Frankenstein Build
 

After the disorganized mess my VFD Capra build thread turned out to be I will probably keep this one short. This is a 6x6 I've been trying to piece together for a little while. It's got a VFD transmission with a custom skid sitting between shortened Traxxas TRX6 rails. The rear axles are TRX6 and the front axle is SCX10 iii in a Vitavon housing converted to 4 link and servo on axle. I have a set of 6 Probuild wheels for it and 2 of them are currently on the front but with the difference in width between the Traxxas axles and the Axial axles I need to figure out some spacers to get them close to the same. The rear axle still has the lock/unlock function but there is a spool in the middle axle. My thought was that using the VFD DIG with the rear diff open would tend to make the truck pivot around the middle axle giving tighter turns. No idea if it will actually work. All in all the wheelbase has been shortened 35mm compared to my stock TRX6 and the FJ45 body looks like it will sit nicely in front of the middle tires.

Re: Frankenstein Build
 

This could be VERY interesting!

I like where your head is at, nifty component choices..."thumbsup"

Re: Frankenstein Build
 

Looking forward to seeing this come together! I’m also super curious how you setup the servo on axle for ar45p.


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Re: Frankenstein Build
 

It's kind of hard to get clear pictures of the mount because it's pretty well tucked in but there really isn't much to it. The truss on the Viavon housing is beefy so I printed a block that attaches to it that the upper arms connect to and then mounted a Vanquish Capra servo on axle mount on top of it. It's a little taller than I wanted but it was necessary to get clearance for the link ends. I think it's still sits lower than it would have on the chassis and the weight is on the axle which is a plus. When I pull this thing apart, which I will inevitably do, I'll take some better pictures.

Re: Frankenstein Build
 

Lots of cool stuff going on here.... looking forward to seeing it come together!

Re: Frankenstein Build
 

Here's a couple of pictures of the SOA mount. The 2 stainless screws are where the links are attached. Not much to it.

Re: Frankenstein Build
 

Simple yet affective.. I like it man. I know a lot of people who would pay for one haha


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Re: Frankenstein Build
 

Quick update. I decide to try to fit the extended VFD transmission out of my VFD Capra to the 6x6 so I'd have the option to use 550 can motors. This led to clearance issues with the TRX6 rails unless I wanted to go back to the stock wheelbase. Rather than do that I knocked together a flat rail chassis that solved the clearance problems and left the wheelbase close to what I originally planned. The chassis is currently 3d printed but once I make some adjustment to the link lengths and figure out the mounting for the dig and diff lock servos I'll route them out carbon fiber.

Re: Frankenstein Build
 

Man you never cease to amaze, that’s pretty damn impressive. Looking forward to seeing this thing completed


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Re: Frankenstein Build
 

Keep it coming. Way to be different. I enjoy the mix and match builds the most.

Just curiously, what is the width difference between a TRX4 and a SCX10.3?

Re: Frankenstein Build
 

Amazing. The ultimate 6x6 crawler build? I love it.

Re: Frankenstein Build
 

Thanks! I'm looking forward to seeing it done too. I just need to try to avoid the never ending changes my VFD Capra went through. The poor Capra is currently in pieces since I took it all apart to do some painting a while ago, got busy doing other things, and managed to lose most of the 3d printed parts. Reprinting the parts would be simple enough except my 3d printer files are even more disorganized than the Capra build thread was and I had dozens of different versions with minor changes for fitment, geometry changes, etc of pretty much all the parts. I don't actually remember which ones I ended up using. Getting old sucks...

Re: Frankenstein Build
 

Thanks. I think I enjoy doing this kind of stuff as much as I do driving.

The TRX6 axles with the hexes they came with (5mm) are 198mm wide at the hex face. I don't know what the AR45P normally comes with for hexes but with the 6mm ones I'm using the width is 193mm. So cross pin hole to cross pin hole the width difference between the Traxxas and the Axial would be 7mm.

Re: Frankenstein Build
 

I don't know about ultimate. My stock TRX6 is pretty hard to beat in most stuff except when things get tight. This is just an experiment to see if a slightly shorter 6x6 with the weight more biased to the front might be a little more maneuverable and still climb like a goat. Mostly it's just an exercise in keeping my old brain active and hopefully extending the time before it turns to oatmeal.

Re: Frankenstein Build
 

Hahaha. I think it will help. I think my own TRX6 crawls better when I have a little two cell all the way in the front. Mine is not that modified, I cut up the body to stop it from dragging on every object known to mankind and obviously a few new internals

Re: Frankenstein Build
 

Well, I've gone from 6x6 to 2x2.

I've Made a few redesigns and solved all the clearance issues I had as well as made the main part of the chassis fit better inside the body. Now I just need to figure out the rails to hang 2 axles off the back of it.

For you that might be wondering why I've done the chassis in multiple pieces, it's partly due to the capacity of my 3d printer and partly because by making it modular it's much easier to make adjustments to things without having to redo the whole chassis. Since I'm just winging it with this design I try to use dimensions and geometries from actual RC products but I never know how well they might translate to what I'm trying to do. My CNC is big enough so I can probably do the whole rails as one piece but I think I'll still leave it as multiple pieces if I can make it solid enough.

Re: Frankenstein Build
 

For those of you that are building 6x6's using the G-Speed chassis, I'm curious how much torsional flex/twist you are seeing in the back half of the chassis. I've only seen pictures of the G-Speed chassis so I've been assuming the it is 3mm carbon fiber. I've tried making the rear section of my chassis from 3x12mm good quality 4K carbon fiber plate and even with what I thought was probably overkill for cross bracing I had noticeable twist when lifting the rear axle. Vertically there was no flex at all. For comparison I picked up some cheap 1/2" aluminum c-channel from Home Depot and even with minimal bracing there was no twist at all so I know that it possible to make a multi-piece chassis and have it be solid but the aluminum is heavy compared to the carbon fiber and kind of ugly.


Is chassis twist a thing with these longer carbon fiber chassis' and not an issue? Or am I doing something wrong?

Re: Frankenstein Build
 

How wide is the chassis out at the ends compared to the skid? With the gspeed I was running a vader skid, I believe 78mm wide? Then in the front I had the chassis pinched down to 67mm for the lay down servo mount and 70mm out back for the divorce setup tcase. I had minimal bracing IMO but I don’t recall that much flex. Pinching the chassis down like that adds quite a bit of rigidity.
Hope this helps man, this things badass


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Re: Frankenstein Build
 

You hit on something I hadn't noticed when looking at pictures of the G-Speed chassis. The rails are pinched down from the skid to the front/rear. I had to make my skid 3mm wider (81mm) than the stock VFD skid in order to get the clearance I needed to run 4 link rather than the 3 link and panhard that the Vanquish chassis runs. With 3mm rails the overall chassis width is 87mm. The rails for the rear of the chassis are bolted to the inside of the main chassis rails and run straight back without any narrowing so 81mm width their whole length. I'm guessing this is the problem. I'll have to try to design some cross bracing that allows the rails to pinch a bit toward the rear and see if that helps. The front isn't an issue since the VFD ties the skid and the front of the chassis together so it can't flex.

Thanks for pointing that out. I was beginning to think maybe I should give up on the short wheel base and just get a G-Speed chassis to build. That isn't really me.

Re: Frankenstein Build
 

Glad I could help man, I hope you figure something out!


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