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  1. #1
    RC poster
    Join Date
    Nov 2010
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    7

    tmaxx transmission surging problem

    Ok, I have an older 2.5 chassis that I've have upgraded to a complete 3.3, also upgraded transmission input shaft to the 3.3 and clutch assembly. I've been having this issue even before the engine swap that the tranny will click and surge while at idle, as if the gears are binding. I've adjusted the slipper clutch to try and resolve it and no changes. I also had to replace some internal gears due to wasting them, but no change otherwise. When I accelerate, it drives and shifts normal, this is only going on at very low rpm and idle. Is there any centrifugal clutches inside the transmission causing this?


    Also on another note, since the engine swap, I've been twisting the heck out of my driveshafts front and rear including the ones coming from the transmission, I replaced the centers with the Traxxas 4949r CVD and only the rear will fit, any ideas.

    Thanks for your time.

  2. #2
    RC Qualifier
    Join Date
    Jan 2008
    Posts
    548
    is the tranny black with reverse?if so that may be normal.some call it bucking.

  3. #3
    RC poster
    Join Date
    Nov 2010
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    7
    yes it is, its the origional 2.5 tranny. no way to fix it?

  4. #4
    RC Champion
    Join Date
    Mar 2010
    Location
    Louisiana but originally from Ottawa, Canada
    Posts
    1,541
    Yes you can fix it there is a no buck mod, but most just do away with the rev, and go with FOC..
    T-Maxx Predator 3.3
    Shockwave 36

  5. #5
    Marshal Double G's Avatar
    Join Date
    May 2008
    Posts
    13,501
    Either go forward only or search the T-Maxx forum for the no-buck mod to the tranny.
    The Super Derecho

  6. #6
    RC Racer
    Join Date
    Sep 2010
    Posts
    155
    Quote Originally Posted by Chewie View Post
    Also on another note, since the engine swap, I've been twisting the heck out of my driveshafts front and rear including the ones coming from the transmission, I replaced the centers with the Traxxas 4949r CVD and only the rear will fit, any ideas.
    I'm pretty sure the 4949r is only for the t maxx 3.3, I'm not sure about the part number for the other driveshafts but I think traxxas makes them

  7. #7
    RC Racer
    Join Date
    Aug 2010
    Location
    Lexington, KY
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    122
    a revo spec center can be cut down to fit. won't twist and snap so easy.
    formerly 1bigemaxx, now more nitro than not!

  8. #8
    RC poster
    Join Date
    Nov 2010
    Posts
    7
    thanks for the replies, I might just go with the FOC mod, at least Im not alone when it comes to this issue.

  9. #9
    RC Turnbuckle Jr.
    Join Date
    Feb 2002
    Location
    Central New Jersey, USA
    Posts
    13,880
    To eliminate the bucking and jerking, you'll need to get the idle lower. This requires a sharp tune on the LSN so the engine doesn't stall out. As mentioned, there is a modification you can do so the transmission is constantly engaged. Search for "no buck mod" and you'll find a lot more information. It makes it so that the idle speed doesn't need to be perfect for switching between forward/reverse. (but it does need to be within reason)

    I don't race, I just bash around - and I like the convenience of reverse. It was one of the major innovations in nitro RC when the T-Maxx was introduced. One way to help get a steady, reliable low idle is to buy a MIP heavyweight steel flywheel. All of my TRX engines have them.

    http://miponline.com/store/mip3079.html
    Speed costs money, how fast do you want to go?

  10. #10
    RC Qualifier
    Join Date
    Jan 2010
    Location
    Montgomery AL
    Posts
    950
    My 2.5 Maxx did buck and surge right out of the box, Break-in went perfect and the tune seemed to be right on the money. Within 2 weeks I had done the FOC, after GOOD advice from folks here, and from that moment on .... perfect.
    US Navy retired, now - FAA air traffic controller

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