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  1. #1
    RC poster
    Join Date
    Jun 2019
    Posts
    4

    Help needed 2 issues, Videos included

    Hi all I have a couple of issues with the X Maxx 8s, I'll include videos

    1st - one I'll be going forward slow it's fine but in revers it seems to get knotted up also when off and you push it slowly backwards it can some times lock where it will need extra force to over come the stop, I'm running the silicon ear plug in the center diff and 500,000k in both the front and rear diffs but it did the same before swapping from the standard stuff and the gears all looked mint as you'd expect from a new car I'm leaning towards a issue with the motor or is it normal, in the video you can see when going back it seems to knot up and in the that same video at the end shows the reverse hard over right fault? My next step is to remove the motor and see if there is any knotting up still when rolling it

    2nd - issue is steering related sometimes when I reverse the steering will go hard right with no steering input and it's being held hard there by the servo (as seen in the video) also when up on my work stand when you apply forward throttle you can see the steering servo moving again with no input and then when there's no transmitter input the steering twitches it's self if left all the way over to hard right but with this I did notice if I tap the transmitter without touching the controls it resets the the steering back to where it should be.

    Any ideas on these 2 issues would be great, I'm guessing the steering issue is transmitter related


  2. #2
    RC poster
    Join Date
    Jun 2019
    Posts
    4

  3. #3
    RC poster
    Join Date
    Jun 2019
    Posts
    4
    I stripped the front rear and center diff back out the car I first removed the pinion gear and the notchy feel went so I'm guessing thats the motor but it still felt like it had a tight spot so took the front end off and I could work out the tight spot was in the rear so I then removed the spur gear shaft and bingo the tight spot disappeared so I removed the rear diff so I had just the center diff and spur shaft and sure enough rotating the center diff I could see the same place every rotation of the center diff it tightened up so took the diff apart and I could see no fault it can't be reassembled in any other position due to the 8 little guide pegs either side of the 4 bolts.

    If I held the spur shaft down in place by pressing down on the bearings and rotating the center diff I can actually feel the spur shaft being pushed out the bearing guides only probably 0.5 mm but enough to cause the tight spot when everything is bolted down and held in place so I could only assume I have a badly made center diff ring gear not centered correctly?

    But on reassembly it has been vastly improved and I seemed to have eliminated notchy reverse so god knows what I did, the only thing I can think of is I improved slightly the position of the center diff ring gear as I slackened the 4 bolts and forced it across while tightening them back up so maybe that was my issue???

    So that has kind of sorted one issue so just the weird steering issue to figure out???

  4. #4
    RC poster
    Join Date
    Jun 2019
    Posts
    4
    Thanks for all the advice and pointers .....

    Anyway as I hate it when people post problems and don't finish them with the fixes here's mine.

    The binding issue was sorted by and the answer is in the post above and a new center diff was needed to replace the badly made one that came in my new X maxx the center hole that the drive line goes into was using digital verniers only 0.3mm off center but this was enough to cause the tight spot between the center diff ring gear and spur shaft gear when all clamped down in place.

    The strange issue with the steering where when throttling it would start to turn right slowly it's self with no transmitter input and if left it would hit it's end stop and by tapping the transmitter on something hard it would center it's self again, I had tried resetting and re binding with no change. This was due to a faulty transmitter I ordered a new replacement and it arrived today and after binding and setting it up no more steering issues....

  5. #5
    RC Turnbuckle Jr.
    Join Date
    Oct 2016
    Posts
    4,015
    Didnít see this thread, it does sound like the transmitter was obviously an issue. The driveline you troubleshot well and figured it out. I donít know what anyone could have added that you werenít already looking at.


    Somehow builds are never done....

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