Black/Silver Can Gearing

[Crafty]

Hey guys, I have never run a black or silver can before. What would be a good starting point for gearing an RC10TC3 with a black can??

[DRCRC]

Here is a great site http://gearchart.com/index.cfm?fuseaction=chart.create

Max FDR for GT2 in TCS is 5.60 with a black can.

TC3 has an internal drive ratio of 2.5

Formula is

(spur/pinion)* IDR = FDR

so

(69T/30T)*2.5 = 5.75 is as close as you will get without going over with the stock pinion. 65T spur with a 29T pinion will give you a 5.60FDR.

I'll email you the PDF of your chart.

Dave

[Crafty]

Thanks Dave!

[rcdave]

Ok for the mathematically challenged 5.6 is the highest you can go.
Does this mean that 5.7 is lower?
I would think that if FDR is like rollout that the higher the number the faster, so why not go 7 to 1 instead of 5.6 to 1.

Good thing I majored in math at university or I would really be confused. Or maybe I am getting old and getting old timers desease (alzheimers).

Please help.

[DRCRC]

First off we can't confuse FDR ( Final Drive Ratio ) with Roll Out.

FDR = spur / pinion * IDR ( internal drive ratio ) ...... IDR is different for each car see your manual for the ratio.

Rollout = Distance the car travels for each motor revolution

Now according to the gearchart.com calculator Rollout = ( Tire Diameter in mm x 3.1416 / FDR )

So based on this formula if FDR increases then Rollout will decrease and your car will be slower.

The example based on my car.

FDR = spur / pinion x 2.255 = 98/45 x 2.25 = 4.91

Rollout = tire diam x pi / FDR = 63mm x 3.1416 / 4.91 = 40.30

if FDR increases

FDR = 98/44 x 2.255 = 5.02

Rollout = 63 x 3.1416 / 5.02 = 39.42


As Spur/pinion ratio increases, Rollout decreases and lower rollout = lower top end speed. In relation to FDR if the spur/pinion ratio increases then the FDR increases and the car will be slower.

Shorter track you want the motor to wind out quicker = lower rollout

Longer track you want the motor to take longer to wind out = higher rollout.

Also Motor RPM and Torque come into play.
The more RPM a motor and less torque = a lower rollout
The less RPM a motor has and more torque = a higher rollout

Here is another calculator you can download http://www.rctek.com/miscellaneous/info_rcgears.html

Hope this helps because I still get it confused sometimes.

Dave

PS...Our track is fairly technical so a lower rollout may help you through the infield.