Bigfoot Nation: a single motor narrowed Twin Force project

Discussion in 'Kyosho RC Monster Truck Forum' started by HawnMT, May 19, 2013.

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  1. May 19, 2013 #1

    HawnMT

    HawnMT

    HawnMT

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    ...or single force? I don't know.....After finally getting my Mad Force VE dialed in I've gotten around to a project that I've wanted to do ever since getting one of these Kyoshos, a narrowed TF/MF. Even way back in my crawler days I've known that the TF/MF axles could be narrowed fairly easily but it wasn't until I got one that I started to ask the question if the chassis could be narrowed right along with them. I'm sure at some point someone has done this but I couldn't find any threads on any site covering it but after some quick measurements it looked doable.

    The idea is to get a slight smaller truck that is more the size of a Clod or TXT. I'm hoping it also makes for a more agile truck but if I can maintain the performance in the smaller package that'll be good enough.

    First step was narrowing the axles. I'm not going to cover it in detail because it's pretty straight forward. I shortened the "long" side so it's the same length as the short side. All that required was cutting the long side of the diff case a little and grinding the inside so the outer tube would slide in it. I am using the two short dogbones for the rear axle and bought a pair of OFNA CVAs for the front.

    [​IMG]

    The chassis and transmission was going to be the hard part. Here's some pics of the stock chassis plates and trans:

    [​IMG]

    Bascially I would be taking out one side of the trans, leaving just a single motor mount. Since the trans is offset to one side it's almost easy but I couldn't just cut that one side completely off because I had to leave room for the spur gear. So I would remove most of the empty side side of the trans and that sliver of space on the single motor side.

    [​IMG]

    [​IMG]

    Instead of cutting up the stock plate, which I could have done, I asked JoeWorks to cut me a blank aluminum plate that I would drill out to be the new narrower trans. Since I am only planning on running a 540 sized 4-pole brushless motor I shortened the plate too. Here's the new plate alongside the stock one. (the larger stock plate is upside down)

    [​IMG]

    Here's the new narrower, more compact transmission all buttoned up.

    [​IMG]

    For the side plates, I cut slots for a 2s battery pack and I took some of the length out of them since I am planning a different suspension setup.

    [​IMG]

    here's the plates and trans all put together.

    [​IMG]

    Got everything mocked up so I can figure out the shock towers, body mounts, and steering setup. It already looks like I'll have to shorten the chassis a little more in the front to make room for the steering servo on the axle. I have a 4200mah shorty lipo pack in it and it's the perfect width.

    [​IMG]


    Still have a lot of things to do but I'm pretty happy I was able to get this far with very few problems. Hope the rest goes as smooth.
     
    Last edited: Jun 15, 2013
  2. May 19, 2013 #2

    TXT-2.0

    TXT-2.0

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    Dang Kent that's awesome ! Great job so far ! What kind of power will you run through it now
     
  3. May 19, 2013 #3

    Tad

    Tad

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    Looks good Kent. I think a narrowed twin is the best width with clod tires you can have.

    I harrowed a trans up and shortened the shaft also so it don't stick so far back. Not a great pic but you can kind of tell in this one.

    [​IMG]
     
  4. May 19, 2013 #4

    HawnMT

    HawnMT

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    Thanks guys.

    I figured someone had to have tried it before and I should've guessed it was Tad who did it. lol I didn't even think to shorten the top shaft on the trans, I'm going to look into doing that to make room for the esc on the plate. I like those straight axles on the on your truck Tad.

    Tom, I'm keeping this one low budget so the electronics, while new, will be cheap stuff. The esc will be a Turnigy 60amp esc. The motor will be one exactly like the one I used on the clone project, the 4370kv 4-pole brushless. And the steering servo will be a Turnigy 1258(Savox knockoff) which is both high speed and high torque. The servo wasn't that much cheaper that the real one but I like the fact that it doesn't have the heavy amp draw that the Savox does and it doesn't get hot.

    This truck is really meant to test the performance of the narrowed axles in a more stock configuration. I do have a more high performance project in mind for the future that I've already started collecting parts for. I already have Mad Force axles(at this point I plan to narrow them), new style Emaxx brushless trans, Tekin Pro4 4600, and Castle MMP. I will make a custom CF chassis for it but I haven't decided whether it will use the stock arms or a 4 link system.
     
  5. May 19, 2013 #5

    Tad

    Tad

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    The tube clean the a le up a lot. A friend had them made several years ago. Wish I could get him to make more. He made them for next to nothing.

    I love seeing these trucks getting some mods. Most people don't change them from stock much at all. I need to finish up a few I have started.
     
  6. May 20, 2013 #6

    80sinSTL

    80sinSTL

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    Looking good, Thanks.
     
  7. Jun 15, 2013 #7

    HawnMT

    HawnMT

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    I've been working on this truck little by little but I haven't been updating or taking many pictures. The main reason for that is when I run into problems I just work through them and forget to take pics. First major problem was the trans plate, it didn't offer enough adjustability. I could get a 18t 32p pinion in there but that was it. Luckily JoeWorks gave me two blank trans plates so I made another plate rather than swiss cheesing the other one.

    When I decided to do this project one thing I wanted to have was link mounted shocks. After fighting with direct mounted shocks on so many of my trucks I knew I wanted a easier to tune system on this one. I asked Brad at ThunderTech Racing if he could cut me a set of their TF/MF traction bars out of thicker material and told him why. Brad did me one better and offered to put the shock mounting holes and bosses in them. Here's a pic of what I got, 1/8" CF traction bars with shock mounting holes.

    [​IMG]

    Brad also added this nice little touch, a recessed area for the plastic bushing to go into so I could use the stock mounting screws(I still used the longer screws since I had already planned to).

    [​IMG]

    After getting those fitted up I was then able to work on the steering setup. I basically copied the TTR Eliminator steering system but I modified it to fit in the narrowed axle. Since there's no longer a "long" side to the axle I flipped the servo position over to the the opposite side (from the TTR system) to counter the weight of the slightly offset motor. The servo plate barely fits in that tight spot.

    [​IMG]

    The linkage ended up being a real pain. The long drag link is froma Ground Pounder and the steering link is an 80mm aluminum tie rod. For whatever reason straight links wouldn't work, they kept binding against the wheels, so I bent them just like I did for my Ground Pounder with Clod rims. It took a lot of fiddling to get this to work with maximum steering angles.

    [​IMG]

    Next step was the shock towers. The shocks I'm using are Losi Comp Crawler shocks with soft white springs and 30wt oil to start. The height of the towers was determined by cycling the chassis up a down a determining how much travel I could get without any significant wheelbase changes. The reason for this is so the suspension cycles smoothly and won't be trying to "pull" or "push" the axles in and out. After I had that I positioned the shocks so when they are fully extended and fully compressed they are near those points. So that determined the height and I made them wide for a large contact area on the bottom with the chassis and also wide on top thinking I would mount the body mounts up there. Cut with a hacksaw and filed smooth.

    [​IMG]

    I chose to attach the towers to the chassis with alumalloy. I'm a little worried about the joint being able to hold up but the setup was much easier with the towers being in line with the chassis.

    [​IMG]

    I got everything put together to check fit and function then tore it all down for paint. Here's where I'm at now, I still have to mount the esc and receiver and change the motor bullet to 4mm then paint and mount body.

    [​IMG]

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    [​IMG]


    I've chosen what this truck will be, it's the Larry Swim version(black wheels) of Bigfoot Nation.

    [​IMG]

    [​IMG]
     
  8. Jun 15, 2013 #8

    william g

    william g

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    Super shafty carries the straight axle tubes for mad/twin force axles, as well as other parts for them
    http://supershafty.com/


    .
    [​IMG]
     
  9. Jun 15, 2013 #9

    KingClod27

    KingClod27

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    Awesome Kent..
     
  10. Feb 19, 2014 #10

    HawnMT

    HawnMT

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    Small update to this project. I've had it sitting basically waiting for me to do the body(mostly waiting on the graphics to be done, which they now are) so I finally did a mod I've been wanting to do for awhile, Revo driveshafts. I had the pinion shafts and the trans output shaft turned down from 8mm to 6mm and drilled for screw pins(thanks Josh). Here's the result, Revo center shafts(not the bulkier Revo axles) modded to serve as driveshafts. The reason for having such a small gap is because the shafts don't need a lot of travel in this application and I wanted the gap as small as possible to keep debris out.


    [​IMG]



    I'm finally going to get the decals done and finish the body. Also have two other Mad Forces coming out at the same time as well a custom chassis Mad Force race project going about to start.
     
  11. Feb 20, 2014 #11

    william g

    william g

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    nice work
    wish the super shafty straight axles were available
     
  12. Feb 21, 2014 #12

    HawnMT

    HawnMT

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    Seems Rick isn't carrying a lot of MF/TF stuff nowadays. I actually have a set of the straight tubes, I'm saving them for a future project similar to this one but with a race designed chassis. The tubes seem really simple and look like they would be hard for a machinist to make.
     
  13. Feb 21, 2014 #13

    william g

    william g

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    Agree, he's out on a LOT of items.
    As for the tubes, they were not cheap, but looked good and functionally perfect so to me worth it.
     
  14. Feb 23, 2014 #14

    reggie1

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  15. Feb 24, 2014 #15

    bartshobbyshack

    bartshobbyshack

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    Rick should be getting the lock out tubes in stock any day now. Truck looks great so far Hawn.
     
  16. Feb 25, 2014 #16

    william g

    william g

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    ordered a set of rear tubes last night :D
     
  17. Sep 5, 2017 #17

    HawnMT

    HawnMT

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    I'm bringing this thread back from the dead because I've finally finished it, sorta. I never felt right about the chassis I cobbled together for this so I finally spent the time to hand cut a new for it. It allowed me to mount the shocks higher on the chassis thereby lowering everything a little more. I actually made a slight error and lowered the battery too much so the traction bars are in the way when I try to remove it. So noiw every time I want to change the battery I have to unscrew both rear shocks from the chassis so the axle drops out of the way. Since our sticker guy here went out of business I couldn't do the Bigfoot Nation stickers but I do plan at some point on making that body. For now I put my old CAT body on it.

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