cause. All my engine finds have been so...

www.diygokarts.com

 

[OneTimeUser]

Thanks for the help. I cannot move my jackshaft. As it is I have only 1/4 inch between it ant the frame. My cart has the engine as sprung weight, not on a swing arm, so the close tolerance is ok. However, when I line up the series 40 driven clutch properly there is about 1 1/2 inch of clutch that is "hanging out" past the crankshaft. I can't do this situation proper with pictures.