Results 1 to 32 of 32
  1. #1
    RC Qualifier
    Join Date
    Oct 2017
    Posts
    303

    3rd front differential broken

    Hi,

    I don't understand why, but I am breaking the front diff.

    When I change it, everything is ok. After some play with the X-Maxx, it starts to make 'clac-clac-clac' sound, when I brake or when I go back.

    I changed front axles and front drive cups 2 days ago, and installed the high level front diff: https://traxxas.com/products/parts/7777X but I also broke one teeth.

    Pictures: https://imgur.com/a/RW3Qq

    Tired to break diffs, the back one seems ok as I never changed it.

    Can you help me to find how to fix this issue guys ?
    Last edited by zeflex; 10-31-2017 at 06:39 PM. Reason: Bad english fix... break, brake ... !

  2. #2
    RC Enthusiast
    Join Date
    Oct 2017
    Posts
    37
    Ive gone through one 8s and one 6s set if ring gears myself. On my 3rd set in 3 weeks time now. If anyone has some insight i wanna know lol

  3. #3
    RC Competitor
    Join Date
    Nov 2016
    Posts
    85
    Do you guys have the center diffrential?

  4. #4
    RC Qualifier
    Join Date
    Oct 2017
    Posts
    303
    I don't really know, it's a second hand x-maxx.

    How can I check that ?

    And if we have or not center differential, does it cause the issue?

  5. #5
    RC Qualifier
    Join Date
    Oct 2017
    Posts
    303
    I maybe find the issue, check the youtube video I did and let me know if that's a possibility of why my front diff breaks often.

    Seems there is minor gap on right side (vehicle front to us) https://www.youtube.com/watch?v=QmBg2-Tj_rA

    Thanks.

    EDIT: yeah I think I found why.... something broken ... crap !! https://imgur.com/a/w6qB5

    BTW, if I change this broken part, and it make no gap on the ballbearing, can I put back the old diffential (1 teeth half-broken) ?
    Last edited by zeflex; 10-31-2017 at 11:23 PM.

  6. #6
    RC Enthusiast
    Join Date
    Oct 2017
    Posts
    37
    I have the center torque bais majoby lol

  7. #7
    RC Racer
    Join Date
    Oct 2016
    Posts
    195
    The only gears anyone should be using are the 8S heavy duty versions. They are better than the original 6S and the 6S spiral cuts offerings that you are using. Part numbers:

    TRA7790 Traxxas Pinion Gear/Diff/11T Front Heavy Duty X-Maxx
    TRA7791 Traxxas Pinion Gear/Diff/11T Rear Heavy Duty X-Maxx
    TRA7792 Traxxas X-Maxx Heavy Duty Ring Gear Gear (35T)

  8. #8
    RC Qualifier
    Join Date
    Oct 2017
    Posts
    303
    Quote Originally Posted by titanse05 View Post
    The only gears anyone should be using are the 8S heavy duty versions. They are better than the original 6S and the 6S spiral cuts offerings that you are using. Part numbers:

    TRA7790 Traxxas Pinion Gear/Diff/11T Front Heavy Duty X-Maxx
    TRA7791 Traxxas Pinion Gear/Diff/11T Rear Heavy Duty X-Maxx
    TRA7792 Traxxas X-Maxx Heavy Duty Ring Gear Gear (35T)
    Thanks for links.

    What do you think about the video and pictures I posted ?

  9. #9
    RC Racer
    Join Date
    Oct 2016
    Posts
    195
    Quote Originally Posted by zeflex View Post
    Thanks for links.

    What do you think about the video and pictures I posted ?
    Time for a new lower bulkhead.

  10. #10
    RC Qualifier
    Join Date
    Oct 2017
    Posts
    303
    Yeah. I did it, I fixed everything with epoxy to avoid any gaps. Works fine now

  11. #11
    RC Qualifier
    Join Date
    Oct 2017
    Posts
    303
    I think I broke again my differential...

    Is there a way to heard/know , without run the x-maxx on the road , which differential front/rear is clicking?

    Thanks.

  12. #12
    RC Racer
    Join Date
    Oct 2016
    Posts
    195
    You need to order a lower bulkhead and replace it. Epoxy isn't going to cut it. You will keep burning diffs until you do the right thing and get the lower bulkhead replaced.

    Another good idea would be to upgrade to the 8s gears as I said above.
    Last edited by titanse05; 11-07-2017 at 04:29 PM.

  13. #13
    RC Racer Magnus001's Avatar
    Join Date
    Mar 2017
    Location
    British Columbia
    Posts
    239
    Quote Originally Posted by titanse05 View Post
    You need to order a lower bulkhead and replace it. Epoxy isn't going to cut it. You will keep burning diffs until you do the right thing and get the lower bulkhead replaced.

    Another good idea would be to upgrade to the 8s gears as I said above.
    I agree. Epoxy-ing it back together won't work. It'll just keep flexing & stripping your gears.
    V1 6s w/8s conversion
    Max5 Leopard 1090kv

  14. #14
    RC Qualifier
    Join Date
    Oct 2017
    Posts
    303
    I was not clear in my answer sorry.

    I replaced the lower bulkhead and then I put epoxy in the screw holes in order to tight everything.

  15. #15
    RC Racer
    Join Date
    Oct 2016
    Posts
    195
    OK then we at least got that far. Did you replace the different cover as well? The hit that it had to take to do that damage may have flexed the cover out of tolerance as well. You need to get the 8s gears as well as they are better than anything 6s.

  16. #16
    RC Racer
    Join Date
    Oct 2016
    Posts
    195
    Another upgrade others have done including myself is to use hot racing differental covers to eliminate the flex. I'm still on my first set of 8s gears since upgrading. I added the HR covers for free and I could see where they would make a difference.
    Last edited by titanse05; 11-07-2017 at 08:36 PM.

  17. #17
    RC Qualifier
    Join Date
    Oct 2017
    Posts
    303
    I have the gear for 8s ready to mount

    By the way, no I didn't change the cover. There is a little movement (less than half mm) of the drive cup on X axis, maybe due to the cover.

    I presume if I hear the clicking sound when I brake or reverse, it's the front diff that needs to be fixed ?

  18. #18
    RC Qualifier
    Join Date
    Oct 2017
    Posts
    303
    Quote Originally Posted by titanse05 View Post
    Another upgrade others have done including myself is to use hot racing differental covers to eliminate the flex. I'm still on my first set of 8s gears since upgrading. I added the HR covers for free and I could see where they would make a difference.
    Hr covers are around $50 ? Wow, it's expensive...

  19. #19
    RC Racer
    Join Date
    Oct 2016
    Posts
    195
    Quote Originally Posted by zeflex View Post
    Hr covers are around $50 ? Wow, it's expensive...
    Yeah they are. I bought a used X-maxx on ebay that had them on, and every other HR upgrade part, I stripped it down and put the original parts back on and resold it for close to what I paid for the OG truck. When it was all said and done I got $600 worth of HR parts for free.

    You should at least put a new plastic diff cover on the front. It had to of flexed pretty bad from the hit took to break the lower bulkhead like you did.

  20. #20
    RC Qualifier
    Join Date
    Oct 2017
    Posts
    303
    Lucky man for HR parts

    Yes I ordered new covers and 8s diffs (y)

  21. #21
    RC Racer
    Join Date
    Oct 2016
    Posts
    195
    I should have noted that I put the 8S cush/center drive in at the same time I put the 8s gears in. You may want to consider doing that in the future as well. But I haven't had a gear issue since the upgrade.

  22. #22
    RC Qualifier
    Join Date
    Oct 2017
    Posts
    303
    Related to https://forums.traxxas.com/showthrea...=1#post6420577

    I put the 8s diffs front and rear today, with 10k diff oil.

    Is that normal it sound more noisy, around the output/input gear transmission, driveshaft assembly.

    I had previously the spiral cut diffs.

    I didn't make any runs/bashing as I am not sure about this "noise"...
    I posted a video... no comment on the rust (I will fix that later) but what do you think about the noise ?

    Something looks wrong but any idea about what ?


  23. #23
    RC Qualifier
    Join Date
    Oct 2017
    Posts
    303
    I removed the whole backtrain of the x-maxx to check if I see something... nothing suspect...

    I put it back all together, removed the rear diff.

    Sound is still weird...

    Can we really mount 8s f/r diffs on 6s ? Isn't it why I get this weird noise?


  24. #24
    RC Competitor
    Join Date
    Nov 2017
    Posts
    64
    I owns the stock 8s xmaxx. I am no mean an expert, but it looks like your wheel is not spinning freely, some sort of drag or binding maybe, have you check to loosen mesh and check all bearings?

    Thing I would do is test each part, to narrow down the problem. Like remove the slipper clutch, spinning the motor by itself, and roll the truck by itself etc.
    Disconnect the center driveshaft, test each front diff and rear diff with two wheels on etc.

    Is this sound just happen recently? or it has been like this the whole time?

  25. #25
    RC Qualifier
    Join Date
    Oct 2017
    Posts
    303
    Quote Originally Posted by Townie View Post
    I owns the stock 8s xmaxx. I am no mean an expert, but it looks like your wheel is not spinning freely, some sort of drag or binding maybe, have you check to loosen mesh and check all bearings?

    Thing I would do is test each part, to narrow down the problem. Like remove the slipper clutch, spinning the motor by itself, and roll the truck by itself etc.
    Disconnect the center driveshaft, test each front diff and rear diff with two wheels on etc.

    Is this sound just happen recently? or it has been like this the whole time?
    Is your xmaxx a 8s or 6s? Mine is 6s.

    This sound is new to me, since I put the 8s diffs on the car...

    When I turn manually the motor axis, I need to force a little bit, it's not turning like an electric 5v motor, without forcing .
    Last edited by zeflex; 12-03-2017 at 03:34 PM.

  26. #26
    RC Qualifier
    Join Date
    Oct 2017
    Posts
    303
    Seems to be the front diff cover adjustment... Weird.

    The low and upper bulkhead and the cover are all new...


  27. #27
    RC Qualifier
    Join Date
    Oct 2017
    Posts
    303
    Ok fixed !

    It's because I shimmed the diffs...

    https://youtu.be/frEy3RZffL4?t=4m46s

    I removed them, then it's ok

  28. #28
    RC Competitor
    Join Date
    Nov 2017
    Posts
    64
    Glad you have figured this out! Interesting found eh? Sometimes too tight is not good, it is not normal for such powerful motor and heavy wheel to not spin freely. You can tell any binding issue very easy here.

  29. #29
    RC Qualifier
    Join Date
    Oct 2017
    Posts
    303
    Quote Originally Posted by Townie View Post
    Glad you have figured this out! Interesting found eh? Sometimes too tight is not good, it is not normal for such powerful motor and heavy wheel to not spin freely. You can tell any binding issue very easy here.
    Happy? Yes for sure but I spent too much time for nothing on it... I was going to give up and sell everything...

    Now 8s diffs on my 6s I hope they will run a long long time...

    Question guys. Do you prefer silicon diffs oil or grease? What is recommended for low temps like 0F?

  30. #30
    RC Competitor
    Join Date
    Nov 2017
    Posts
    64
    Quote Originally Posted by zeflex View Post
    Happy? Yes for sure but I spent too much time for nothing on it... I was going to give up and sell everything...

    Now 8s diffs on my 6s I hope they will run a long long time...

    Question guys. Do you prefer silicon diffs oil or grease? What is recommended for low temps like 0F?
    Yes, I just saw your other post about giving up and selling. I have been there, but knowing the Why is priceless. By posting the videos, you are also helping others down the road. So, thank you zeflex.

    I use Marine grease on mine, I figure they both are just use for lubing and waterproofing, so I just use whatever I have. Someone more experenice can jump on this with more insight.

  31. #31
    RC Qualifier
    Join Date
    Oct 2017
    Posts
    303

  32. #32
    RC poster
    Join Date
    May 2019
    Posts
    7

    You wont believe me but

    Quote Originally Posted by zeflex View Post
    Hi,

    I don't understand why, but I am breaking the front diff.

    When I change it, everything is ok. After some play with the X-Maxx, it starts to make 'clac-clac-clac' sound, when I brake or when I go back.

    I changed front axles and front drive cups 2 days ago, and installed the high level front diff: https://traxxas.com/products/parts/7777X but I also broke one teeth.

    Pictures: https://imgur.com/a/RW3Qq

    Tired to break diffs, the back one seems ok as I never changed it.

    Can you help me to find how to fix this issue guys ?
    I fought this issue all summer. I would change ring and pinion only to have it go bad in one run. So i replaced the bulkhead, no improvement. Bought new diff cups, no dice. I even shimmed it as much as it could take but still the first hard acceleration killed the ring gear. Now during all this spending and wrenching i checked the bearings each time and each time they spun freely with no issues. I had never thought to push sideways on the inner and outer bearing rings. So one day i got the idea to try to damage the bearing by pushing out the center and to my surprise there was about a millimeter of play in both directions. I had always assumed the dogbone cups wiggled cause the set screw comes loose but it was actually the bearing wiggling around. So after replacing just the diff bearings on the front and back im into my 8th run with no issues with the drivetrain. And to be clear my drivetrain asks for trouble as i run a center diff locker and proline badlands tires. So replace those junk stock bearings with some fast Eddie's or even trb. Aftermarket bearings are usually rated for at least abec 3 while stock are not rated at all so youll run cooler too.
    Enjoy.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •