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Author Topic: Rear Axle gearing  (Read 826 times)

sylvaman

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Rear Axle gearing
« on: 24 October 2020, 09:11:30 pm »
Can i ask what is the popular sprocket size on the axle,  if using the 40 pitch (420) chain and , 10 tooth Tav 2 Torque Converter.

Is it still 60 as originally recommended, or in practice , have different sizes been tried / used ?

Appreciate it is track dependent , but talking about Stretton.

Thanks and Have a great event on Tues 27th. 

Chris L

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StefanN

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Re: Rear Axle gearing
« Reply #1 on: 24 October 2020, 11:37:20 pm »
I’m using 70 - so 7:1

ChrisS

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Re: Rear Axle gearing
« Reply #2 on: 25 October 2020, 05:04:00 pm »
I think 6:1 is too high, my system is direct drive (no TAV), so slightly different, but I tend to run closer to 9:1 at stretton. Especially if we are using the 'Carousel' circuit.

sylvaman

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Re: Rear Axle gearing
« Reply #3 on: 25 October 2020, 07:20:39 pm »
Thank you Stefan, Chris.  :)  Interesting..... seems like i may need to get a sprocket with more teeth.

 Would i have been on the carousel circuit when i came up on the 15th July , earlier this year ?

StefanN

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Re: Rear Axle gearing
« Reply #4 on: 25 October 2020, 08:18:13 pm »
Just to clarify,  my 7:1 ratio is multiplied by the TAV auto range of 0.9-2.7:1
giving 6.3-18.9:1

ChrisS

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Re: Rear Axle gearing
« Reply #5 on: 26 October 2020, 06:58:12 am »
Yes, we were on it in July, it includes the really tight hairpin in the middle, it seems to be the one they use most.

sylvaman

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Re: Rear Axle gearing
« Reply #6 on: 26 October 2020, 04:39:20 pm »
Thanks Chris .

Does that mean you are using 219 standard kart Chains and Sprockets in aluminium and of which there is much more choice and availability ?

Stefan.   Do you mind me asking where you get your larger (420) sprockets from and are they still made of steel as mine is ?

StefanN

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Re: Rear Axle gearing
« Reply #7 on: 26 October 2020, 08:51:00 pm »
My sprocket came from Gemini Karts and yes its steel.

sylvaman

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Re: Rear Axle gearing
« Reply #8 on: 26 October 2020, 10:17:03 pm »
Thanks Stefan.  Did you try other sprockets before arriving at 70 or jump straight from 60 to 70. 

If so have you lost out on much top end , but gained low down torque and acceleration.

Have a great day tomorrow.

StefanN

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Re: Rear Axle gearing
« Reply #9 on: 27 October 2020, 05:45:58 am »
I started at that ratio based on others experience.   Probably because the track we use mostly is not about straight line speed, I’ve not run out of top end speed.   I’ve removed the governor in my engine, but I doubt I often get anyway near the governor limit and suspect I am way off peak torque or power.   I don’t have space to put a larger sprocket in with a lot of chopping about, otherwise I would.    The 70 tooth is huge so packaging becomes a challenge.  I’ve not looked into a smaller chain that would give you smaller sprockets.

ChrisS

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Re: Rear Axle gearing
« Reply #10 on: 28 October 2020, 09:00:04 am »
I'm running a 420 chain and sprockets in steel, but, as I am not using a TAV, I have the Honda 2:1 reduction box so my rear sprocket can be smaller. I use a 53T from Gemini.

My drive sprockets are swappable and yesterday @ Stretton in the wet I was using 11T which gave me a final ratio of 9.6 : 1. 

dunworkin

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Re: Rear Axle gearing
« Reply #11 on: 29 January 2021, 08:14:32 pm »
Just been perusing eBay for an engine and found a Lochin with 6:1 reduction gearbox. Ive not made up my mind between a centrifugal clutch or CVT. Collective knowledge please for making an informed decision. Ciao fellas

StefanN

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Re: Rear Axle gearing
« Reply #12 on: 29 January 2021, 11:01:51 pm »
Either. As examples, Chris’ ERA at 9.6:1 fixed and my Bugatti at 6.3-18.9:1 TAV both work.    There’s a bit less complexity and opportunity for stuff to break with a fixed ratio.

A lighter cyclekart helps if you go fixed ratio, but is a good idea anyway.


jim

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Re: Rear Axle gearing
« Reply #13 on: 30 January 2021, 09:42:13 am »
I use a centrifugal clutch and 12:1 gearing. The Engine governor removed and it hits max revs at stretton.

dunworkin

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Re: Rear Axle gearing
« Reply #14 on: 30 January 2021, 11:40:29 am »
Was just wondering if a clutch would work if its already running at 1/6 engine speed  :-\ can you get different springs for them to tune the engagement point ?