In this instructable, I will attempt to provide a detailed guideline on how we converted a 1980's Tonka Dump truck into a working RC robot. I've broken the steps down a little more in detail in order to show what I've cut out and moved to make room and provide storage. Since this robot was assembled prior to creating this instructable, I hope this serves more as a guideline when thinking of creating your own.
Step 1: The Break Down
1) Remove steel pins that connect the wheels and dump truck bed with any good power tool or hand tool of your choice as shown in picture 2
2) There is a rivet tucked away in the neck of the truck that connects the cab to the bed. (Note: the rivet has to be drilled out shown in picture 3)
3) The cab. First you have to separate the metal part from the hard plastic part of the cab. In order to do this, there are six metal clips on the under part of the cab shown in picture 4 (note: The four metal clip are difficult to remove. I recommend cutting the center out and then unbending the clips...also great place to store batteries).
Step 2: The Rolling Chassis
The rolling chassis I made is convenient for this application because it makes it easier to attach the truck, as well as adjusting and centering the tire in the wheel well. It basically consists of two 3/4 in. x 96 in. x 0.050 in. Aluminum Thick Angle at 11 1/2 inches long. like shown in pic 1. Connected on each end to the angle are two Axial AXI30488 Locked Axle Set AX10, found on Amazon.com.
I braced the middle section for support with a left over scrap piece of aluminum with approximately 3 1/2x3" like seen in the picture 2. I've double the brace as a transmission mount for the Axial AXI30487 Locked Transmission Set for the AX10 Scorpion also found on Amazon.com (Note: "The transmission is mounted best suited for you. I recommend using a little loctite.) Coupled with the transmission is a AxialAX24007 55T Electric Motor, Axial AX30672 48DP 87T Spur Gear, Axial AX30569 48P 14T Steel Pinion, all found on Amazon.com.
Using the Traxxas 6852X 6852X Driveshaft Assembly Rear Slash 4x4 also at Amazon.com. Link the axel and transmission like shown in picture 3 (Note: I find these easier to use and modify then the axail ones).
I went with two waterproof servos, one Waterproof High Torque STD Metal Gear Digital Servo in front and a Traxxas 2075 Waterproof Servo (Revo. Summit, E-maxx, Slash Etc.. In rear shown in picture 4-5. I feel wheels are a preference, some like soft, wide narrow hard...etc so I say explore your own.
Step 3: Mounting and Assembly
Now that your chassis is ready, attaching the body should be a breeze. Just slide the body on top with the angle on the outside as shown in picture 1. (Note: Do not attach the truck body to the chassis until very end) Attach cab with bolt of your choice, you can either leave on the original hole or make a new one depending on your needs, like in picture 2.
I feel batteries are the hardest placement of all. Cutting the middle of the cab out and using zip ties to secure them worked best for me. (Note: Storing the batteries where I placed mine does make it front heavy when there's no dirt in the truck bed.) I went with 2 Duracell Ultra 6V 3.3AH AGM Battery DURA6-1.3F (as shown in picture 3-4), running them in series to make 12 volts.
I added the on/off switch to the top of the cab and hung the charge cord out the window for batteries (just in case they need to be charged) like shown in picture 5. I added a piece of angle behind the cab and directly behind that I added my Sabertooth Dual 12A Motor Driver for R/C also found on Amazon.com. So when the bed lowers, it's sitting slightly above it, as shown in picture 6.
I added my 100mm Firgelli acuator 100:1 gear ratio, (found on Firgelli's site) with the threaded rod on the side of the actual Tonka body(Note: I made the threaded rod long enough in case I want to add a second actuator (to increase usability and for dumping heavier loads) as shown in picture 7. (Note: I did not add the solar yet because the items are on order... But I will update when it's ready)
So there it is everyone, the Tonka Dump Truck fully converted. We hope this helps everyone get the creative juices and ideas flowing . Thanks for taking the time to read our instructable and we hope to see yours soon!