Good rule of thumb?

[thzero]

Ran across this elsewhere; by overgear I'm assuming that it means too high of gear ratio, undergear means too low of gear ratio. That sound right?

Hot motor, cool controller, cool batteries = undergeared
Cool motor, hot controller, hot batteries = overgeared
Warm motor, warm controller, warm batteries = happy components

Reason I ask is that I had overgeared my XXX-T slightly when switching to brushless and the motor was getting hot. So the solution was to lower the gear ratio by going to a smaller pinion. So this seems a bit backwards, or I have my under/over definition wrong.

[SunnyHouTX]

Yeah, the definitions are a little mixed up there.

[suicideneil]

As a rule of thumb those guidelines are correct, but there are always exceptions top the rule:-

way over geared - hot everything
motor too small/ underpowered = will run hot regardless of gearing

etc etc. What motor & kv & voltage were you using?...

[thzero]

Mmms. Ok. Well, as far as the XXXT, its a 5700/MM running 30C 4000-4200MaH batteries 2S batteries (from variety of sources). I honestly don't remember what the original gear ratio was that I missed, but basically I scratched it went and figured out the overall ratio for the Firestorm Flux and then used the same overall ratio for the XXXT which resulted in a lower gear ratio. That dropped the temps on the motor to the acceptable range.

Originally Posted by suicideneil

As a rule of thumb those guidelines are correct, but there are always exceptions top the rule:-

way over geared - hot everything
motor too small/ underpowered = will run hot regardless of gearing

etc etc. What motor & kv & voltage were you using?...

[thzero]

Well I finally got batteries and all together and took the RC8T out for a run.

MMM/2200 using 50/16 gearing and 5S 5800MaH (Zippys). Motor was up to around 140 after some long high speed passes. Batteries were around 90. But the MMM fan came on.

Thoughts?

Originally Posted by suicideneil

As a rule of thumb those guidelines are correct, but there are always exceptions top the rule:-

way over geared - hot everything
motor too small/ underpowered = will run hot regardless of gearing

etc etc. What motor & kv & voltage were you using?...

[suicideneil]

Doesnt sound too bad- what speed is that geared for with your setup exactly ( I would pump the numbers into the calc but Im lazy :P )?

Doing speed runs will heat things up a bit more vs normal bashing argueably, so I wouldnt be too concerned- just allow the motor and esc to cool down every now & then between runs, then bash/ speed run some more. :)

[thzero]

52.62mph is what BG's says. I was going with it because people were mentioned it was a good combo.

Was gonna try going down to 50/14 which is a "46.05".

I will say though, belting the tires (I did the insides with gorilla tape and outsides with 50lb test fishing line) means very minimal if any ballooning!

Originally Posted by suicideneil

Doesnt sound too bad- what speed is that geared for with your setup exactly ( I would pump the numbers into the calc but Im lazy :P )?

Doing speed runs will heat things up a bit more vs normal bashing argueably, so I wouldnt be too concerned- just allow the motor and esc to cool down every now & then between runs, then bash/ speed run some more. :)