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  1. #1
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    Ultimate Drivetrain Overhaul (LST diffs and drivesafts)

    Intro
    This is my take on a long standing, proven, and (somewhat) widely known modification that can be done to Traxxas Maxx trucks to improve and (nearly) bulletproof the drivetrain. Outfitting a Maxx truck with Losi LST differentials and driveshafts is nothing new, but I feel I have some insight that may help others who do this mod themselves. I take no credit for developing this modification; I just want to share my personal experiences with it.



    Part 1: Why?

    There are many advantages to doing a modification like this. I will run through a couple. The first one is strength. Big brushless systems of today paired with high power lipo setups can overpower even the newer 3.3 spec Maxx drivetrains. The Losi differentials have beefy 8mm inputs and aluminum cases standard. They also feature one piece hardened steel outdrives. The CVD style driveshafts also feature a giant 8mm axle. The stock Traxxas shafts and diffs have 6mm axles and inputs/outdrives. This can be done for around $80-100 depending on what parts you need and what kind of pricing is available at the time. For this price, you will get a lot of beef.





    Part 2: Differential installation

    I will begin with talking about how I installed my diffs. The problem with the Losi diff lies in the fact that the case is slightly narrower than stock and does not feature a stepped area around the outdrives like the Traxxas ones do. In order to compensate for this, an adapter must be made. The diameter of the collar that goes on the front of the Traxxas diff is also too small to fit the Losi.
    I chose to draw up a collar that would allow the diffs to mount in the bulkhead on CAD and use the 3D printer at my school to make a set of four. I may explore making aluminum ones if the plastic ones fail. I have also seen adapters made from plumbing parts.
    This was the result:



    I then used a high speed cutter bit on my Dremel to enlarge the diameter of the diff collar





    I also had to cut a relief in the sides of the collar to allow it to fit over the diff case



    This let me get the perfect fit



    I was then able to fit the diff perfectly in the bulks





    Much more to come as I install the driveshafts, center shafts, and axle carriers.
    "I have a car just like that from wal-mart"

  2. #2
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    Great write up so far, keep it coming. For the collar have you considered using alum? That plastic one looks pretty weak now.

  3. #3
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    I do recognize that the collar is going to be questionable. I'll run it till it breaks and then figure out a more permanent solution. Maybe I'll make a reinforced plastic one, We'll see.
    "I have a car just like that from wal-mart"

  4. #4
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    Your not interested in trying alum ?

  5. #5
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    I just don't have access to the proper equipment required to make aluminum ones. The 3D printer at my school is the only type of manufacturing equipment that is readily available to me.
    "I have a car just like that from wal-mart"

  6. #6
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    I was thinking along the lines of using a GHracing or another brand and modding like you did to the plastic one.

  7. #7
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    Wow I can't believe I didn't think of that... Well that will definitely be my choice if (when) the plastic ones fail.
    "I have a car just like that from wal-mart"

  8. #8
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    Looking good, except I have no axcess to either 3D CAD or a 3D printer. There is a way to do the same thing with PVC but it takes alot of cutting.

    Cant wait to do this mod but I dont really need it yet so Im going to work on some other areas that need work (suspention, steering, slipper)
    Doublethink: 2+2=4 while 2+2=0

  9. #9
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    I am in the process of finishing my write up but I've hit a big snag with the front center dogbone. I can't find a proper 8mm dogbone that is the correct length anywhere. I have the rear one that came with my FLM chassis but I'm having a tough time finding something short enough for the front.
    "I have a car just like that from wal-mart"

  10. #10
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    Do you know approx how long it has to be?

  11. #11
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    Very professional write-up! A++!
    This is a signature.

  12. #12
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    Thanks snowslider, and as far as the length of the driveshaft goes, It needs to have an overall length of about 70mm. I'm thinking about buying a set of Traxxas center CVDs and just using the front one. Does anyone have any pics of them without the blue dust boots?
    "I have a car just like that from wal-mart"

  13. #13
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    Part 3: Driveshafts
    The Losi driveshafts have a very convenient length that makes them perfect for use on a Maxx truck. In order to get the benefits of the shafts (discussed earlier) there are a few modifications that are necessary. First you will need to pick up a few bearings. I used the following Avid RC bearings:
    (4) 15x21x4mm
    (4) 8x16x4mm
    I then began the process of mounting the bearings in the stock carriers. I was able to press fit the larger bearing into the inside of the carrier and achieve a nice tight fit.



    I then used my high speed cutting bit to enlarge the diameter of the outer bearing hole. This process required some trial and error. I removed small amounts of material until I got a tight fit.



    Final axle fit



    still more to come as I tackle the center shafts and hex adapters
    "I have a car just like that from wal-mart"

  14. #14
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    Great job I've the same set up (LST2 Diffs) minus the steel cvds going from the diffs to the tires. Found that some one had not tightened the screw studs on the center cvds enough nor used locktight to keep screws in check. Result was what seemed to be broken splines or gearing but alas no problems was able to run this set up FOREVER ON 8000mah *****s. Any how, super good job on the build and to the point, love it. BTW using MMM 2200 combo it's good for this set up.


    ED
    Can't drive it, leading me insane, dream it!

  15. #15
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    Thanks man, I just ordered a set of Traxxas center CVDs so this build should be moving right along shortly.
    "I have a car just like that from wal-mart"

  16. #16
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    When you installed the inner bearing did you put a spacer between the bearing and the knuckle where the bearing would seat.

  17. #17
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    rd racing makes some revo/maxx knuckles with stock inner bearing but 6x16x5mm outter bearing, they are expensive but grab 4 15x21x4mm and 4 8x16x5mm from avid, it should be drop in

  18. #18
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    I didn't use a spacer between the inner and outer bearings, the fit is really tight. If they shift while driving I'll make a spacer and install it.
    "I have a car just like that from wal-mart"

  19. #19
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    Are the stock outputs on the losi diffs compatable with Traxxas shafts?
    Doublethink: 2+2=4 while 2+2=0

  20. #20
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    Quote Originally Posted by PowerToTheMaxx View Post
    Are the stock outputs on the losi diffs compatable with Traxxas shafts?
    They are, both the Traxxas shaft and LST shafts use an 8mm dogbone. The LST diffs have 8mm outdrive cups.
    "I have a car just like that from wal-mart"

  21. #21
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    Those are some beast diffs!

  22. #22
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    emax.

    Have you any part numbers for the parts you have used?

    Thinking I may try and source the parts here in the UK for my TMaxx if possible.

  23. #23
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    What is the dyamiter of the Losi ring gear?
    Doublethink: 2+2=4 while 2+2=0

  24. #24
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    Part 4: center shafts and hex adapters


    I've been done with this mod for a while but haven't had a chance to finish the write up. I had a bit of a saga with the center shafts but ultimately came up with a solution that works well. I bought the Traxxas center CVDs for the older style 3906 E-Maxx and only used the front one. I'll let the pics do most of the talking from here:


    overall drivetrain shot


    I used the dust boots from the rear shafts on the FLM extended shaft for a consistent look


    Traxxas center shaft installed

    Now I turned my attention to the hex adapters. I chose to drill out my Traxxas adapters to 8mm in order to fit over the 8mm stub axles. I could have drilled a new hole for the axle pin but chose instead to make a spacer from some brass tube.





    That competes my LST drivetrain install writeup.
    "I have a car just like that from wal-mart"

  25. #25
    RC Turnbuckle Jr.
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    Very well explained,,,congrats.

  26. #26
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    Do you have acces to the machine and would you be willing to make another set of spacers?

  27. #27
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    Unfortunately I don't have access to the machine I used to make the adapters anymore.
    "I have a car just like that from wal-mart"

  28. #28
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    Well, I've made a few set in alloy
    And I have my own lathe
    Morten SnoopMaxx
    3906 ROCKSTAR Makita
    c",)

  29. #29
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    +10 on snopp spacer.
    Top notch parts.

    Thanks again Snoop!!

    Fred
    3906 CC 1717 / MMM GA 7075 UE Khead LST2 DIFF

  30. #30
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    Sweet build. Id be impressed if you managed to break that setup. Whats the net cost on this build so far?
    Doublethink: 2+2=4 while 2+2=0

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