tompat3463
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| posted on 8/3/13 at 07:03 PM |
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Chain drive diff question / ratios !!
building a fireblade engined mini. Using the old subframes as there in great shape and the engine is going in the front with an extended front end.
the thing I cant get my head around it the drive ratio I need. im mechanicly mninded but final drive ratios and whats needed for the weight of the car
is above me 
so. I have got the cbr893 engine running a turbo at the minute and runniing maybe £170hp but im gunna put it back to standard before fitting it in the
mini so that im not dealing with too much at a time.
the standard engine I think produces 125bhp so my question is what number teeth sprocket and drive gire should I be looking for ?
im not wanting to achive massive high speeds my indy blade topped out at 110 and I was happy with that because it used to get U there so quickly.
also while on the subject..once to take the crown wheel off a diff it effectively has no ratio until u put the sprocket on ?? am I right ??
thanks in advance people 
[Edited on 8/3/13 by tompat3463]
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ReMan
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| posted on 8/3/13 at 09:18 PM |
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once to take the crown wheel off a diff it effectively has no ratio until u put the sprocket on ?? am I right ??
Yes. :-)
The ratio will be that of gearbox to sprocket as on a bike
www.plusnine.co.uk
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minitici
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| posted on 9/3/13 at 09:16 AM |
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Here is a link to a sprocket ratio calculator (.xls) for the CBR 893
Calculator (.xls)
Another useful calculator can be found on Gearing Commander
Biggest problem with fitting a bike engine into the front of the Mini is getting enough space for a suitable sized differential sprocket.
Large sprockets could foul with the rear of the subframe or the steering rack.
Usually a 41 tooth sprocket is about as big as you could go (I normally recommend a 39 tooth)
In any case you are going to be running a very short chain which can effect chain life.
To get a sensible final drive ratio you will probably need to fit a smaller gearbox sprocket.
I'm not sure if 530/13 or 14 tooth sprockets are available - maybe Andy Bates knows?)
Again - the smaller front sprockets combined with a short chain run could mean a short chain life.
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40inches
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| posted on 9/3/13 at 10:15 AM |
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This forum may have the answer. Bike engined mini
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tompat3463
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| posted on 9/3/13 at 09:43 PM |
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Thanks for the replies guys. So e useful information. Would anyone happen to know diameters for sprockets ? May be helpful for working out my max size
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I'm using an extened front end so I wanna cram as much in as possible
Tia Alan
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minitici
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| posted on 13/3/13 at 11:29 AM |
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quote:
Originally posted by tompat3463
Thanks for the replies guys. So e useful information. Would anyone happen to know diameters for sprockets ? May be helpful for working out my max size
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I'm using an extened front end so I wanna cram as much in as possible
Tia Alan
Here is a link to a sprocket diameter calculator (.xls)
Sprocket Diameter Calculator
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