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Thread: Tonka truck RC conversion with dump and 4WS

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Old 06-12-2014, 03:07 PM   #1
Join Date: Apr 2014
Location: Up North
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Thumbs up Tonka truck RC conversion with dump and 4WS

I admit a Tonka truck RC conversion is not an original idea but when i thought of it I thought I would be the first ... that is until I searched the web, D'oh. Yes this has been done before but in my opinion everyone else did it the hard way and failed to preserve the original look ... here is the easy way and looks way cooler. Do you see the Tonka RC, if it wasn't for the wheels it would be hard to pick out:

I started with some left over parts. I had an extra parts from recent transmission upgrades and such to my Axial SCX10. The majority of the guts are from a Axial SCX10 and wheels from a Axial Wraith Poison Spyder. Lets start with an overview:

The picture below shows the most important key component and yet the simplest. there are four little 'L' brackets that hold the two axles on. They are all built the same and they are simple. I use the original Tonka truck as the frame and note that the SCX10 axles are a perfect fit.

The second important piece of the puzzle is the transmission mount. I seen others try and keep the orientation of the transmission. This is not necessary and since I have such a short wheel base I needed the drive shafts to be more in line in order to get it to work. Again a simple 'L' bracket with it mounted on the side did the trick. Note this picture shows the rear has the normal fixed axles. I admit I first completed the truck with normal 2 wheel steer but with the short wheel base and locked axles the thing wouldn't turn. When it had a load it was even worse.

Below you can see an overview the the underside. Lets review the basics:
a) transmission: SCX10 with Axial stock 20T and stock gears
b) drive shafts: I learned it is best to work with the older style shafts as the new CV type cannot be shaved to get to fit the short distance in the front. Turns out Traxxas driveshafts will fit with a simple drilling out of the center D by hand with a drill bit.
c) ESC: any ESC will do, this is a top heavy truck so no need to make it fast
d) transmitter: any 2 channel will do because I used Bastens Quadsteer to control the 4WS
e) axles: you can buy just the axles via part number AXI30488
f) servos: any standard servo will do for the steering but the dump bucket will take a stronger 300oz-in servo... more on this later.
g) wheels: I like the size of the wheels that came with the Wraith Poison Spyder and they are cheap! The tread of the BFGOODRICH KRAWLER looks about the right for a dump truck.

Next lets talk dump. Many go with expensive actuators but I decide to go cheaper. I found an aluminum servo arm that was about 2.5 inches long then mounted a standard 5x7 bearing using one of these Traxxas 3642 shock screws. But as I mentioned earlier the servo had to be at least around 300 oz-in like found here. Mounting the servo was simple, a servo mount would have been better than the zip tie I used but I didn't have any extras laying around. With a flip of the third channel toggle switch the arm dumps the box. I should note that there were two rivets as a pivot point for the bed, this was way too tight. I had to drill them out and use a bolt. This provided a much less resistance for the servo.

In the end here is the finished look

... and here is the video

Tonka RC Conversion with Dump and 4WS on YouTube

Notice that the bed falls back into place. I was thinking I would need a spring to bring it back but turns out it really isn't needed. I can haul almost 8 lbs evenly distributed weight which is more than enough for my 4yr old son to play in the dirt ... that is if he can rip the controller out of my hands

There are plenty of other details about the tuck that I could continue blabbing about but lets face it ... its the pictures and videos that are interesting while the rest is just boring blah blah blah.


Last edited by PatsPosts; 09-12-2014 at 07:23 PM. Reason: added information about drilling out rivets for easier dump action
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Old 06-12-2014, 03:31 PM   #2
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Default Re: Tonka truck RC conversion with dump and 4WS

Ha ha I love it! Looks like fun.
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Old 06-13-2014, 02:18 AM   #3
Join Date: Feb 2014
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Default Re: Tonka truck RC conversion with dump and 4WS

Nice job on that! Interesting way to use the dump feature for sure. Next you need to convert the excavator to load the truck ;)

This looks like it would be a fun build, may have to do one of these.
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Old 06-13-2014, 12:03 PM   #4
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Default Re: Tonka truck RC conversion with dump and 4WS

Super cool man, I love it
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Old 06-13-2014, 09:50 PM   #5
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Default Re: Tonka truck RC conversion with dump and 4WS

So cool. I have an old metal truck similar to a Tonka from when I was kid I have thought about doing something like this to. Looks like a hoot to drive
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Old 07-25-2014, 12:42 PM   #6
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Default Re: Tonka truck RC conversion with dump and 4WS

Too damn cool! I watched the video. How about putting some stick on tire weights under the bed to help with it coming back down? Is there a way to slow down the box servo?
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Old 07-27-2014, 02:58 PM   #7
Join Date: Apr 2014
Location: Up North
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Default Re: Tonka truck RC conversion with dump and 4WS


Glad you liked it. My boy is still having fun with the truck and so am I.

I can slow down the server with my radio by deceasing the acceleration of that channel. It comes down to the options available on your radio. Honestly, it works as is. No need to change anything with the dump servo.

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