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  1. #1
    RC Turnbuckle Jr. MITCH316's Avatar
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    Recommndations on building an aluminium rear traxxis diff!

    I have posted a thread on traxxas or losi diffs...it amazes me how many people use traxxas diffs with no issues and how many rebuild them with endless issues!

    I have more issues with the rear diff than the front...the only time my front diff has gone is when a bearing has collapsed and gone through the gears (ring and bevel [pinion]) or from hard bashing and landing from a height straight on my nose (spider gears only)

    I have considered doing the losi conversion but don't feel I am quite there yet. After doing quite a bit of thinking this week and looking at mistercrash's conversion with the aluminium losi diff, I don't see why a (traxxas) aluminium diff case and cup wouldn't work.

    When I examine my diff when it strips its always one side of the ring gear and sometimes with a few broken teeth or the teeth of the bevel (pinion) gear get bent, even with shimming this is happening. This to me looks like it is caused by flex in the plastic. If I think about this logically on how my rear diff is stripping it is normally when the rear diff is not under load ie when hard braking or leaving a jump and throttling in the air.

    The shear brutal grunt of torque applied to the rear diff is amazing; I think the diff cup and diff housing by the centre drive gear connection are flexing and seem to me IMO the weak point of the diff. The other thing I have noticed which I think doesn't help is the play (slop) in the rear bulk head. When the diif and bulk head is full assembled I can move my drive shafts up and down and see about 2mm of play in each direction.

    1. What would be a good recommendation of the diff case and cup as I only know of a couple of a couple hop up stores? Aluminium or steel, what are your thoughts?

    2. Do you get hardened steel ring and bevel (pinion) gears as this would greatly improve the life of the diff?

    3. Are there any recommendations on some heavy duty bearings for the diff?

    4. Any suggestions on how to fix the play in the rear bulk head?
    Last edited by craig.mitch316; 07-20-2012 at 07:17 PM. Reason: I can't spell.
    Rock n Rolla !

  2. #2
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    You can look at several companies like flm or rd logics for diff cups. Flm gives you ring and pinion when you buy the cup. I have ran the rdlogics cups and I have not had a failure since that conversion. I also locktite the screws in as well. as foecthe diff rocking in bulkhead use some foam padding to take up the space. as for bearings I use acer racing ceramic bearings. they hold up great to brushless power
    Revenge 1/8 buggy

  3. #3
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    the reason the losi diff does so well is because it has 4 spider gears instead of the 2 the stock diff has

  4. #4
    RC Turnbuckle Jr. humayrayakongkinaon's Avatar
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    so you think traxxas should upscale the merv diffs? and maybe build it with aluminum cup?
    Quote Originally Posted by rice10562 View Post
    the reason the losi diff does so well is because it has 4 spider gears instead of the 2 the stock diff has
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  5. #5
    RC Turnbuckle Jr. mike-susieq1's Avatar
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    that would be good to upgrade. didnt think you could use different diff cups. humm all these things on here and i didnt know i've been all over this forum and searching the forum even before i joined.
    DEU 8:18 ESV

  6. #6
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    i think strengthening rear bulkhead area probably helps too

    im wondering who here has had traxxas diff failure but then
    fitted a rollcage or rear end pushrod stiffener and the diff failures have stopped

    might be worth doing the diffs and strengthening together

  7. #7
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    thats not the only reason. it is bigger/beefier in general.

  8. #8
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    I feel your pain on this issue!! The minuite i start complaining about this issue I get accused of being a bad driver, lol! I bought the Losi diffs and I will start modding as soon as I have time. I will keep you updated on my experience with using them.

  9. #9
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    I started modding my diffs today. Followed mistercrash and used the shafts from the original axles. I sawed off the threaded area ( going 1mm past the threaded area as advised) and replaced the cups with them.
    So far so good. Taking my time with this project. Impressed as soon as I took a peek inside. I can tell that it won't leak much by the way the gaskets rest.


    Last edited by Revoroller; 07-21-2012 at 03:31 PM.

  10. #10
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    No one accused you of being a bad driver. I simply said that if you are shredding diffs frequently, even after you have shimmed them, then driver error is definitely something to consider.

    The Revo diffs are definitely not best in class, but they do last longer than a handful of battery packs. Unless you are doing something wrong.

    In that circumstance, driver error could be bad driving, improper setup, or a handful of other factors.
    You might want to think about examining the possibility, because throwing a bunch of time and money at losi diffs won't solve it if that is the case.

    Good luck with the project, I hope it works out for you.
    ERBE, Summit, Thunder Tiger MT4

  11. #11
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    I think I might try those RD cups. That is what broke on mine. At least that is what I hope broke first then trashed the inside and not the other way around. They also make aluminum diff housings. anyone try those.

  12. #12
    RC Turnbuckle Jr. MITCH316's Avatar
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    This is what I ended up going for:

    http://www.teamstrc.com/index.php?ro...product_id=207 ST Racing diff[ case

    http://www.hot-racing.com/index.cgi?...RVO11C01;c=431 Hot Racing diff cup

    We will see how this goes...I am only rebuilding rear diff as I haven't really had much issues with front diffs.
    Rock n Rolla !

  13. #13
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    I ordered the HR diff cup as well. In the mean time I repaired mine with epoxy and a strip of carbon fiber wrapped around. Its holding up really well so far.

  14. #14
    RC Turnbuckle Jr. MITCH316's Avatar
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    Quote Originally Posted by X2guy View Post
    I ordered the HR diff cup as well. In the mean time I repaired mine with epoxy and a strip of carbon fiber wrapped around. Its holding up really well so far.
    Hopefully this works and holds up to the abuse we put our trucks through
    Rock n Rolla !

  15. #15
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    Revo1 if u do end up breaking Losi diff internals (like i did) then add a shim under the two large sun gears.
    http://www.losi.com/ProdInfo/Files/8...RPartsList.pdf

    Part # is LosA3501
    http://www.amainhobbies.com/product_...erential-Shims



    If you end up breaking the grey drive cups (like i did), then replace with the hardened black drive cups.

    Part # is LosA3503
    http://www.amainhobbies.com/product_...rive-Cups-Pins
    Last edited by anr2442; 07-27-2012 at 01:22 PM.
    Its All relative to your perspective.

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