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Old Mar 24, 2013, 10:18 PM
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United States, IN, Scottsburg
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Help!
stutter, and loss of power

Hello, I'm not really sure if this is the place to post this, but i am new to this site and am in need of a little help.
I got into rc's about a year ago, and I (dry wallet) bought a hsp brontosaurus rtr 1/10th pro, or himoto, or exceed, or many other dif brands all rolled into one P.I.T.A. rc. So far I have upgraded my drive shaft, wheel hexs, wheel/tires, and radio/receiver. A few weeks ago I was getting a stutter when I would pull back full throttle on my radio. (fully charged battery, and brand new batteries in my radio).
I decided to do some research on it, and found something called a "Brown out".
So instead of buying the glitch buster, I bought a brand new FS-GT3B radio and receiver combo. This changed nothing. I also read something on "cogging", so I bought a 21t steel pinion (as my brass one had no teeth, and 64t steel spur gear (as my plastic one had no teeth either). This also has changed nothing. I am at a loss here, and am ready to throw this thing in the trash. My friend told me to buy a whole new truck and start from scratch. I can't do that nor do I intend to. SO any help as to what is going on would def. be appreciated.
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Old Mar 25, 2013, 01:56 AM
Did you check the FAQ already?
SoloProFan's Avatar
The Netherlands
Joined Jul 2010
12,754 Posts
You say both the spur gear and pinion gear stripped teeth? Sounds like the transmission is jamming or at least not running smoothly. With no pinion on the motor and moving the car by hand, does it appear to run smooth?

Also, it could be your car battery, while being full, has lost it's ability to sustain high current under load, so when you go to full throttle, the voltage collapses and the glitching starts. You can't see on the outside if a battery has lost it's power, voltage is no indication, it can still give good voltage, as long as you don't draw much current from it.
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Old Mar 25, 2013, 03:26 PM
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If it's stuttering under load, it's not a brown out. If it was a brown out you would lose total control (steering as well) until enough power returned. The transmitter/receiver wouldn't be the cause of a brownout, it would be the BEC (which is part of the ESC). A "glitch buster" is a capacitor that keeps some current available under heavy load so the receiver doesn't lose power (brown out).

Cogging is a much more likely culprit if it's a brushless motor. To see if it's cogging, get the truck rolling a bit and give it medium throttle input, then stop it and give it very little throttle, then stop and give it a ton of throttle. If it stutters and makes noise all the time, it's not likely not cogging. Are you still running it with the stock battery pack? Do you have any other packs you can try using to see if the pack just can't deliver enough current?

By the sounds of the gears, that's where I would start. Does the truck roll smoothly with no power on? If there's some binding in the drivetrain it could explain the stripped gears and binding will increase load/current draw as well.
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Old Mar 26, 2013, 12:48 AM
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Rolling with no power, there isn't any grinding noise other than the gears meshing. and as far as the pin/spur gear stripping, they were the older gears before I replaced them with steel gears. the pin. was brass, and the spur was plastic. if I barely pull the throttle it sits there and freaks out.. (like a twitching/uhhh shudder, lol)
However if I give it med. throttle, same thing then it finally goes, and full throttle, same thing then finally goes. Here's the catch, if I lift it off the ground e.i. no contact punch the throttle it takes right off, no hesitation with wheels flying freely. and yes it's the oem (sorry mechanic) battery pack (7.2v 2000mah nimh). I have a lipo 2cell, but nothing to charge it with as my quick charger took a dump. As far as the pinion gear it was brass and I've heard a lot of swag on brass pin. gears going out after such period of time, decided to upgrade. So taken from you two have told me, maybe it's time to try a new battery pack.
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Old Mar 26, 2013, 01:28 PM
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The pack might be partially at fault, but it sounds like it's just a cheap ESC struggling with cogging.

Is the pinion/spur you upgraded to the same number of teeth as stock?
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Old Mar 26, 2013, 11:29 PM
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no, the pin. is 21t (brass was 17t) , but the spur has the same teeth.
Unfortunately I can't buy/find a steel 17t pin. gear =(
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Old Mar 27, 2013, 09:30 AM
Did you check the FAQ already?
SoloProFan's Avatar
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Jumping from 17 to 21 is quite a big step. What module does the gear use? 48 dp, 0.6, something else? Maybe we can find a compatible pinion before you smoke your motor/ESC.
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Old Mar 28, 2013, 11:57 PM
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woah woah, I'm a noob at this. What module does the gear use? what does that even mean?
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Old Mar 29, 2013, 06:35 AM
Did you check the FAQ already?
SoloProFan's Avatar
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Joined Jul 2010
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Module defines the shape of the teeth. Commonly used modules in rc are 0.6, 1.0, 48dp. Mixing gears that are different module, even when looking quite similar, will give a less than smooth running transmission.

Some interesting reading: http://en.wikipedia.org/wiki/Gear
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Last edited by SoloProFan; Mar 29, 2013 at 06:42 AM.
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