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Old 07-15-2010, 08:06 AM   #1
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Default 1/12th Gearing with 1S LiPo - what spur and pinion?

Just getting back into 1/12th scale pan racing after being out for 5+ years.

Need a little help with gearing.

Would you please post what you're running, specifically the following info:

Battery: 1S LiPo, 5000mAh
Motor: 17.5T Novak SS Pro
ESC: Havoc 1S
Tire Diameter: 1.8"
Track Size: 30 x 65

I've downloaded the rollout formulas and have the rollout numbers for the ESC/Motor for 1/12th applications. This does provide me with the mathematical calculation of the spur/pinion choices.

I am just looking for "actual" spur and pinion sizes that you racers are using at the track. Haven't made my investment in pinions and spurs and would like to keep the amount I need to a minimum.

Also, I am running an AE 12R5.1. Concerning spur gear size: it comes with a 96T spur gear. Of the few gear ratios I have found searching the web, none use this spur gear. Is it because the required pinion would be too large? Preventing the motor from being able to be mounted to get a proper gear mesh? Another reason?

Again, just trying to learn from what others have already gone through/done without having to buy an excessive number of gears to experiment with.

Thanks. Jim
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Old 07-15-2010, 08:29 AM   #2
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Look for low 70 spurs and upper 30 pinions. Lots of nice product out there like PRS and Kimbrough.
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Old 07-15-2010, 12:04 PM   #3
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I am running on a bit bigger of a surface 80-90ft x 30ft carpet. You may need to drop a couple of teeth from where I start out.

Motor Timing:
Try it initially with the motor in the factory position (or how you got it). If you need more torque to get off the corner turn the timing ring fully right looking at it from where the sensor wire plugs in. If you run out of pinion teeth you can turn the timing ring to the left slowly until half way any more and you run out of torque and just build heat in the motor.

Starting Rollout : 98mm

using 64 pitch gears:
Spur : 72 or 74
Pinion : 50 (Range: 47-57)
Tire : 46mm or 1.8"

The gear ratio looks completely ridicules at first.

check your motor temp should be between 90-110deg. If you are getting it hotter then something bad is happening.

On my surface I have found running the tires at 41mm front and 43mm rear will produce quicker laptimes and stop the tires from pealing off the rims as much.

Single cell cars are lighter and by using a non-boosted esc that even reduces your tire wear further.

Last edited by Capt'N_Slow; 07-15-2010 at 12:17 PM.
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