I admit a Tonka truck RC conversion is not an original idea but when i thought of it I thought I was 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 any easy way and looks way cooler. Do you see the Tonka RC conversion in the picture, 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:
This picture 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 well in a small sand box ;) When it had a load it was even worse.
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 controller 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 servos ... 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.
... and here a video of the truck in action
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 :twisted: 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.
P.S. Are you interested in a kit to build your own? I would like to hear from you by sending me an email at email@example.com I recently purchased a 3D printer so I can print the axle brackets, transmission mount, and dump servo mount which makes the build much easier. The rest of the parts can be purchased via the links I provided. The hardest part is dremeling out the inside of the Tonka truck.