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  1. #1
    RC poster
    Join Date
    Oct 2019
    Posts
    4

    Why is my motor dithering?

    Howdy yíall. Iíve got an unusual situation. From a full stop, as you slowly input forward throttle, the pinion and spur gears dither about 30 degrees in both directions very rapidly. Itís like the motor canít decide whether to go forward or reverse. It makes a terrible noise while doing so. Itís fine as I input more throttle but Iím concerned that it may damage a component. Especially if I have it tuned down for the grandkids to drive it around the yard at slow speed. By the way, I love that feature!!! Anyway, I removed the motor and tranny. Both are tight and solid. After I put them back in, while adjusting the pinion and spur mesh, I noticed that I could move the gears the same amount back and forth about 30 degrees with my finger. Is it normal to have that much slop in the driveline out to both differentials? Iím wondering if I need to reset the transmitter to factory default and/or recalibrate the ESC. Anyone ever had this happen?

    Any ideas or suggestions would greatly be appreciated.

    PapawFox

  2. #2
    RC Competitor
    Join Date
    Mar 2019
    Location
    VT
    Posts
    88
    Based on what you are initially describing (in the first 6 sentences or so), that sounds like the "usual" sensor-less, brushless motor COGGING. I'm sure that there are hundreds of sites and videos that explain cogging, but if you skip to 4:50 in this video, there is a decent explanation: https://www.youtube.com/watch?v=PVwRI-mSVQ4
    The "solution" to getting rid of the cogging is to get a sensor-ed motor and ESC. Castle Creations would be happy to do so to the tune of $240 (if they had any in stock). There are other providers of sensor-ed motors and ESCs, but Castle is the a popular one (Hobby Wing is another).


    Now, the last part of your post I'm less sure about. 30 degrees seems like too much slop, but I don't have my eRevo here to check.

    --BillJ
    Last edited by Single_Trac; 10-23-2019 at 07:50 AM.

  3. #3
    RC poster
    Join Date
    Oct 2019
    Posts
    4
    Thanks... I’ll check out the video.

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