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  1. #1
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    Need Help Troubleshoot Tramission

    I recently took apart my summit for a deep clean after some heavy driving in the desert.
    As part of the rebuild, I added a bunch of extras and mods to the truck such as;
    - rear double orange springs,
    - new bearings set for wheels,
    - savox single servo,
    - upgraded central drive shaft,
    - RPM rear A arms,

    After rebuilding I noticed the truck is not driving smooth, jerking movements and doesn't sound right! Irregular sound of friction as I try to maintain or slowly add throttle. Videos to give an idea:

    https://youtu.be/vj3IbZFtgQY
    https://youtu.be/n4up05H33v4

    After taking it out for a 30 minute spin I also noticed the 775 motor was Hot, (couldn't keep my fingers on it for more than a second).
    To troubleshoot I started by adjusting the pinion/spur mesh, applied the paper trick and adjusted to best of my knowledge.
    Next I disconnect the front shaft, testing only RWD, same issue. Followed by disconnecting rear shaft and again testing, same. I cant really tell if the transmission by itself sounds strange.. not sure, been a while since I started the rebuild.

    I have a brushless 1800kv motor on the way to replace the old faithful 775. Worried to run brushless power into the transmission as it is, have a feeling it will tell me where the issue is by breaking it off on the first run.

    Any pointers of what I need to take apart and which parts I need to order next.

    Thanks

  2. #2
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    Does it only do that when its sitting on the stand? It might only do that when the a-arms are fully extended because when the axles are at an angle, they will move jerkily as you described

  3. #3
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    When off the stand, on asphalt, again the power doesn't seem to get to the wheels evenly, and it doesn't sound right. I can notice some strain in the transmission specially at lower speeds and if the diffs are locked. If I gas it issue isn't as obvious.
    I did set the suspension to the highest setting in the arms, maybe that has something to do with it?
    I will try to get a video with it running tomorrow..

  4. #4
    RC Champion TMaxxcrazy33's Avatar
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    Quote Originally Posted by Nelix View Post
    When off the stand, on asphalt, again the power doesn't seem to get to the wheels evenly, and it doesn't sound right. I can notice some strain in the transmission specially at lower speeds and if the diffs are locked. If I gas it issue isn't as obvious.
    I did set the suspension to the highest setting in the arms, maybe that has something to do with it?
    I will try to get a video with it running tomorrow..

    i highly doubt its cause you have it jack up. i have mine jacked up with longer pushrods and mine dosent do that and i running jumbo kongs.

    try the spur with your fingers with the truck on a stand.and see if you fill any binding. if you do take the drive shafts out and turn the drive shaft and see if you have any binding.

    i can have mine on the ground and roll the truck with just turning the spur freely
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  5. #5
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    Take out the transmission, and then try rolling it on the ground. If you still have that issue it would be easy to tell if it's an issue with the front or rear. If there's no jerking with the transmission out, you should open up the transmission then

  6. #6
    RC Champion TMaxxcrazy33's Avatar
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    Quote Originally Posted by joethejammer View Post
    Take out the transmission, and then try rolling it on the ground. If you still have that issue it would be easy to tell if it's an issue with the front or rear. If there's no jerking with the transmission out, you should open up the transmission then
    be faster if he just took the driveshafts out
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  7. #7
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    Followed your advice but couldn't really tell if the problem is with transmission, rear diff or front diff. I could move the truck by rotating the spur w/o difficulty. I did notice that the spur and clutch assembly had a slight wobble which coincided with the grinding noise (no idea what's going on there.. by design?). Adjusted the pinion/spur mesh and this helped keep the noise down. Also noticed the steel traxxas upgrade shaft has a slight bend to it.
    All rebuilt, took it out for a ride and transmission was still far from perfect. Can tell that power doesn't get distributed to the wheels as it used to.. 20 minutes into testing and spur gear stripped!! it didn't destroy it completely but pinion was spinning by itself and lots of plastic residue. Good thing spares were already on route.
    To summarize I am suspecting the following;
    - wobble in clutch/spur
    - newly installed steel drive shaft

    I will replace what I can with original kit and test.
    Need to have this fixed before Mr brushless arrives

  8. #8
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    Funny you mentioned your traxxas upgrade shaft has a slight bend in it, mine does too. It's been like that ever since it was brand new. I wouldn't be worried about it, because I've been running mine like that, it's still going strong, and it doesn't make any noise

  9. #9
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    Good to hear that, means don't have to dismantle everything to get to the shaft again. Thanks!

    This leaves me with clutch /spur to work on. Considering ordering a Robinson racing 65T spur slipper to replace the wobbly stock parts. Not cheap though and it will still be sitting on the old transmission input/drive gear shaft.

  10. #10
    RC Champion TMaxxcrazy33's Avatar
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    Quote Originally Posted by Nelix View Post
    Good to hear that, means don't have to dismantle everything to get to the shaft again. Thanks!

    This leaves me with clutch /spur to work on. Considering ordering a Robinson racing 65T spur slipper to replace the wobbly stock parts. Not cheap though and it will still be sitting on the old transmission input/drive gear shaft.
    how bad is the wobble on the spur and slipper clutch? i have wobble in mine but its not doing what yours is doing.
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  11. #11
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    Found the solution!! Hurray
    Rebuilt the transmission and noticed that I had put the drive dog carrier shim next to the plastic spacer instead of in between the two 6x12 bearings. That was causing the noise and friction. Just in time too, to run it with the new acquisition hobbywing 1800kv combo which arrived today.
    Truck rides smooth as silk now and on a 21T pinion it is scary fast.

    Thank you all for your help!! Be more careful putting it together next time

  12. #12
    RC Champion TMaxxcrazy33's Avatar
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    Quote Originally Posted by Nelix View Post
    Found the solution!! Hurray
    Rebuilt the transmission and noticed that I had put the drive dog carrier shim next to the plastic spacer instead of in between the two 6x12 bearings. That was causing the noise and friction. Just in time too, to run it with the new acquisition hobbywing 1800kv combo which arrived today.
    Truck rides smooth as silk now and on a 21T pinion it is scary fast.

    Thank you all for your help!! Be more careful putting it together next time
    why did you have to rebuild your transmission? i have had mine for about 6 years or more, and havent blew mine up.
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  13. #13
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    Quote Originally Posted by TMaxxcrazy33 View Post
    why did you have to rebuild your transmission? i have had mine for about 6 years or more, and havent blew mine up.
    I don't know about OP, but when I replaced my slipper pads, I also took the transmission apart, cleaned and greased all the bearings at the same time. I also have no idea what the previous owner did to it too, so...

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