Author Topic: Recutting a sprocket ?  (Read 7804 times)

Big Al

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Re: Recutting a sprocket ?
« Reply #15 on: September 15, 2015, 04:41:59 PM »
But how is the original gear held to the assembly? Ideally that wants replacement.

The new outer one can be machine cut to a fit onto the old sprokets, as an inner. Welded in placed. No need to perpetuate a misalignment. However you retain the wrong gearing. 
« Last Edit: September 15, 2015, 11:12:13 PM by Big Al »
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Grommet

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Re: Recutting a sprocket ?
« Reply #16 on: September 15, 2015, 10:38:39 PM »
Hi

What pitch chain is it and how many teeth on the original sprocket?

Sprockets of most sizes are available cheaply and will just need the centre machining then ideally heat treatment. You can probably mount it on the remains of the old one with disc brake bobbins if that's what you are trying to achieve or have it laser welded.

eg http://www.bearingboys.co.uk/?catid=3738&page=2&att1=&att2=&att3=&att4=&att5=

Grommet
« Last Edit: September 15, 2015, 11:01:05 PM by Grommet »

richard

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Re: Recutting a sprocket ?
« Reply #17 on: September 20, 2015, 08:45:07 PM »
The added on extra sprocket is 65 teeth - the original is 60 teeth only . What difference would this make anyone ? And can any change be offset by a change to the engine sprocket.  Cheers
« Last Edit: September 20, 2015, 09:19:47 PM by richard »
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DaveMiller

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Re: Recutting a sprocket ?
« Reply #18 on: September 20, 2015, 09:58:15 PM »
65 teeth on the wheel, rather than 60, will lower the overall gearing to 60/65 of what it was - so same revs at 30 mph as it used to do at 32.5 mph.

Not a huge difference, and would help on hills, but lower top speed and economy.

Gearing would be returned to the original if the drive sprocket on the engine could be increased in similar amount.  So, for example, a 20-tooth sprocket increased to 21 (still slightly lower gearing) or 22 (giving very slightly higher gearing).

Grommet

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Re: Recutting a sprocket ?
« Reply #19 on: September 21, 2015, 07:39:25 PM »
ok so you need a 60 tooth gear

Heres the sort of item  that can easily be found:

http://www.ebay.co.uk/itm/Talon-Kart-Sprockets-NEW-unused-various-TKM-Rotax-Pro-kart-Cadet-60-to-78-/161826360626?var=&hash=item25ad9a4d32

Machine off the old gear leaving a step then machine a step in the new gear and shrink fit it. A few short welds can be used as an alternative or nut and bolt etc..

You havent said what pitch the chain is 3/8", 1/2" etc?

If you dont have access to the machinery required  a local engineering shop should be able to do it for you..

Grommet
« Last Edit: September 21, 2015, 07:43:22 PM by Grommet »

Big Al

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Re: Recutting a sprocket ?
« Reply #20 on: September 22, 2015, 12:55:18 AM »
I agree with grommet. Best method if possible.
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richard

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Re: Recutting a sprocket ?
« Reply #21 on: September 22, 2015, 08:49:21 AM »
Many hanks for the information all - I will forward it all to Dave
outside of a dog a book is mans best friend. Inside of a dog it's too dark to read .Groucho Marx 1895-1977