Introduction: Electric Go Kart From Old Trash (On a Budget)
It all started when my father got a motor and a controller (not used yet) off a little electric truck some people were throwing away. Also, someone gave him an old go kart frame likely from the 70s. It had surprisingly little rust except for a seat on which someone poorly welded. However, it still was in "throw away" condition.
Throughout the instructable, I'll bold certain things I think will be most useful to know.
I would highly recommend doing projects like this with your children, as it helps them learn things that everyone should know. It breaks the chain of not doing anything for yourself and learning to do it through knowledge and error (and we had plenty of that).
Anyway, before I start, here's a video of the go kart I call the "Rat Buggy" in motion. Excuse the short length; it was meant to be a nice trip around the yard, but the camera didn't get the rest of it. I did as much as I could with what I had.
Also, realize that there are much better ways to do most of the stuff we did. We were mainly on a budget.
Here's a list of tools needed for this project:
-Bandsaw (for cutting metal and thick metal)
-Sawzall (for cutting metal the bandsaw can't get to. One or the other is fine.)
-Grinder (for grinding unneeded metal off and grinding metal to weld on down)
-Welder and welding hammer (Any welder works. I'm using a simple, wire-fed one)
-Sets of wrenches and sockets (for various tasks)
-Other small tools you might need, such as a hammer or clamps
Step 1: The Frame and Preparing It
This is the original frame that was given to us. The front end was entirely rusted together. It was originally going to be a gas engine, but electric was a personal preference.
First, I tried removing the steering wheel and shaft. The shaft was impossible to remove without welding, so I took a large wrench and banged the shaft and front end to loosen the rust off of it. I then took silicone spray (a lubricant), and sprayed every crack, moved everything to get it all in the cracks, and let it sit for several hours. This loosened it completely.
Here's a video.
Then, I removed the seat by unscrewing the bottom cushion of the modified seat and pulling most of the metal off since rust already got to that. One of the "arm rests" had to be cut off. For cutting metal, a sawzall or a band saw is an excellent choice. A hacksaw is okay , but it's tiring and time consuming.
Step 2: Preparing the Back End
Our next task was to extend the back end to accommodate the motor and battery.
The idea is to cut the frame and weld metal in between the gap.
First, we cut off the entire back end from directly behind where the seat was. We're using a hacksaw in the picture because he thought our sawzall was stolen. It was later found.
Then, we bought two square tubes (steel) and positioned them parallel to each other and ready to be welded.
Step 3: Welding the Back End
In order to weld properly, you need clean metal and no paint or rust. Therefore, I ground the metal on the frame down to where it was shiny. Otherwise, they probably wouldn't be very good welds.
First, we checked that the tubes were still parallel, then I made three large welds at the end of each tube. The right tube ended up being a bit crooked and the left ended up fine. Double check everything's right before welding. I wish I could bold that more. You don't want to have to grind all the welds off and redo the whole thing.
Then, we aligned the rear wheels and made three large welds there on each side also. However, in the back, we flipped it over and welded from the bottom also, grinding metal and making good welds.
The last thing to extend was the brake. I took the same idea for extending the whole thing and did it with a metal rod for the brake.
Note: I don't have pictures of the welding process because I was afraid it would damage the camera. Correct me if I'm wrong.
Step 4: Modifying the Motor
The motor used for this go kart came off of an old, little electric truck. It didn't have anything to chain to the wheel of the go kart. First, we searched high and low to no avail for a small pulley that would work with the motor.
We had a clutch for the go kart when it originally planned to be gas powered. However, electric motors don't need clutches, since they just... go. I took the outside part of the clutch (with the gear on it) and carefully welded it to the end of the motor, as in the pictures above. Sometimes, you will have to improvise. It can most likely be done.
Also, be careful when welding to not ruin anything. That is why there is aluminum foil around the clutch half. I wanted to save the original stuff on the motor for improvement (see last step for details).
Step 5: Setting the Motor Position
We bought roller link chain (35 pitch) and used a large metal bar (the one the motor is sitting on) and positioned the motor and bar to where the chain would be tight-ish. We then cut the metal bar to fit and welded it down.
To set it in place, we bought two sets of straps and tightened them on each end of the motor. The motor had so much torque, it ripped itself out of that and broke a weld on the large bar, so we crafted a piece of metal (much like the large bar) to bolt into a hole in the motor and weld to the frame along with the straps. That kept it in place.
Step 6: The Battery
The most expensive part of this build was the battery. It is specifically a deep cycle battery and will cost you around $100 for one. This type of battery lasts longer than a car battery for this purpose. Other things we had to buy for the battery included a kill switch, connections and thick wire.
We had to use some of the remaining large bar to make another bar and weld it directly behind the motor to keep the battery level. We then strapped it down in much the same way as the motor.
This motor works best with two batteries. However, we didn't have enough stuff to mount/wire the second battery.
Step 7: Wiring the Motor
Telling you the specifics of wiring the motor would be a bit useless, as other motors aren't necessarily wired the same way, but I can tell you the two outside wires are the power (and go through a switch I control), and the two insides, I believe, connect them.
We had the motor wired the way we thought the manual for the little truck thing said. It moved, but it was slow and was heating up the batteries quite a bit. I have this book , and it told us to wire it a different way, and when we did, it mostly ripped itself out of the straps and promptly threw the chain (this was fixed). When in doubt, research as much as you can. Research saved us from possible damage to the motor and batteries. Remember, this is all part of the trial and error fun!
It is directly wired to the battery, so there is no speed control yet (see last step for details).
Have a kill switch. I have two. The first kill switch is directly on the battery in case the second kill switch, the one in the front with me doesn't work. Basically, the one on the battery controls the battery and the one in the front controls the motor.
Step 8: Future Plans
This frame has had much abuse in its life. Due to time restraints of this contest, we have more plans for it.
This includes a complete re-build of the back end. The rear axle is bent and the chain is not happy about staying on. It will probably end up just being to cut out and replaced with a live axle and a new gear to turn both wheels. Also, we plan on redoing the weld of the half-clutch on the motor, as that is slightly off. We plan on putting the controller for the motor in to control speed and actually use the accelerator pedal. Other things include cleaning it up, mounting the front kill switch to the floor (it's not so we can paint it), putting larger wheels on it, mounting the second battery, putting reverse on it, and improving the mechanical advantage of the gears. Right now, the gear on the wheel is larger than the one on the motor. Roughly, every time the motor turns 4 times, the wheels turns once.
Also, I plan on painting it.