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  1. #1
    RC poster
    Join Date
    Sep 2017

    Slash 4x4 Excessive Cogging?

    I'm having a problem with my slash 4x4: there is excessive cogging at low speeds, much more than what I would expect. The esc and motor heat up very quickly if I'm doing any kind of starting/stopping. The car was purchased brand new two months ago and never overheated or otherwise abused(at least I think so).

    I've had a rustler for years, so I know brushless motors aren't good for low-end, but I like to drive slow and it's kinda discouraging for my slash to be undrivable below maybe 10 mph so. It isn't slow enough for me to even walk next to it, even after I geared it down.

    The motor cogs so badly that sometimes I have to get up to 50-70% throttle before the car will really accelerate... and even then it sits there for a second and you can hear the motor being tortured before it finally builds up the rpm to move the car. I've checked for binding in the driveshaft, and I've checked the pinion to make sure it's placed correctly. The mesh should be okay, I used the paper method because you can't see the side profile like a 2wd car.

    The only way I have found to fix this is by unplugging the battery and recalibrating the esc, but in a few minutes the problem comes back. Now, I've never owned the 4 pole version of the velineon motor, but I've looked at the shaft of both my 2-pole and 4-pole motors, and the shaft of the 2 pole spins freely, while the 4-pole is difficult to turn, and certainly won't spin. Is this normal?

    There are several things that I think may be causing this:

    -4x4 and weight may lead to more cogging(gearing down didn't help my problem though)
    -4-pole system cogs more?
    -bad esc or motor
    -some sort of driveline failure I'm unaware of.

    The truck runs normally if I keep the speed up, and I've no reason to suspect internal damage. The only thing that could have damaged the drivetrain was when a rock got stuck in between the motor and driveshaft and ruined it, but it's been replaced. After stripping the spur gear with my off-brand 11t pinion, I installed the center diff, which I think should be fine. Tt doesn't feel any different anyways.

    I'm posting this to see if any of you guys can give me some insight. The truck has always cogged way worse than either of my rustlers, even straight out of the box. From what I've seen on youtube, I don't think this is normal.

    As an afterthought, the cogging seems to lessen when I use my Onyx 35c battery instead of the Traxxas 25c's. I know 25c is really low, so maybe the battery just isn't up for the job, although I thought Traxxas's batteries were at least okay for 1/10 scale... Maybe I'm wrong.

    Thanks for any help, it's appreciated
    Last edited by Erkorei; 11-17-2017 at 11:34 PM.

  2. #2
    RC Turnbuckle Jr.
    Join Date
    Feb 2002
    center diffs usually eat up power, I wouldn't run it.... is the battery a 2s or 3s? 4 pole motors are way different than 2 pole motors, and out of the vehicle are quite notchy to turn by hand

    are you sure you are in the proper mode, lipo or nimh?

    what gearing?

  3. #3
    RC Champion shack351's Avatar
    Join Date
    Dec 2016
    I just back-spaced my post... what Jimbo said.


  4. #4
    RC poster
    Join Date
    Sep 2017
    So I put the stock pinion back in, and I think that was it, which is funny because that was part of the reason I geared it down to 11/54. Maybe it was just never calibrated right before I put the new pinion in. I thought 32p would work with 0.8 metric so I have no idea why the new pinion doesn't work. I also bought a new spur gear and took out the center diff, if that means anything.

    It is in lipo mode, that's the first thing I did when I got the car. Running on 3s battery. The light is green like it should be. After I charge my batteries I'll take it out for a run and see if the cogging comes back, but it's running fine now so I think I just have to stick with the stock 13/54 gearing.

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