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11/15/2016 7:26 PM
 

     This was my first year to compete in a GreenPowerUSA race. Once we obtained the kit we had three months to build our car. We won seventh place in the race. After the competition we began to research aerodynamics, tires, and sprockets. I have been looking for an axle sprocket for our car idental to the kit issued sprocket except that the one we want needs to be 70 tooth. I have looked long and hard for sprockets like this but have had difficulties. So I was wondering if anyone had ideas on where I could possibly get this type of axel sprocket. Also any additional information on how to improve our car is aprecciated. 

 
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11/16/2016 11:04 AM
 

http://www.globalspec.com/local/214/AL

It's what we in the U.K. Call "bog standard" 3/8 industrial chain. Most big towns will have a chain and bearing supplier. The only possible thing that can go wrong is if the US kits have been supplied with British Standard chain. (GP USA will confirm this) In which case you'd need to swap out both sprockets and chain for ANSI (American Standard) There's a small size difference and the two don't mix. Take your chain along when you go shopping. If the problem is purely with the number of teeth, see if you can get a school friendly engineer with a laser cutter to chop one out for you in stainless. The current world champions use their own laser cut sprockets. There's a good guide to designing a sprocket here: http://www.gizmology.net/sprockets.htm

Good Luck

Edit: It seems I'm right. They are shipped with BS chain sets. You may need to change both or machine your own. Not too hard to do.

 
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12/7/2016 1:26 PM
 

Hello USA, I'm Bob Carter, I've been associated with the Sandbach CAUC team in UK for over a decade. This is my first post on this forum; I'll look in from time to time & if I can offer advice or the benefit of my experience I will :)

FWIW Peter (whs) has been "greenpowering" even longer than I have....

Yes we get all our sprockets laser cut. The results are accurate to about a thou and cheap (little more than the cost of the material) - for example we have a full range of motor sprockets from 14 to 30 teeth (yes, every one!) and that little project cost us less than $50. We use a commercial laser cutting service on the industrial estate where I work and they charge me commercial rates for the jobs. I'm sure every neighbourhood has a similar local facility. I email them a dxf or dwg file of the profile & pick up the results 2 to 4 days later.

FWIW we have standardised on 8mm chain. The 3/8" is similar pitch but much chunkier so the weight of the sprockets & chain is all a little more (the sprockets have to be fatter material). the smaller 6mm chain is no longer roller chain so it's a touch more lossy (we did run with that for a while).

WHen designing a chain transmission remember that sprockets with 12 teeth or less become comparatively inefficient.

cheers

Bob

 
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8/9/2017 11:17 AM
 

Here in the US, your best bet in improving the gearing of the car is to switch over to a standard, versus metric, chain and gear setup. There are many kart suppliers who carry the supplies you need versus having to track down their metric counterparts. 


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