Changing crankset to 3-piece

[Pablo]

I photo-documented the steps of changing over to a 3 piece crank for general usage or for the shifter kit.

First is a picture of wrenched maniac aka lurch or "The Crank".

Then a pic of the dead carcass of a one-piece, or a piece de Ashtabula. Removed from a 1980's Columbia Bike. Note that it is, well, one piece - one forged piece.

Followed by the cleaning up of the bottom bracket to allow the cups to fit. Mostly raised metal, weld seam, paint and crud. Used a moto tool sanding drum. There is no way the cup could be pounded in without the clean-up, but be careful, it still needs to be a press fit. I smacked it with by dead blow hammer, a block of 2-ba-4 and hammer, and a ball peen with a brass drift.

The purchased assembly for under $20.

 

[Pablo]

Continued: Then I did a dry fit.

Took it back apart, greased the bearings with synthetic grease and tackifier.

The final unit, sans cranks. Ready to spin.

 

[Pablo]

Lemme know if you want details....not feeling particularly verbose right now!
It's pretty straight forward, and the kit didn't come with any instructions. The conversion kit is boxed to be sold to the bike mech/shop.

 

[Pablo]

I added some words. Sorry about that.

 

[pi-rat]

cant you make this into a shifter kit by putting a #420 chain sproket on the left side so it will spin te gears on the right? if it works ive got a 21 speed motorbike !!!! i think that i might have to cut off the pedals for it to work though and put a case over it so i dont cut off my leg on the chain and sproket.

 

[Pablo]

No sweat sir.

 

[Nitrohorse]

Pablo,
I'm real new to this motorizing a bike thing, so if I ask a dumb question, please excuse me. I was looking at some bikes at Walmart and Target. There's a crusier that I'd love to buy, but it has the one piece crank and I need the three piece due to my selection of a 4 cycle engine and the larger crank clearance it requires.
How do I know what kit I need to order so that I can use the crank arms that were supplied with the engine?
Thank you in advance,
Larry

 

[Pablo]

I would be reaching.....I think you are best off asking your engine supplier.

But the triple conversion set here: Crankset - 3-piece

 

[Pablo]

Bumped for the folks asking for instructions. We will have steps on our site sometime soon.

 

[SalisCruiser]

cant you make this into a shifter kit by putting a #420 chain sproket on the left side so it will spin te gears on the right? if it works ive got a 21 speed motorbike !!!! i think that i might have to cut off the pedals for it to work though and put a case over it so i dont cut off my leg on the chain and sproket.

would this really work?

 

[Pablo]

Probably not.

 

[DetonatorTuningSolutions]

cant you make this into a shifter kit by putting a #420 chain sproket on the left side so it will spin te gears on the right? if it works ive got a 21 speed motorbike !!!! i think that i might have to cut off the pedals for it to work though and put a case over it so i dont cut off my leg on the chain and sproket.

yep, jack sahft shifter setup with out the jackshaft.

you'll need to asses the power and torque of your engine to calculate the primary reduction needed form the engine output to your lefthand crank sprocket. it also depends on what speeds you want to achieve.

don't forget some sates require the pedals, be sure to check your local laws.

steve