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Old 04-17-2004, 01:01 PM   #1
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Default Gear ratio/roll out chart...how to calculate?

Hi guys,

I am looking at the setup sheet of my Evolva. Inside there are some gear ratio charts and roll out chart. I don't have a clue as to how these values comes. Can someone supply a formula?
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Old 05-03-2004, 01:49 PM   #2
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it depends on what type of track u run on tight technical track u need accel out of corners fast so u need to run tall spur gears with small pinion gears.with a 3tooth split.i run a g4 eclass.this is how my gear ratio works. for a short i run 20/52 1st gear 2nd gear 24/48 my eng is a rody rbx12. with gear set my car accel like a rocket .now for a big track which is where they run 1/8 scale onroad i run 20/51 1st gear 2nd 24/47. i hope this can at least point u in the right direction . like i said big on spur small on pinion for short tracks.
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Old 05-03-2004, 02:32 PM   #3
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too work out your overall gear ratio you first need to know the cars internal gear ratio, this should be in the manual somewhere, touring cars are usually aroung 2-2.5/1
for example first gear 20/52 2nd 24/48 internal ratio 2.2/1

first gear would be 52 divided by 20 multipied by 2.2=5.72

2nd would be 48 / 24 x 2.2 =4.4

the lower the number the faster the car will go

know you say a rollout chart, in the uk we measure this mm per rev, if this is the same thing this worked out as follows

size of the rear tyre divided by overall gear ratio multipied by pie

first gear with 65mm tyre

65 / 5.72 x 3.142 =35.7mm per rev

2nd

65 / 4.4 x 3.142=46.4mm per rev

mm per rev basically 1 revolution of the engine the car will travel 35.7mm in first gear and 46.4 in 2nd

hope this make sense
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Old 05-04-2004, 01:34 AM   #4
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Dear jas1,

Thanks a bunch for your very informative replies!

One more....How about the calculation of the Front/Rear Overdrive Ratio Table?

Last edited by jasoncsc; 05-04-2004 at 01:56 AM.
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Old 05-04-2004, 02:18 AM   #5
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Exclamation a link for u

here is a link for you.

scroll down a bit u will see the link to the gear software.

i am a noob in gears.... i hope this software can help u a bit.

click me

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Old 05-04-2004, 12:47 PM   #6
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try this link

http://www.rolfje.com/

then click r/c calculator kit
then click the ratio computer
then fill in all boxes and it should work the overdrive ratio for you.
dont know if it works or not
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