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Blinky Timing & Gearing

After some discussion, about blinky gearing and timing, with a few good minds I thought I should share at least part of these discussions on...

After some discussion, about blinky gearing and timing, with a few good minds I thought I should share at least part of these discussions on here.  This comes from a few of us testing a number of motors but recently all testing the same motor.  That is the excellent Team Wave Eclipse.  The things we noted were very different settings in gearing and timing producing very similar results, even in feel.  Those were 6.7 FDR with 30 timing (max) and 4.0 FDR with 0 timing (stock).



So the situation is 17.5T brushless motor hooked up to an ESC in blinky mode.  We can change the can timing and the gearing only and we're racing on club sized, carpet, tracks.  Here's the basics of gearing and timing and the way I look at them:

Increase timing = more bottom end (min rpm), more top end (max rpm), slower acceleration from bottom to top (less torque)

Decrease timing = less bottom end (min rpm), less top end (max rpm), faster acceleration from bottom to top (more torque)

Increase gearing (lower FDR) = more bottom end, more top end, slower acceleration

Decrease gearing (higher FDR) = less bottom end, less top end, faster acceleration

Now the thing I should probably note here is how I consider top end, bottom end and torque separately.  Often torque is thought of as bottom end but I don't feel this is the case.  From my experience adding timing actually makes the motor more punchy out of the corner but takes longer to reach top speed, hence why I consider them separately.

Now if you've got keen eyes you might notice from the basic rules I have written above that increasing/decreasing the timing has the same effect as increasing/decreasing the gearing and I think this key to this discussion.

From the discussions I've been having the one phrase that has stuck with me the most is that 'You can't beat physics' or rather the first law of thermodynamics.  This basically means you can never get more out than you put into any system.  So we all have batteries that give and equivalent Voltage and can cope with current demands well beyond 17.5T blinky, we all have rotors and stators of similar performance.  And we all have the same choices of timing and gearing but no matter what you do with your timing and gearing you simply cannot make your motor 'faster' than another.  The only way to do that would involve adding something extra into the system such as a higher Voltage or a stronger rotor magnet.

So I think the conclusion of these interesting discussions should be that with gearing and timing you can tune the feel and power delivery of the motor (ie how much power you have at which part of the throttle), which might help get a quicker lap time, but you can never make it out and out faster.  What you gain in one area you will lose in another.

Now what this means at the track is that you don't have to max your motor timing, you can run with zero timing for a nice smooth feel.  Generally I find more timing makes a more aggressive feel.  Efficiency is also king.  Each motor will have a sweet spot for both gearing and timing, move away from this sweet spot and you lose revs and torque and only gain heat.  Your motor will always be fastest at it's most efficient but that might not always suit the track.  Since motor manufacturers want you to have a good experience with their products it would not be surprising if they came set from factory with the most efficient timing setting.

So my suggestion is when trying a new motor don't add any timing, just gear it for the straight and check it out.  Then try some timing and lower gearing for a more aggressive feel, if that's what you feel you need.  Don't set gearing and timing to reach a certain temperature on the motor.  If the motor is on the pace and running cool there is little sense in making it less efficient to warm it up a bit.

Well there you have my theory to setting up blinky motors.  I'm sure it's not the only theory out there and I'm sure there will be those who disagree with it.  So feel free to leave me a comment below and share your own theories on blinky motor set up.
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  1. As an engineer I am having a problem with how you are getting more bottom end and more top end at the same time. If you gear numerically higher you should get more rear wheel torque but less wheel rpm which would mean lower top speed?

    ReplyDelete
  2. What about if i have a second hand motor where i don't know is it set to the sweet spot. Can i still use the 6Amp drain set up as a guide?

    ReplyDelete
    Replies
    1. It is a good starting point, you have to check your temperatures etc with a few short runs. I have tuned friends motors to 5-6Amps to start with, including second hand ones.

      Obviously you need to use the analyser to check it is all ok.

      Delete
  3. Can you tell me how your tune the motor to 6a. Is it a case on changing the timing until you get it close or is there another way? Apologies for the novice question?

    ReplyDelete
    Replies
    1. Yep, you just need to adjust the endbell, and check it on your motor analyser. Although remember the 6a is just a general guideline, all motors are slightly different. Although I would not aim any higher than that.

      http://www.thercracer.com/2016/07/g-force-brushless-motor-analyzer-review.html

      Delete

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