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  1. #1
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    Sep 2020
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    Pinion gear issue

    Hey guys, so Iím completely new to this forum. I have an XMAXX 8S with the MAX6 ESC and dual castle fans. I absolutely can not keep the pinion on the motor shaft. I have a HR spur and a Traxxas hardened pinion. 54t spur and the 18t pinion. EVERY time I run I spin the pinion EVEN with red lock tight. I wait 4-5 days for dry time. Does ANYONE on here have any insight on what I can do to keep it from spinning off or do I just need to sell it??? Iím not bashing the crap out of it or jumping it. Just driving around the local park. PLEASE HELP ME!!!

  2. #2
    RC Competitor
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    Mar 2020
    Location
    Portland, Oregon
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    87
    Check if the shaft rounded off. it can happen and when it does the pinion always falls off.

  3. #3
    RC Champion
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    Mar 2016
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    1,402
    Try a different set screw
    Flatten the bottom of the set screw
    Keep trying the red loctite- mesh set without the pins
    fabricator

  4. #4
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    Join Date
    Jul 2020
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    17
    I've had my X-Maxx for a little over a month and shredded 4 pinions\spurs before I discovered the cause.....indeed, the pinion was sliding off the motor shaft. When viewed from the side, the flat on the shaft had a visible slope to it, tapering to the end. It was no mystery why the pinion was slipping off. It got worse each successive replacement of the pinion\spur. I couldn't make it through a single pair of batteries before crushing, noisy disappointment. Red loctite was no help.

    To rectify this, I used a Dremel rotary tool and a cutting disk to actually flatten the, well, flat. I then colored the flat with a Sharpie permanent marker, reinstalled the motor, aligned the pinion and spur, and then tightened the grub screw. This will leave a mark on colored portion of the flat when tightened. I pulled the motor, again, and using the same Dremel and a fine-tipped grinding stone, I ground a divot where the grub screw contacts the shaft. This allows the grub screw to screw "in" to the shaft, physically preventing the pinion from sliding off, even when loosened a few degrees.

    Upon reassembly, this solution, combined with only medium-strength blue loctite, has prevented any more shredded pinions and spurs. The only downside I can see is this locks you down to one brand of pinion gears, as the grub screw hole doesn't always seem to be in the same place, longitudinally, across different pinion manufacturers. I've stuck with Traxxas pinions\spurs and I've been fine for the last few weeks over a couple dozen battery runs. The grub screw stays tight, and hasn't moved. I really think the culprit is poor machining of the flat on the motor shaft.

    Now if I can only figure out how to keep the body from popping off.....

    *Traxxas has a strict language policy, please refrain from such language and if the filter replaces words you wrote with "*****" please edit it out. Thanks.*
    Last edited by Double G; 09-02-2020 at 08:12 AM.

  5. #5
    RC Champion
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    Feb 2020
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    As mates says, check out the motor shaft, took out the pin system.

  6. #6
    RC Champion
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    Feb 2020
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    Quote Originally Posted by MikeBusch2 View Post
    I've had my X-Maxx for a little over a month and shredded 4 pinions\spurs before I discovered the cause.....indeed, the pinion was sliding off the motor shaft. When viewed from the side, the flat on the shaft had a visible slope to it, tapering to the end. It was no mystery why the pinion was slipping off. It got worse each successive replacement of the pinion\spur. I couldn't make it through a single pair of batteries before crushing, noisy disappointment. Red loctite was no help.

    To rectify this, I used a Dremel rotary tool and a cutting disk to actually flatten the, well, flat. I then colored the flat with a Sharpie permanent marker, reinstalled the motor, aligned the pinion and spur, and then tightened the grub screw. This will leave a mark on colored portion of the flat when tightened. I pulled the motor, again, and using the same Dremel and a fine-tipped grinding stone, I ground a divot where the grub screw contacts the shaft. This allows the grub screw to screw "in" to the shaft, physically preventing the pinion from sliding off, even when loosened a few degrees.

    Upon reassembly, this solution, combined with only medium-strength blue loctite, has prevented any more shredded pinions and spurs. The only downside I can see is this locks you down to one brand of pinion gears, as the grub screw hole doesn't always seem to be in the same place, longitudinally, across different pinion manufacturers. I've stuck with Traxxas pinions\spurs and I've been fine for the last few weeks over a couple dozen battery runs. The grub screw stays tight, and hasn't moved. I really think the culprit is poor machining of the flat on the motor shaft.

    Now if I can only figure out how to keep the body from popping off.....
    The mate Acidic01 has a thread with a possible solution to this issue.

    https://forums.traxxas.com/showthrea...opping-off-fix
    Last edited by Double G; 09-02-2020 at 07:12 AM.

  7. #7
    RC poster
    Join Date
    Jul 2020
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    Quote Originally Posted by Juanmacine View Post
    The mate Acidic01 has a thread with a possible solution to this issue.

    https://forums.traxxas.com/showthrea...opping-off-fix
    I did all that, and even added a length of nylon rod between the hooks that slip under the shock towers, thinking it would help prevent the body from compressing, lengthwise. It really hasn't helped. Even stranger, it pops off on slow rolls and impacts far more often.

  8. #8
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    Sep 2020
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    I will have to try that. Thanks guys for the replies!!!!

  9. #9
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    Quote Originally Posted by hunter080108 View Post
    I will have to try that. Thanks guys for the replies!!!!
    You're welcome.

  10. #10
    RC Champion
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    Quote Originally Posted by MikeBusch2 View Post
    I did all that, and even added a length of nylon rod between the hooks that slip under the shock towers, thinking it would help prevent the body from compressing, lengthwise. It really hasn't helped. Even stranger, it pops off on slow rolls and impacts far more often.
    It's very strange.

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