i have a dumb question
11-04-2014, 04:56 PM
#27
I make the trailer out of k'nex because they are easy to use and were available. You are correct to assume that my motor is brushless, but my truck does not have enough power to pull the trailer. I loosened the spur gear and did't move, so a tightened it and stripped the gear clean. So their is definitely a problem somewhere. I asked on this website, because I knew someone would be able to help me, although i know pretty much about gearing and motors and what not, i wanted to make sure with the lower turn ration for the different motors. Thanks to posting!!
we are all happy to help....
Like I was saying u need to lower the gearing....or more technically the rollout, the distance it travels with 1 motor rpm.
this can be changed via gearing and wheel size.
By the sounds the GRU is a little expensive so the next option is to use a smaller pinion and/or a larger spur gear.
if u want, let us know what size pinion and spur u are currently running and we can run a few equations to see how much it can be lowered that way.
also..... Can u double check something? With the motor out, is the car easy to push along the floor??? And what about the trailer? Do they both have little rolling resistance?
11-05-2014, 06:32 AM
#28
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Thanks for still being so helpful everyone!!! The gears all are still stock from when i bought it. The pinion gear is a 19 tooth and the spur is a 87 tooth. ECX has came out with a newer Ruckus, I have the older one, so idk if the newer one has different teeth counts. I took off the motor and just rolled in across my carpet floor and it rolled pretty good. The trailer rolled pretty well also. idk how well it should, but i liked how much it rolled.
11-06-2014, 03:07 AM
#29
Ahh sweet, sounds like it's rolling nicely with little resistance....
ok, there is one thing that has been bugging me... FahrtAutoRC touched on it.... Why is it not pulling it?.... Been, brushless u would think it should easily do it. Especially because u are running stock gearing and the rolling resistance is all good. Everything I said about gearing still applies but I think there might be something els limiting the torque.
i think I have a suspicion on what it could be....
by any chance are you still using the stock Dynamite Speedpack™ 2400mAh 7-Cell Ni-MH????!
ok, there is one thing that has been bugging me... FahrtAutoRC touched on it.... Why is it not pulling it?.... Been, brushless u would think it should easily do it. Especially because u are running stock gearing and the rolling resistance is all good. Everything I said about gearing still applies but I think there might be something els limiting the torque.
i think I have a suspicion on what it could be....
by any chance are you still using the stock Dynamite Speedpack™ 2400mAh 7-Cell Ni-MH????!
11-07-2014, 12:24 PM
#36
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i assume you meant 29A. that would be the problem. if you can justify the expense, i would suggest a more powerful brushless system. not only would you be able to pull the trailer with little (or at least less) issue, the vehicle by itself would be way more energetic. going for a 4000kv system like this http://www.hobbypartz.com/car.html wouldnt be any faster than your current system but you'd get up to speed faster, likely with the front wheels in the air.
11-08-2014, 06:16 PM
#37
That doesent sound right?? 29a from a 540 size 4 poll motor....
i would assume the peak current capabilities are 290a. That sounds about right for that size motor
actial currents are a lot different and would require physically measuring
i would assume the peak current capabilities are 290a. That sounds about right for that size motor
actial currents are a lot different and would require physically measuring
11-08-2014, 06:27 PM
#38
Let's look further
so let's assume the motor can handle 290a for short periods on time
the ESC can handle 45 continuos and I'm assuming it can peak to over 190a
the battery can supply 100a continuous and a little more for short periods of time
but I think u would find the actial current draw with out a trailer would be about 70a under acceleration and 35a driving...and with a trailer is would be more.
......
have you tried a smaller pinion yet????
so let's assume the motor can handle 290a for short periods on time
the ESC can handle 45 continuos and I'm assuming it can peak to over 190a
the battery can supply 100a continuous and a little more for short periods of time
but I think u would find the actial current draw with out a trailer would be about 70a under acceleration and 35a driving...and with a trailer is would be more.
......
have you tried a smaller pinion yet????
11-08-2014, 10:16 PM
#40
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11-09-2014, 02:47 AM
#41
Hummmmm I don't know.... 250 watts at 7.4v is 33.78a.... Or 250 watts is only 0.34hp
maybe that's a average power rating, ie. It can handle 250w continuous
And that's nothing speical. Been a 540, 4 poll motor u would think it would be more powerful that a smaller ezrun 380core/540fins 2 poll motor... But as u can see from my old slash video, it appears not.
http://youtu.be/xbQcM_qJ5C4
maybe that's a average power rating, ie. It can handle 250w continuous
And that's nothing speical. Been a 540, 4 poll motor u would think it would be more powerful that a smaller ezrun 380core/540fins 2 poll motor... But as u can see from my old slash video, it appears not.
http://youtu.be/xbQcM_qJ5C4
11-09-2014, 02:56 AM
#42
I think this is either the worlds crappyest 4 poll motor or something els is going on.
if it was me, for starters I would fit a watt meter and see what's going on...
It could be the motor is not powerful enough or it could be the battery is dropping volts under load causing brown out,
both can be reduced with lower gearing.
if it was me, for starters I would fit a watt meter and see what's going on...
It could be the motor is not powerful enough or it could be the battery is dropping volts under load causing brown out,
both can be reduced with lower gearing.
11-09-2014, 02:59 AM
#43
One other thing worth doing would be calculating the Final Drive ratio and comparing it to similar vehicles with the same size wheels. Because I wouldent be supprised if like Traxxas they over gear from the factory
11-09-2014, 04:20 PM
#44
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sorry it has been awhile since I last posted. You guys are getting very involved into this. I have not tried a smaller pinion gear yet, but I want to try it out. The winter season is coming soon, so the truck will not be used for a while so ill not too worried about it. The out put is 290a, with a fully charged battery. I built a smaller (much lighter) trailer and was pulling that around my back yard like nothing, was so happy. But now I need to get better shocks so it doesn't sag as much. I tried the bigger trailer, but did the same thing. I think it is my engineering skills for the trailer, too big ;( Anyway, im thinking about buying a more powerful battery, so that I can use it to pull the heavy load and still have it for speed, what do you think? And do you have suggests for better shocks to keep the car from sagging with the extra weight??
11-09-2014, 04:57 PM
#45
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Yeah, a more powerful battery would be nice. For the shock sagging, get some stiffer springs and top off the shock oil for the back. Keep stock springs on the front; more front traction.
Battery (much more power); http://www.atomikrc.com/collections/...-with-uni-plug
Springs; http://www.amain.com/ECX-RC-Shock-Sp...-Stiff/p177155
Battery (much more power); http://www.atomikrc.com/collections/...-with-uni-plug
Springs; http://www.amain.com/ECX-RC-Shock-Sp...-Stiff/p177155
