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Location:
sunny coast, qld
Registered:
October 2002
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formula to work out speed?
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Wed, 21 April 2004 08:17
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i can't work out how to calculate the speed. If you know, tyre radius, diff ratio, rpm, and gearbox ratio, how do you work out the speed?
my tyre circumference is 2.05m, diff ratio is 4.63:1 and I have a A340E auto. Anyone know what the ratio is for that? I just want to know how many revs I am doing at 100km/h as I don't have a tacho at the moment.
thanks
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Location:
Campbelltown, NSW, Austra...
Registered:
January 2004
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Re: formula to work out speed?
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Wed, 21 April 2004 09:05
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In what gear, i think you need the ratio for that aswell
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Location:
sunny coast, qld
Registered:
October 2002
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Re: formula to work out speed?
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Wed, 21 April 2004 12:36
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i will have a look for the gear ratios of the auto. anyone know?
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I supported Toymods
Location:
Perth
Registered:
May 2002
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Re: formula to work out speed?
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Wed, 21 April 2004 12:42
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-2.393 2.804 1.531 1 0.705
reverse 1st 2nd 3rd 4th
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Location:
sunny coast, qld
Registered:
October 2002
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Re: formula to work out speed?
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Wed, 21 April 2004 13:14
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1st 2.804
2nd 1.531
3rd 1.0
4th 0.705
Rev 2.393
bloody hell, you beat me to it! 
so what is the formula then?
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I supported Toymods
Location:
Perth
Registered:
May 2002
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Location:
sunny coast, qld
Registered:
October 2002
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Re: formula to work out speed?
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Wed, 21 April 2004 13:58
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http://www.car-videos.com/tools/speedrpm.asp
this site is much easier to use! looked about 2700rpm like you said JCMF.
I am thinking of going to a 4.2:1 diff which would lower it to about 2300rpm
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