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Old 04-06-2011, 10:44 PM   #1
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Default FDR calculating

Sorry to sound like an idiot and I've seen this posted before but how do you calculate FDR? For ex. 86t spur 16t pinion on a Slash. I feel so embarassed-
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Old 04-06-2011, 11:08 PM   #2
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this should have everything you should need.
http://scriptasylum.com/rc_speed/top_speed.html
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Old 04-07-2011, 07:54 AM   #3
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Thanks for that link; My main concern was heat issues.
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Old 04-07-2011, 08:50 AM   #4
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(Spur / Pinion) x TransmissionRatio

For example, an RC10B4, which has an internal transmission ratio of 2.6, running a 72 tooth spur gear and 27 tooth pinion:

(72 / 27) x 2.6 = 6.93 Final Drive Ratio.

Also check out www.comeseethis.com for gearing help.
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Old 04-07-2011, 11:16 AM   #5
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And here I always thought F.D.R. is Franklin Delano Roosevelt, former president.
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Old 04-07-2011, 11:37 AM   #6
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Quote:
Originally Posted by YoungChazz View Post
And here I always thought F.D.R. is Franklin Delano Roosevelt, former president.
lol! Thanks for those who helped w/formula! Still having heat issues though;gear mesh is ok but 220+ degrees is way too HOT! The power and reaction is awesome though!!
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Old 04-07-2011, 02:02 PM   #7
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What vehicle, motor, pinion and spur are you using?
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Old 04-07-2011, 02:03 PM   #8
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Don't be embarrassed. The only stupid question is the one you don't ask, after all.
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Old 04-07-2011, 02:18 PM   #9
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Quote:
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Don't be embarrassed. The only stupid question is the one you don't ask, after all.
I'm running CC 4600 w Mamba pro, 2s, 16/86. I ran it 21/86 and it was hot as hell. Also ran it 90/16-all w/RRP pinions and TRX spur gears.
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Old 04-07-2011, 02:50 PM   #10
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Here is a small gearing and speed calculator (excel spread sheet) I made some time ago. It is easy to use and modify in accordance with your needs. Also it doesn't require a network connection.

It has a few cars in it already (The Car, Xray 808, Xray T3 and the Mugen MBX6).

I prefer it in stead of the Script Asylum one for the ease of use and its availability

Feel free to use it. I have attached a screen shot and the zipped xls file.
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FDR calculating-rs-gear-speed-calculator.jpg  
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File Type: zip RS gear and speed calculator.xls.zip (3.1 KB, 74 views)
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Last edited by ronsand; 04-09-2011 at 05:28 AM.
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Old 04-07-2011, 03:03 PM   #11
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Good job on the spread sheet and thanks for sharing!
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Old 04-09-2011, 05:12 AM   #12
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you're welcome
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