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  1. #1
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    uhh ohh.... broke it.

    ok i broke my emaxx out bashing on lunch. brought it in to work here and i think i busted the rear diff. seems like its only front wheel drive.

  2. #2
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    Make sure you didn't lose a pin in the drive shaft. May be an easy fix.

  3. #3
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    A driveshaft probably just broke. Cheap fix
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  4. #4
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    Ya, worst case is a diff, but more likely you stripped a hex, or sheered a pin or shaft.

    Diff: think about upgrading to LST diffs, it takes alot to break a traxxas one and it sounds like you wernt trying very hard.

    hex: new wheel is needed, think about using a 17mm hex wheel

    Pin: if its the hex one, you can just replace it with a bit of a nail or drill bit, if its the threaded one that connects to the diff, then you need to buy a replacement, like $3

    Shaft: replace it. Look at CVDs but better to break a shaft then a diff.
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  5. #5
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    Quote Originally Posted by PowerToTheMaxx View Post
    Diff: think about upgrading to LST diffs, it takes alot to break a traxxas one and it sounds like you wernt trying very hard.
    i was doing some bashing at work. jumping some loading dock ramps. and whipping doughnuts, drifting and power sliding the sand, when this happened i had just landed a couple foot jump off the ramp.

    ok so after dinner i had just a few moments to do some invenstigating. i dont know if there is play in the spur and pinion gear. it feels like the motors have almost a pulse to them as they turn. the larger gear taht is in there is a 88 tooth. is that normal? but i know it does seem to have about a quarter of a turn before it seemed to do anything. and the right side seems to be binding a bit. but i dont really have time to work on it right now.

    thanks for the input!!
    Last edited by hatethmpr; 04-25-2012 at 11:10 PM. Reason: spaced gearing.

  6. #6
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    I would guess that parts of the drive-train have wore down over time, causing the failure to happen, and probably explaining the 1/4 turn play. The plastic joints can build up a lot of play before they fail and it's a sign they are about to fail. Pull the wheels off the truck and inspect the driveshafts it should show you where the binding is occurring in the rear, also check pivot ball caps. Another reason I had my drive-train fail was the large steel gear in the differential loosened and tore itself out of the plastic housing it screws into. If you don't wanna upgrade diffs right away Ebay sells completely assembled diffs off the newer traxas models for a pretty reasonable price, it might be a good place to buy a complete set of driveshafts if it looks like all of them are going down the tubes. (although CVD's are pretty nice I love mine)
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  7. #7
    RC Champion trax de max's Avatar
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    the large gear (spur) is probably 66 or 68.
    the pulse you feel turning the motor is just the magnets, normal.The quarter free play is also normal.
    i think your diffs. Probably rear centre shaft pin missing or yoke snapped if both rear wheels don't turn with front. If only one turns the the centres ok and it's the side that's not turning.
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  8. #8
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    more likely you stripped a hex, or sheered a pin or shaft.

  9. #9
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    i didn't see a missing pin last night on any of the shafts. the funky noise seems to be coming from the tranny. but also some noise from the rear diff. the spur gear says 88t on it. if its a hex i just need new wheels? and no shaft is broken, granted it may be inside. but im not seeing it.

  10. #10
    RC Champion trax de max's Avatar
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    what spur you running to have 88. I'm sure the largest new style is 68 and largest old style is 72, if the tranny has been modded to fit an 88 maybe it is something in there somewhere.
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  11. #11
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    ill try to get a picture uploaded here later tonight. have to take care of the kid after work. and im wondering if the diffs from the 3908 is the same?
    ill ahve to look into a tranny.
    Last edited by hatethmpr; 04-26-2012 at 11:27 AM. Reason: im not smart.

  12. #12
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    havent had tome to upload a picture or a video. took one of each. the spur gear is a 68. that must have been the improper lighting that i was using. so now that is sorted out. i could use some more insight as to how to fix this problem. hopeing for help from here so i dont have to find another site to use for help.

  13. #13
    RC Champion trax de max's Avatar
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    It will be difficult to say whats wrong as we don't have the truck in front of us, we can only point you in certain areas.
    Flip it on the roof and turn both rear wheels, look to see if centre shaft turns.
    If it turns then check the connection from tranny to shaft.
    If it doesn't turn check connection from shaft to diff.
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  14. #14
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    I would just haul the diff out and open it up to remove all doubt there.

  15. #15
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    ok guys, took it out last night. both front and rear diffs and axles all are in good shape.

    did find out that the tranny is making some really bad noises. the spur gear seems to be bent. or wobble while it is spinning. it also appears that all of the spur and pinion gears are worn pretty bad.
    i have a picture but i cannot get to a file sharing site at work. which really sucks. i also have a video of the sounds. but yet again WEBSENSE is not fun. (self edited for language.)

  16. #16
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    so i dont know if anyone has been reading this or not. but after last nights run. i realized that my motor esc and batteries were all very hot. now i dont have a temp gauge. but i know that the 550s were very hot to the touch. along with the batteries and the exc.

    now i only got about 25 min run time off of the 3300 mah and the heat was after running WOT for a few min. then running in between half and 3/4.
    running concrete and shorter grass. fresh cut. so i dont think that the grass has anything to do with the heat.

    BUT what can i do about this? is there anything i can do to help cool this thing? im going to create a photobucket account so that i can get some pictures up here.


    this is the noise. you cant see the bend in the spur. but its a good loud noise.

    http://www.youtube.com/watch?v=rSoOiem6dr8

    since i dont have the account for photbucket yet the pictures i wont be able to upload.

  17. #17
    RC Champion trax de max's Avatar
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    check the gear mesh on both motors to spur,sounds like one or both is just skimming instead of a good mesh.
    If thats not it move the motors away from spur and turn each gear to see whats making noise.
    Last edited by trax de max; 05-04-2012 at 05:08 PM. Reason: spelling
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  18. #18
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    Quote Originally Posted by trax de max View Post
    check the gear mesh on both motors to spur,sounds like one or both is just skimming instead of a good mesh.
    If thats not it move the motors away from spur and turn each gear to see whats making noise.
    just took the tranny out. opened it and checked the bearings. it seems as if the bearing behind the tranny has some slop to it. it also seems as if the spur is warped. i tightened down the slipper to see if that would help. but i wasnt able to charge the batteries to check it. but it was still a little on the loud side. maybe i can check it at work tomorrow.

  19. #19
    RC Champion trax de max's Avatar
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    what maxx is it
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  20. #20
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    Quote Originally Posted by trax de max View Post
    what maxx is it
    3905 bought used.

  21. #21
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    Check to see if your motor plate is bent. After a few good crashed the weight of the motors may cause the plate to bend. If it looks suspicious lay the plate on a flat surface to see where it's bent at. Besides that, I'd recommend taking look at the spur gear spin with the motors backed off. If it feels rough or still wobbling, the spur gear / bearing / input shaft might be damaged.

  22. #22
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    Quote Originally Posted by GaiginRC View Post
    Check to see if your motor plate is bent. After a few good crashed the weight of the motors may cause the plate to bend. If it looks suspicious lay the plate on a flat surface to see where it's bent at. Besides that, I'd recommend taking look at the spur gear spin with the motors backed off. If it feels rough or still wobbling, the spur gear / bearing / input shaft might be damaged.
    tonight i will see about the motor plate if i have time. but im thinking about trying to find that bearing. it shouldnt be that hard to replace a tiny bearing like that.
    along the same lines. im wondering if a tranny from another truck would fit into it? keep one as a spare and replace parts needed per tranny.

    this weekend i should be getting a 3908 roller with wheels and a tx/rx. so i wont need much to get it up and running. sounds like its gonna be a fun summer!!

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