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  1. #1
    RC poster
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    Mar 2019
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    25 yr old Maxx Transmission problem

    converted a 25 yr old Maxx truck to electric
    beast in forward
    my son 25 years ago must have disconnected the reverse and servo (doesn't remember)
    only found 2 servos hooked up (Steering & Throttle/Brake)
    transmission explosion part # 4989 is the reverse linkage ?
    I have no brakes or reverse
    using a JR Racing controller
    JR RS300 receiver 3 channel
    i converted a XXX NT Sport truck no problems
    also rebuilt 5 30yr basic electric cars
    Grandchildren toys now
    Suggestions or thoughts

  2. #2
    RC Racer
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    Oct 2017
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    IL
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    What it sounds like you are describing is a T-Maxx. Part 4989 is the actual linkage that shifts the truck from forward to reverse. If you converted the truck to electric then you should not need the throttle/brake servo or the reverse servo (assuming you’re using an ESC and not a conventional Potentiometer speed control.) You should only have the steering servo. If you are using an ESC you may have to calibrate that ESC to your remote or set it up to have reverse and or brakes. Some ESCs are set up with forward and braking only, others have forward and reverse, and some have an option to choose between all three. What type of ESC are you using? What motor? Is it brushed or brushless? As a side note, I currently have a Losi XXX NT and am considering converting it to electric. Where did you get the motor mount for an electric motor?

  3. #3
    RC poster
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    Mar 2019
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    first you
    go to servocity.com
    alumni motor mount B
    mount bracket A 585494
    mount Bracket 585424
    also if you need to extend the shaft
    spark fun
    Shaft Coupler - 1/8" to 1/8" all sizes
    and they sell the shafts

    I am using a EZ RUN MAX 8 and a EZ RUN 4274 Brushless motor
    when I go into reverse with my controller the motor spins in reverse but tranny does not engage

    when I put the truck on the floor disconnected form everything I can roll it forward freely but can't roll it backwards has resistance then the tranny starts to spins

  4. #4
    RC Qualifier
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    Apr 2018
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    780
    It may have the forward only mod done to the transmission as well. You may have to pull the tranny apart to see.

  5. #5
    RC poster
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    Mar 2019
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    Thank you
    could a person unscrew the rod from the shifter inside the transmission that runs out to the servo and put a screw in the transmission opening and call it a day ?
    run forward only with the brake

  6. #6
    RC Qualifier
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    Jan 2018
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    From what I've read here, I'm guessing you are still using the T-maxx transmission, instead of the E-maxx tranny. They are very different, and it might be easier to switch them out. Not sure of this, but i'd imagine it'd bolt straight to the t-maxx chassis since both transmissions use the same screws to mount.

    It may have the forward only mod done to the transmission as well. You may have to pull the tranny apart to see.
    I was also thinking it could have a FOC. Quite a few people hated dealing with reverse on their t-maxx from what I've seen the past couple of years, cause it was more complicated than just having forward.

    3rd issue, is that the t-maxx tranny is designed to be shifted in order to switch between forward and reverse. Wondering if it has to be shifted in order to go in reverse with the electric motor. There should be a shaft where the servo linkage would normally attach to shift between forward and reverse. Try moving that in or out (whichever position it isn't in) and then power up the electronics and drive forward. If it works the same, the truck should actually move backwards. If this is the case, you either need an extra servo to shift, or like I said switch to the e-maxx tranny.

    Side note, now that I think about it, if an e-maxx tranny does fit on a t-maxx chassis, I wonder if running an emaxx with a t-maxx chassis would be a good idea. The old e-maxx seemed to have a weak chassis where it mounted to the bulkheads. The t-maxx aluminum chassis would probably hold up a lot better.

  7. #7
    RC poster
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    Mar 2019
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    I took the tranny apart no reverse inside
    what I am thinking is trying to lock the tranny so it will spin the axles in forward or reverse
    basically creating an electric motor type tranny no clutch solid connection
    any thoughts

  8. #8
    RC Qualifier
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    Aug 2015
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    420
    Quote Originally Posted by paul4350 View Post
    I took the tranny apart no reverse inside
    what I am thinking is trying to lock the tranny so it will spin the axles in forward or reverse
    basically creating an electric motor type tranny no clutch solid connection
    any thoughts
    Since the original engine doesn't reverse but now your motor does you can setup the car like it was originally and not reverse the motor to use reverse or eliminate the clutch but then I don't believe reversing the motor will work without some internal trans mods. Maybe similar to the Slayer/Revo trans mods when converted to electric?

    Sent from my VS996 using Tapatalk

  9. #9
    Marshal Double G's Avatar
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    May 2008
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    13,327
    Quote Originally Posted by paul4350 View Post
    I took the tranny apart no reverse inside
    what I am thinking is trying to lock the tranny so it will spin the axles in forward or reverse
    basically creating an electric motor type tranny no clutch solid connection
    any thoughts
    You need to lock it into second gear.

    https://www.youtube.com/watch?v=GuCcQ6RHrd0
    The Super Derecho

  10. #10
    RC poster
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    Mar 2019
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    thanks I saw that
    I have a 25 year old T-Maxx interior gears different
    I need to lock up the simple part # 4984 which spins freely in reverse
    suggestions ?

  11. #11
    RC poster
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    Mar 2019
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    took my tranny apart
    epoxied the gears together with manifold epoxy (not the clutch gear)
    lt locked the shaft to the gears frozen the directional bearing car runs like a beast in 4wd
    took my CH3 hooked up to the brake can even slow down
    electric motor forward and reverse
    so simple if you do not try to reinvent to wheel
    same concept when you converted a bike and built a mini bike without a clutch

  12. #12
    RC poster
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    Mar 2019
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    I am destroying pinion gears
    can someone recommend the type they are using that will hold up ?

    thank you

    Paul

  13. #13
    Marshal Double G's Avatar
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    May 2008
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    Using a steel spur? You need a hardened pinion. Or go back to a plastic spur.
    The Super Derecho

  14. #14
    RC poster
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    Mar 2019
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    Steel Spur

    is the pinion a 1 MOD ?

    I have been using 32T

  15. #15
    RC Champion olds97_lss's Avatar
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    Dec 2003
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    Dekalb, IL
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    2,192
    RRP (robinson racing products) has pretty good pinions. They are what I've been using on my 1/8th trucks with 4S and 6S with steel spurs.
    Expert rigging at it's best!

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