# Right GEARING for racing EV



## Jordysport (Mar 22, 2009)

ksmotorsport said:


> Hi to All! Lets discuss the right gearing for racing EV. For example a Drag racing EV with peak RPM 5500 and dual 9" Netgain motors. Car weight at about 2200 lbs.
> 
> What kind of budget but strong gearbox you sugest?
> For rear end Ford 9" but what size of tire and gear?


Best way and the way i've done it is to make a spreadsheet model on basic principles,

1) Start at the motors (map the motors 1RPM-5500RPM relative to Torque (Nm) 
2) Make another sheet of Velocity 0-X mph, convert to m/s, work back through tyre rolling circumference, "a gear ratio" etc etc 
3) adjust gear ratio according to distance covered (400 odd M is 1/4 mile) 

its a lot to explain but work from basic principles and you will get there .


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## GerhardRP (Nov 17, 2009)

ksmotorsport said:


> Hi to All! Lets discuss the right gearing for racing EV. For example a Drag racing EV with peak RPM 5500 and dual 9" Netgain motors. Car weight at about 2200 lbs.
> 
> What kind of budget but strong gearbox you sugest?
> For rear end Ford 9" but what size of tire and gear?


Really, the question can't be answered without specifying your battery pack. You should probably say what sort of tires and tracks you will be racing on too.
Gerhard


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## ksmotorsport (Nov 3, 2012)

My BattPack is planned to be like in DC Plasma, my tyres will be something like MT Drag 26/8 15"


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## GerhardRP (Nov 17, 2009)

ksmotorsport said:


> My BattPack is planned to be like in DC Plasma, my tyres will be something like MT Drag 26/8 15"


Are those the same tires as you use on the ICE Lada? 
What is your current best 60' time?


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## ksmotorsport (Nov 3, 2012)

Yes, the same tires. Unfortunately We don`t have data ot 60' feet runs. But the time should be not bad.


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## GerhardRP (Nov 17, 2009)

Jordysport said:


> Best way and the way i've done it is to make a spreadsheet model on basic principles,
> 
> 1) Start at the motors (map the motors 1RPM-5500RPM relative to Torque (Nm)
> 2) Make another sheet of Velocity 0-X mph, convert to m/s, work back through tyre rolling circumference, "a gear ratio" etc etc
> ...


BTW, There is a model you might play with to address your question.[I have not tried it, but it looks useful.]
http://www.diyelectriccar.com/forums/showthread.php/yes-another-ev-calculator-45278.html
Gerhard


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## Jordysport (Mar 22, 2009)

GerhardRP said:


> BTW, There is a model you might play with to address your question.[I have not tried it, but it looks useful.]
> http://www.diyelectriccar.com/forums/showthread.php/yes-another-ev-calculator-45278.html
> Gerhard


It does look useful, but the biggest issue i've found with most is the units, all in lbs, but this one isn't by the looks of things. i made my model months ago, and its totally customized to my liking, will give that other one a bash tho, looks a bit cooler than my block of numbers!


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## John Metric (Feb 26, 2009)

ksmotorsport said:


> Hi to All! Lets discuss the right gearing for racing EV. For example a Drag racing EV with peak RPM 5500 and dual 9" Netgain motors. Car weight at about 2200 lbs.
> 
> What kind of budget but strong gearbox you sugest?
> For rear end Ford 9" but what size of tire and gear?


Dual Warp9 motors will make nearly 1500ftlbs torque at 2000amps each. a "gearbox" to handle that better be a racing one, like lenco or B&J.

See my facebook page, Lonestar EV Racing Team, for charts on what two warp9 motors put out as far as torque and horsepower. Then you can back into your gear ratio from your tire size.


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## ksmotorsport (Nov 3, 2012)

Thanks John! I move slowly to EV drag project, and your help is always great!


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