Ridiculously Huge RC Kart - $3,000 beast

[smooth90]

I’ve been working on this project over the past few months and its finally coming together. It all started with an idea to build a large scale “RC car”. I settled on a rather simple design. There is no suspension, I initially planned on independent front suspension and to have the rear move up and down. I made the body extremely strong through so there is no way this thing is going to bend. This is the second project I’ve done where I had the parts laser cut. Prior to this I made a large cart for my milling machine and it came out very well. I really like laser cut parts, when properly designed they fit together and weld up like a jig saw puzzle. I modeled and designed every part in the computer prior to building this and everything was perfect except for one or two minor measuring errors that I made which I was able to fix afterwards.

The kart that I’m building here can hit a top speed of about 45-50mph and is completely remote controlled. The total weight is about 350lbs and it has about 10-11hp because I heavily upgraded the engine (estimate, I haven’t tested this but I did lots of upgrades).

Is this a go kart? Not technically but I am welding a tow hitch on the back and them I’m going to weld a seat onto a garden kart like this one at the following link.

https://www.northerntool.com/shop/tools/product_200640327_200640327

The rider can then sit in the tow behind wagon with the remote control and go for a ridiculous ride (not sure about safety yet).

Specs:

Frame:

Base Plate:

Laser cut 10 gauge pickled and oiled steel

Square Frame:

2" 11 gauge steel

Look at the color and finish on the square tube! Thats stock straight from the steel distributor. I even asked them if it was painted! I've never seen such a smooth, dark, and consistent slag coating on hot rolled steel. It's honestly the best batch of steel tube I've purchased.

Welded on plates

Laser cut ¼” pickled and oiled steel

Brake:

MCP Hydraulic disc brake

The linear motor is a PA-04 motor, it is very fast at around 1.5” per second and 100lbs of force. It also has a built-in encoder for position control allowing the brake to be feathered remotely rather than just on/off. An encoder is much better than a potentiometer in terms of longevity, I didn’t know this but read up on it if you ever buy a linear motor, potentiometers start to fail after 5000+ cycles.

Steering:

I’m using a NEMA 34 stepper motor with over 1500oz in of holding torque to steer the wheels. I’m also using an 8 1/2" Thin Line Billet Rack & Pinion for the actual steering. The tie rods are not in yet, I ordered a whole bunch of rods and things to make sure I can come up with at least some sort of tie rod solution. I should have the wheels connected within the next week.

Here is the steering rack:

https://www.ebay.com/itm/8-1-2-Thin...ash=item2c68d04fbb:g:w~gAAOSw8x1ZepFW&vxp=mtr

Engine:

• 
  
  
  
  [*]Harbor Freight Predator 212CC Hemi
  
  [*]Billet Flywheel
  
  [*]Billet Connector Rod
  
  [*]New Stainless Valves
  
  [*]32Lb springs
  
  [*]1:2 ratio rockers
  
  [*]Upgraded valve cover (cosmetic)
  
  [*]Mikuni fuel pump
  
  [*]Mikuni VM 22 Carburetor (not installed yet)
  
  [*]Upgraded Air Filter
  
  [*]Upgraded Exhaust
  
  [*]Oil sensor completely removed
  
  [*]Governor completely removed (hole threaded and used to run fuel pump)
  
  [*]Stock cam (I have one to go up to 8400rpm, but it won’t fit)
  
  [*]Torque converter (basic off brand model, not comet brand)
  

I am still in the process of building this, it’s a pretty complicated setup. I may have to switch to a 3D Motorsport manual clutch and have a linear motor or servo actuate it. That will probably be a much better solution.


As of 11/10/17:

I tested it out on the jack stands and the drive system is working perfectly. The chain is nice and tight and the brake is lined up perfectly just like the 3d model so I’m really happy with how everything has worked out so far.

To Do:

I just ordered four large project enclosures, two are weatherproof and another two are metal and pretty much weatherproof but not sealed completely.

This is the main enclosure that I’ll be using:

https://www.ebay.com/itm/Altelix-14...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

It has two 100mm fan ports which is fantastic. This way I can fit the large stepper motor driver inside the box and keep it cool. It is definitely going to get hot when its in there.
Later on I’ll build a roll cage for and plate it with thin aluminum sheets, then I’ll paint it in matte black so it looks really nice and doesn’t rust.

Here are the build pictures, enjoy! Please let me know what you think!

 

[smooth90]

Additional Build Pictures

[/url]

 

[Randy H]

super cool man.

 

[smooth90]

Question/Comments

If anyone has questions or comments I'd be glad to hear them. This project was pretty challenging so I'm pretty enthusiastic about it. I think it'll be ready for a road test within 10 days.

The initial electronics that I'm going to put in it will be dead simple. I'm going to use a bunch of Arduino Pro Mini's and a cheap radio receiver from Hobbyking. This way each Arduino deals with just one task (brake, throttle, steering, master control). I'll also have a totally separate system with some very powerful long-range radios that will act as an emergency override. This way if it goes haywire I can push a big emergency stop button (I'm building a remote control panel box) and the secondary system will cut the engine and automatically force the brake to completely engage.

I think for a normal RC car such a safety system isn't really required but this thing is 350lbs and can easily reach 45-50mph, maybe more. I think the secondary safety system is critical for this, I might even add a third system as well that's totally independent (separate battery, radio etc..).

 

[smooth90]

Drive System Test Video

Here is a youtube video of me testing out the drive system.

At 1min in the engine starts (I had to pull the starter a bunch of times to get the fuel pumping, the engine hadn't been started in months)

At 2:10min I start throttling the engine and the wheels start spinning.

The wheels don't stop spinning after that even at idle and I think that's because it's on the jack stands and there's no friction stopping the wheels from turning, or the idle speed is too high. Once I get the new carb this will be easy to fix, the stock carb is a piece of crap.

 

[tgus3]

Really cool build I like rc's and this is really neat.Keep us updated.

 

[Kartorbust]

Kind of reminds me of a battle bot chassis from many years ago.

 

[MTNSleder]

Can I ride on it?

 

[smooth90]

Can I ride on it?

Yea definitely I was thinking of adding a seat mount in the center so a one could be bolted on and removed as needed. I'm really looking toward the tow behind approach for riding this kart. I want to create a really low profile roll cage for this that's only slightly higher than the engine so tow behind riding will allow this. This way I can plate the whole roll cage in thin aluminum plate and have it look like some sort of batmobile battle bot looking thing. I know it looks like there's potential space for a rider but pretty soon all that empty space is going to be filled with plastic and metal enclosures (that will be filled with batteries and electronics).

I started messing with the electronics today. I got the transmitter/receiver up and running. The throttle servo is hooked up to the transmitter trigger now so I'm pretty excited to test it out soon.

 

[MTNSleder]

What happens when a computer hacker hacks your kart and steals it?

 

[Kartorbust]

What happens when a computer hacker hacks your kart and steals it?

Now you're just being ridiculous. It's highly doubtful that could even happen. Let alone they would have to manually pull start it and these engines are not exactly quiet, so they would not be able to do it without making a scene.

 

[MTNSleder]

Now you're just being ridiculous. It's highly doubtful that could even happen. Let alone they would have to manually pull start it and these engines are not exactly quiet, so they would not be able to do it without making a scene.

Just asking questions

 

[smooth90]

What happens when a computer hacker hacks your kart and steals it?

If someone wanted to hack into this I guess it might be possible in principle but its something I absolutely think will %99.99999 of the time never happen. It's not connected to the internet which is where basically all hacking is done from so if you wanted to hack this you'd have to be very local (within a couple miles, maybe 5 with big antennas/transmit power) and match all of the hardware/frequencies I'm using. On top of that a hacker would have to guide it somehow to "steal" it and if there's no camera onboard (not in my initial design) they would have to be in visible range to steal it which is really obvious, that or have a drone overhead to guide it which is even more ridiculous. Even if I add a camera you would have to match the camera frequency in addition to hacking the control system. There’s just so many things someone would have to do to hack this that its just so impractical. I think a regular go kart is at a much higher risk of being stolen since it could just be started up and easily driven away.

The first V1 electronics are not the best out there. I'm using cheap equipment to prove that the whole system works before I invest more into it. The second generation V2 electronics are going to be way over the top. I'm going to put an RTK GPS system on it that's accurate to 1 centimeter, with this I can plot out a course of my neighborhood and have it do laps at night all on its own if I wanted it to. I'll also be upgrading the radio system with much higher end radios that include encrypted communication by default (makes hacking the signal/data basically impossible). The entire control system will be done through encrypted communications and there will be redundancies built in should one fail.

 

[karte_m0lim]

what if hacker drives a truck?

 

[MTNSleder]

If someone wanted to hack into this I guess it might be possible in principle but its something I absolutely think will %99.99999 of the time never happen. It's not connected to the internet which is where basically all hacking is done from so if you wanted to hack this you'd have to be very local (within a couple miles, maybe 5 with big antennas/transmit power) and match all of the hardware/frequencies I'm using. On top of that a hacker would have to guide it somehow to "steal" it and if there's no camera onboard (not in my initial design) they would have to be in visible range to steal it which is really obvious, that or have a drone overhead to guide it which is even more ridiculous. Even if I add a camera you would have to match the camera frequency in addition to hacking the control system. There’s just so many things someone would have to do to hack this that its just so impractical. I think a regular go kart is at a much higher risk of being stolen since it could just be started up and easily driven away.

The first V1 electronics are not the best out there. I'm using cheap equipment to prove that the whole system works before I invest more into it. The second generation V2 electronics are going to be way over the top. I'm going to put an RTK GPS system on it that's accurate to 1 centimeter, with this I can plot out a course of my neighborhood and have it do laps at night all on its own if I wanted it to. I'll also be upgrading the radio system with much higher end radios that include encrypted communication by default (makes hacking the signal/data basically impossible). The entire control system will be done through encrypted communications and there will be redundancies built in should one fail.

Well I was just thinking of getting a remote on the same frequency and drive it away I've had that happen before..

 

[itsid]

Well I was just thinking of getting a remote on the same frequency and drive it away I've had that happen before..

..........
The rider can then sit in the tow behind wagon with the remote control and go for a ridiculous ride (not sure about safety yet).
.........

would be quite a sight if the thief not only steals the kart,
but the owner as well

but true.. frequency alone is not good enough security on expensive RCs..
but encrypted data protocol and/or GPS trackers are
(thankfully that costs about nothing nowadays )

'sid

 

[MTNSleder]

would be quite a sight if the thief not only steals the kart,
but the owner as well

Put your Winter jacket on smooth90 Canada's cold!

That's for when I hijack you and your kart

 

[kevbo22]

Well ****, this things cool! I'll be following it to see it in completed form.

 

[landuse]

This is an awesome build!!!

Just one question though....I see that the frame is just tack welded together. Are you not concerned about that?

 

[ezcome-ezgo]

This is cool. The turning radius is roughly Kansas?