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  1. #1
    RC Enthusiast
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    3906 E-Maxx metal idler gears

    Does anyone know where I can get a set of metal idler gears for my 3906 E-maxx?

  2. #2
    RC Champion
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    Quote Originally Posted by flowingby
    Does anyone know where I can get a set of metal idler gears for my 3906 E-maxx?

    CLICK HERE Unlimited Engineering, now the only place you can find them in stock.
    You see that you can get a single for running in one speed or two for both hi and low.
    15" WB HCR Mutant-Maxx Castle UE FLM 3906

  3. #3
    RC Competitor
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    Kcaz- I went to the traxxas site and looked at the exploded views of the 3906 and the 3905 transmissions and I saw that the idler gear for both models were the same model number. So if thats the case why will the one here not work??
    E-Maxx stock
    Stuck in the middle of nowhere Iraq

  4. #4
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    TRA3996X will work , BUT it is only a direct fit for the 2nd gear slot in the transmission case of a 3906 . If you want to replace the first gear idler it has to be cut equally on both side (because of the bearings) . I measured it using the stock plastic idler . Once you take the trans apart you will see what I'm talking about .
    ERBE - 8ight T/E - Kyosho Inferno

  5. #5
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    The part numbers are not the same, the 3906 part # is 3996 and the 3905 part # is 3996X, 3996X is wider. They are not compatible right out of the package, but you can use them if you do a little bit of grinding. I used them in my 3906s after grinding them down to the same dimensions as the stock ones.

    Edit: Dang, I type slow.

  6. #6
    RC Champion
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    ^ and ^ I learned something today. There you have your answer. I just want to throw something out: most find that with BL 1st gear is very hard to utilize in a 3906.
    15" WB HCR Mutant-Maxx Castle UE FLM 3906

  7. #7
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    I rarely even use first gear in either my brushed or brushless 3906s. The rare times that I do use it is if I am crawling around on some rocks or something.

  8. #8
    RC Turnbuckle Jr.
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    I would convert your 2 speed tranny to a single like everyone else is saying. I did the GorillaMax conversion and have not looked back.
    Last edited by mkrusedc; 07-20-2009 at 10:19 PM.
    E-Maxx Neu1515 1y/MGM 5s

  9. #9
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    I've thought about that a few times, maybe after my checking account has a chance to recoup, I'm in the middle of purchasing everything I need to go lipo, so maybe I will make that my next project.

  10. #10
    RC Competitor
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    ok so i just buy one of them tra3996 metal gears and split the tranny case and drop it in for second gear replacement? and i can remove the idler gear from 1st gear?
    E-Maxx stock
    Stuck in the middle of nowhere Iraq

  11. #11
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    YES . that is the easiest most inexpensive way to do it , the tra3996 metal idler is a direct drop in , leave the first gear side plastic . but if you choose to make the 1st gear metal it has to be cut dow to the exact same dimensions as a plastic tra3996
    ERBE - 8ight T/E - Kyosho Inferno

  12. #12
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    I took everyone's advice and successfully installed two metal idler gears. I did of course have to file down the front of the gear box. I also sanded down the gearbox halves (where the idler gears guide shafts mount). After a thorough cleaning & lubricating the gears the transmission worked like a champ. I wish there were 31-T and 36-T output gears to completely eliminate the plastic gears.

  13. #13
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    Those are vrey hard to find but it exist Ultramaxxed GEN III gear set!


    I hope you did that mod before you re-instal the trans.


    Fred
    3906 CC 1717 / MMM GA 7075 UE Khead LST2 DIFF

  14. #14
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    Wow, that is nice! I didn't use an Allen wrench but I did use an off brand steel pin on a repaired input shaft & sealed it up with tire glue. When the new one comes in I'll definitely try the mod. Thanks!

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