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Old 12-05-2010, 07:14 PM   #1
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Default 1/10 Onroad gear/motor tuning

I know Ive posted a thread like this, but it always seems to go off topic.

So what I am asking is how/what do you do with gearing on a track?
If the motor is running too hot and you've tried what you can with your speedy/motor, you go smaller pinion or larger spur.
So what you are really trying to do is make as much RPM as you can without sacrificing too much speed, and this does what? Less current going through the motor sections causing it to build up heat as it runs through those certain sections for too long - if you know what Im trying to say there.
Also, if you look at a motor (the insides) how do you know if anything has melted? I looked at my Tekin Redline 21.5 and the metal ring where it looks like it was 3 pieces soldered together to make one solid ring, should those soldered looking sections be flat with the metal pieces? Mine looks fairly flat on the outside, but the inner side looks as if it is sticking further inside than it probably should.
I hope this will teach me how to gear the car for particular tracks.
1 more thing, with the Tekin RS, or any other programmable speedy, I find Im spending alot of time with the throttle above 80%, if not 100% running on Turbo. If i go slowly below WOT, the car is really slow and when you go full throttle, then it picks up 70% of its speed. Is this normal?

Thanks guys.
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Old 12-05-2010, 08:29 PM   #2
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Only have acouple of your answers.


By putting a smaller pinion gear on the car, you are reducing the mechanical torque load that is being applied to the motor. Because the torque load has been reduced, you allow the motor to spin faster at a given total torque for the car, which increases the motors MMF (Reverse Voltage) to the ESC, which reduces the current being drawn from your battery. (Less current, less heat). For Brushless system, its pretty much the same, instead of MMF you have a slip angle between the rotor and poles. The larger the angle the more power the motor will create, but it also increases the heat. You can reduce the slip angle, two ways. Reduce your timing on the motor, or you can gear it lower to reduce the mechanical torque load. Both will cause a decrease in heat.

As for your speedo settings. If you need more speed at less throttle, try adding more end bell timing to your motor, and decrease your turbo/boost timing. You might also want to try lowering your start RPM, as this will allow more timing in with lower RPM.

Cheers,
Shawn.
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Old 12-05-2010, 09:44 PM   #3
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I think some modern motors suffer from overrevving too, and often you need to watch that especially on wide open tracks where a short ratio and long times spent at WOT (i.e. turbo on) might get you in trouble.

I think the best way to find a good gearing and speedy setup is to spend a little bit of time on track with a data logger and read what the motor is doing. That's what I do anyway. This is of course if you don't have any source of local advice to help you with a starting point for your tuning.
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Last edited by niznai; 12-05-2010 at 10:20 PM.
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Old 12-05-2010, 11:40 PM   #4
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Thanks shawn, I guess Id have to reduce the boost timing and add some timing on the motor itself, AND try a higher FDR (greater number).

That should give me better mid throttle speed/power with around the same top-end minus some speed.
All I have to do is get some spurs and pinions and try which combination gives me good all round performance with low temps. Once I have that down, then tweak the speedy for that extra edge
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Old 12-06-2010, 03:31 AM   #5
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Is there a link/post where it explains how to set the gearing/ESC for tracks, just like there are posts on how to break-in nitro engines? I don't remember ever seeing one.
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Old 12-06-2010, 03:44 AM   #6
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Quote:
Originally Posted by DJ_Shakespear View Post
Is there a link/post where it explains how to set the gearing/ESC for tracks, just like there are posts on how to break-in nitro engines? I don't remember ever seeing one.
Well, the good news is that electric motors don't need to be broken in...

The bad news is that there is no such thing as a reliable gearing recommendation any more.

All the motors are different. All the ESCs are different. And the ESCs have so many settings that you can make a motor run in a completely different way just with a couple of presses of a button.

Best advice is to find the thread for your particular ESC, have a read, and go to the manufacturers website to seek out a safe starting point for the ESC settings. Choose either the manufacturers own motor or one that is known to run well with the ESC.

If you go extreme with gearing, extreme with ESC settings or extreme with motor settings, you're going to have problems!
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Old 12-06-2010, 04:40 AM   #7
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I didnt mean a post LIKE how to break-in nitro engines, just something along those lines, but for gear tuning and what you should generally look for, just like nitro tuning - too lean and your looking at overheating and parts problems.
Is it possible to have too high an FDR and over heat the motor? Not an insanely high FDR, but pretty much way too high? Or would the temps stay relatively consistent once you reach the sweet spot, using the same ESC settings?
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Old 12-06-2010, 10:52 AM   #8
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Quote:
Originally Posted by DJ_Shakespear View Post
I didnt mean a post LIKE how to break-in nitro engines, just something along those lines, but for gear tuning and what you should generally look for, just like nitro tuning - too lean and your looking at overheating and parts problems.
Is it possible to have too high an FDR and over heat the motor? Not an insanely high FDR, but pretty much way too high? Or would the temps stay relatively consistent once you reach the sweet spot, using the same ESC settings?
Gearing and timing is a very individual thing. I ran my 1/12 on saturday, that i thought was fast, until i increased my rollout by 2mm, and the motor came to life. Some motors have a real sweet spot for gearing, alittle to high or low, and it doesnt perform as well.

If you dont know where to start, take the manufactors recommendations (Or as someone at an RC Club), and run it hard for 2-3 minutes, then check your temps, if they are good, run for another minute or so, Check Again. Right up till the end of your race. If your bashing, then make sure it runs cool until your battery is done (carefull when running lipo for bashing).

Once you figure out your baseline you can experiment with increasing timing, and changing the gearing. The secret is to make one change at a time, and monitor your progress with the motor temps, the feel of the car, and the lap times if your racing.


Shawn.
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Old 12-06-2010, 05:17 PM   #9
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I only use it for racing, and that would be a bit hard since 21.5 is replacing 17.5 I believe. I still have to test it out on that track and see how it performs and what temps I get. Otherwise, the last meet I went to, it went well and only once it just got to 99 degrees! After that I managed 75-85 degrees Celsius but I could still feel the power drop with about 2 mins to go, so I believe all I had to do was go larger spur/smaller pinion - I went from 41/100 to 36/100, and it felt alot better. I ended up placing 3rd at the end of the day, so Im happy with that being only my second race meet with 21.5 electrics
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