The Marriott Chariot

You’re never too old for a go-kart.

When I was growing up, there were two things with which my mother forbade me ownership: BB guns and a go-kart. At some point my dad slipped a BB gun under the radar (I think my mom will find out about that when she reads this blog post) but the closest I ever came to owning a go-kart was the time my cousin Chris ran me over with his. Now, here I am at 32 years old. I happen to have my own fabrication shop and I’m looking for an excuse to buy the MIG welder I’ve always wanted. Then I read about the Power Racing Series.

Specifically, I stumbled across this when reading about Jamie Price’s Racing Powerwheels Jeep on Instructables. This looked like just the kind of ridiculous fun I wanted to have.

I happened to be looking for an accessory to accompany my absurd Marriott carpet camouflage costumes from DragonCon 2013. A tiny carpet-themed army Jeep capable of running 20+mph seemed perfect. My mind is a weird place.

So I had a very well-written DIY and an excuse to purchase a welder. I figured finding a derelict Power Wheels would be a snap. I searched Craigslist for a couple weeks but people were asking $75-$100 for plastic disasters covered in kiddie snot. A weekend circuit to 25 different yard sales also proved fruitless. As a last resort I took my search to social media, and that’s when I got a very excited email from Nathan. He sent me the following shot over instagram with the caption “is this okay????”

Nathan had spotted this once-red Jeep on the side of the road a couple years ago, and had dragged it home with plans to convert it into a tiny Jurassic Park themed vehicle. Over time it had given up its electronics, tires and a few mechanical components and the only thing left was the body. It was offered for the low, low price of free (!!!) and my search was finally over. Thanks, Nathan!

Time and the Georgia sun had not been kind to the old girl, and the decals that covered the body had hardened into some kind of impenetrable crust, partially fused into the plastic. The body was mostly pink, and in some places the polypropylene had started turning to dust. No matter, the vinyl wrap would take care of these small issues.The decals were removed with chisels, scrapers, and a generous helping of industrial strength adhesive remover.

I was missing the headlights, bumpers, some mounting hardware and hood hinges, but I felt confident in my fabrication abilities. First a few small metal hinges to make the hood functional again.

The dash was a huge bulging mass that would seriously impede me ever hoping to fit into the tiny chassis, so most of it had to go. I fed it through the bandsaw and all of the “gauges” went into the trash bin.

With a clean body I was able to take some photos of a few scrawled-on dimensions and create a rough digital model in SketchUp. I used this to plot out the frame and come up with chassis placement for the batteries, motor, steering and controllers. Initially I planned on using L-channel stock from old bedframes, similar to Jamie’s jeep.

Later on I found a steel supplier in Atlanta and ended up buying about 40 feet of 16ga square tube. It was actually cheaper than a thrift store bedframe! Plans changed at this point in favor of a slightly revised chassis.

Motor mounts were machined out of 3/16″ plate steel by my buddy Steven. I sent him these sketches to go off of and the final results (seen later) were awesome.

There’s a bunch of little standard parts that are available in the go-kart world that made fabrication of my chassis much, much simpler. Starting off, I purchased a set of steering spindles off eBay to handle the front end. These are super robust and very well built, too.

I had to carve away a lot of the body interior in order to get it to fit over the axles, but my plan was to retain as much as possible of the original Power Wheels. The under-seat tray, which used to hold the small motor and speed controller, got the heave-ho and I could finally see what the body would look like at my preferred “slammed” ride height. The wheels and tires here are made for a hand truck. They’re inexpensive, which is nice, but I shredded the tires in just one weekend and the bearings were shot, too. Probably not meant for the abuse I put them through.

Time to cut some steel! The large hexagonal opening in the middle allows me to keep the stock Power Wheels floor pan.

Tack, flip, tack, flip, tack, weld. It’s been nearly ten years since I did any serious amount of welding and my first few attempts looked like boiled anus. Luckily, I own an angle grinder.

It wasn’t long before I had a rolling chassis! The rear axle is a hollow bar with 5/8″ threaded rods sticking out of either end that serve as axle stubs. Both rear wheels spin freely and independently on two go-kart hubs with double flanges. One side holds the wheel, the other side holds the drive gear. (The drive gears did need to have new mounting holes drilled to match up with the studs on the hubs.)

The chassis passed the “stand on it and jump a little” test, so it was time to sort out the steering. I bought a tiny kid’s bike from a local thrift store and chopped it to bits, pirating the head tube and headset bearings along with bits of the fork. Ball joints and threaded rod were ordered from McMaster-Carr to round out the front end.

Here’s a close up of the steering pitman arm. I was starting to get the hang of welding again!

Power for the kart is supplied by two 12V, 30AH SLA batteries. Since they’re sealed, I was able to mount them in the chassis horizontally, lowering the center of gravity a bit more. The battery tray itself is a couple sections of L-channel I had left over from my vacuum former build. Bolts welded to the frame hold the tray in place, and this allows the batteries to be dropped out from underneath the chassis if they need to be swapped.

The beefy motor mounts ready for welding. One of these has a notch milled out of the side to clear the band brake on the left rear wheel.

Here’s the chassis at about 90% finished. You can see a bit more welding in the rear; the larger uprights are supports for the seat, while the thinner punched metal gives the plastic body a few places to mount.

A test fit of the body on the frame. For aesthetics, I chopped the windshield by about 3″. Sleek!

Ah, the Zippo test. Anyone who visits Volkswagen modding forums will be familiar with this. I’ve got about 5/8″ clearance between the ground and the bolt for the pitman arm. Plenty of space!

Here you can see how low the body sits inside the hexagonal frame opening.

And here’s the chassis complete! For testing, I dragged it off the loading dock near my shop and scooted around the lot, shopping-kart style. Never rubbed or scraped the ground, so I consider the test a success.

Components were removed in prep for paint, and the chassis was primed and finished with a few coats of flat black enamel. The smaller square tube parts are bumper mounts, and I’m very glad I added those in last-minute – if you notice in the gif at the beginning of this post, the rear bumper makes a great wheelie bar.

Frame complete, it was time to work on some aesthetics. You might ask why I chose to leave the under-hood area empty, when I could easily have added a third battery and ran 36V for more power and speed. Well, remember this is a vehicle made for DragonCon too… and under the hood is where the beer goes!

The front end was missing a bumper and bumper cover. The cover was vac formed from ABS, and a 1/4″ thick 1.5″ dia. ABS tube stood in on bumper duty.

For the seat, a few scraps of plywood were scrounged. Captive bolts mount to the frame using wingnuts, and the lower front section hinges upward to access the batteries and fuses.

Around back, I totally ripped off Jamie’s build and tossed a set of tail lights and a spare tire on the truck.

My dad found a set of LED flashlights at Harbor Freight that fit perfectly in the grille. These things are obnoxiously bright, even after adding three sets of diffused lenses. They’re powered off the main battery using a step down voltage regulator.

Here’s the frame during assembly. I worked by installing larger components first, then routing wires from each part to it’s corresponding part before trimming them to length. The small silver boxes here are the DC motor controllers, purchased super cheap from Amazon Prime! I bought three in case I end up frying one.

Velcro straps or a quick loop of electrical tape make fabricating a wiring harness much easier – just run some wire, tape it down, then continue until everything is in it’s proper place. There’s throttle, battery cut off, illumination, power and ground tied up in here. I need to go back in and wire up an additional on/off switch to the controllers though, in order to stay in compliance with the Power Racing Series rules.

Here’s the whole thing wired up and ready for a test drive! I wanted to make sure it all worked before wrapping the wires and making things look pretty. I hadn’t fully charged the batteries yet, but I tossed the seat on and took it out for a test drive in the parking lot. It was quick. For power I’ve got two 24V 500W scooter motors driving the rear wheels independently

Now, I work next door to a group of very cool guys that do art installation. These guys all think the project is awesome and they’re always coming over to see what new weird thing is being built in my shop. On the other side of my studio are a bunch of humorless knobs who do air conditioning installation, and one of them stood in the window of their space, arms crossed in disapproval. I bet he’s great at parties.

Here’s the wiring, looking much tidier with split loom and velcro straps keeping everything in place. I don’t know if neatness counts in this series (probably not) but in my opinion, proper wire care is all that separates mankind from the beasts.

I did mention the livery inspiration for this particular racing vehicle was to be DragonCon Marriott hotel carpet themed, right? Instead of paint, the full size file (12’x6′!) was printed to vehicle-wrap vinyl by my friend Jim at Atlanta Sign Services. The wrap process was actually done quite rapidly, and this vinyl conforms to tight curves wonderfully. It’s a good thing the cost of the vinyl isn’t counted against my car in the Power Racing Series, since it cost nearly half as much as all the mechanical bits!

Once the wrap was done, the edges were taped off and the underside painted with black truck bedliner. This stuff is super durable and actually sticks to the polypropylene body extremely well.

The full wrap, complete with matching seat!

I wasn’t keen on the glossy finish of the vinyl, so I sprayed the whole body with flat acrylic to knock the shine down. This helps it blend into the carpet much more convincingly.

The blinding lights were wired up to a switch on the the dash. I was hoping their position close the ground would make them less obnoxious… but it really didn’t.

Outside in the sun! This is after a few test laps and discovering the Harbor Freight tires are only “round” in the most general sense, but who cares! I finally have my go kart!

Here’s a view of the underside. Very compact and still fits 100% inside the stock power wheels chassis. Due to the the tires, it’s actually a little bit narrower and shorter than stock.

This thing was a huge hit at DragonCon. Some of the highlights include letting my friends drive laps on the 18th floor (what I’ve decided to call the DragonCon Grand Prix), doing a standing wheelie in the parade while the Red Power Ranger did a running forward flip over my car, drag racing the Turtles Van, and watching my wife thoroughly obliterate poor Luigi in a drag race Thursday night.

My first race is in Nashville on September 14th, and while I don’t think I have any chance of winning, I’ll definitely look great in last place.

For anyone looking to build their own kart, here’s a list of links where I purchased off-the-shelf parts:

Thanks for reading, and happy karting!

All of the products listed in this write up are the products that I used and can recommend. Some of them are provided as Amazon affiliate links, which help support Volpin Props.