This is the thrilling second follow-up to the thrilling first part of our two-part series: From Barbie to Badass: The Make Lab Rats Transform a Power Wheels Jeep. If you want to read about some of the mistakes we made on the way, read that first. If you want to find out about the mistakes we made once we got there, read on.
I’ll begin this post at the last minute — the day before I left for Maker Faire, when the brakes, speed controller, and throttle still weren’t hooked up.
We’d planned on using a standard resistance driven speed controller, but that would cost money. And at that point, free was what our budget demanded. So we used one that lived in Brian’s garage. Unfortunately, it was voltage controlled. After much head scratching, he worked up a circuit to translate resistance from a pot to a voltage signal, reducing our two big problems to two little problems. Powering the circuit itself dropped the voltage, so it put out 11 out of 12 volts. So our nonexistent throttle still couldn’t reach top speed. After much more head scratching with crazy ideas, we just added in a button. The throttle would put out 0-11v, and the button connects directly to the battery to crank in 12 for high gear. Perfect for the throttle we still didn’t have. Fortunately, a call was answered just in the nick of time. Thank you once again Thunderstruck, more than I can say, for delivering a throttle mechanism with exactly the right spec we needed at the very last minute.
Working all day and packing for the Faire is exhausting. I left the lab around 9pm Wednesday night and fell asleep the moment I got home. The next morning I found a text Brian sent at midnight, telling me they were driving it around in the parking lot. Finally, the damn thing works.
The kart rode down in the back of Dan’s Jeep on Friday. MAKE Creative Director Jason Babler took it for a joyride indoors before the crowd arrived. A few lucky people tooled around in it that evening. For the most part though, people had an event to get ready for, and the car sat in the pit, waiting for the big debut.
Showtime. The first drive of the day is the time trials. Brian’s slotted into the car like a bobsledder, as if it was meant to fit him. Which, to be honest, it was. Helmet on, hands on the wheel, he waits in line patiently behind seasoned drivers. Cars that have had multiple revisions. Drivers who have practice racing something smaller than themselves with way too much power. The last car in front of him finishes its lap. Our pride and joy takes off. And very shortly thereafter, makes a noise like a harpooned gazelle and limps to a very inanimate stop.
The beast made it halfway through the first of two laps before I had to jump out from the pit and push. Suffice it to say, our qualifying time was a few minutes over the average. We beat it later, once we figured out the catastrophic dying thing. Turned out the drive sprocket wasn’t fully tightened down. Whoops.
We discovered shortly afterward that breaking the car in the first lap was only the start of our troubles. The turns were tighter than we’d planned for, and that made things tough. For one thing, any time a driver turned the wheel as far right as it could go, the throttle handle would lodge itself in the windshield, and the car would get stuck turning right at top speed. Rather than try to pass it off as a feature, we pulled off the windshield and left it behind. Which fixed the problem, though now our name was only displayed in back.
Another issue with those sharp turns was the wheel well. We put on big awesome wheels to make sure we’d have a big awesome car. What we hadn’t done was make sure the big awesome fenders didn’t get in the way during those rare occasions involving right turns. The wheels tore through the body each time. So we hacked a quick fix by stacking up some 9v batteries between the chassis and the body, giving us just enough clearance that the only time the driver had to worry about the tires was when their feet were in the way (which was pretty often; it’s a really small car).
Even with those injury-inducing bugs solved, the behemoth still had trouble around corners. We lacked the weight in front necessary to grip the turns. Putting the motor in back and batteries in the middle meant our legs were the heaviest things on the wheels. To our gratitude, the track organizers had the foresight to leave sandbags on barrels at various points around the track. Now, some may argue that the bags were meant to be part of the track itself, but those people weren’t the ones who needed some heft on their front end. Besides, shoving a bag under the hood worked beautifully. The only downside was that we hadn’t secured it so much as jammed it in the car, and it soon began to fall out just enough to tear itself a bit on the asphalt, spilling sand as we went. So if anyone following our car noticed themselves drifting a little bit in the turns, sorry. I’d like to offer my sincere apologies (and also a burrito, for good will).
You can see the bag hanging out in this video, posted by Genevieve from NIMBY.
Eventually we got the bugs mostly worked out, and saw the sort of performance we were hoping for all along. Brian drove it so well it’s boring to write about, so I’ll just show you the video instead. Sincere apologies to everyone who got tapped from behind.
As the Faire went on, we put the car through more trials. The most epic (read: car-destroying) one was the 75-minute-long endurance race. We went to our dedicated team of builders, friends, family, and volunteers to keep the thing on the track as long as it could stand. Our Web Developer Jake Spurlock and his brothers Josh and Ben took up the lion’s share of the endurance race. Jake did his part excellently by drifting the vehicle through the straights (which may or may not have been helped by the sand we dumped on the track earlier). His brother Josh helped excellently by crashing it into a couple of walls. And cars.
The most memorable race for me was the last race of the first day, where the Power Racing Series cars raced side-by-side against the Fun Bike Unicorn Club pedal cars (sorry again guys, we’re working on that pedal car). It was also not only the first race I’d personally been in, but also the first time I got behind the wheel since it could move under its own power. And since, in the interest of fairness, I didn’t want to make things too easy on myself, I put on a rat mask that cut off my peripheral vision. (Make Lab Rats, get it? We thought it was clever.) I won’t spoil how awesome I did — watch the video. I saved the best for last.
The thing about crashing a car into a wall is, it hurts. But immediately after, you stop caring, and you want to keep at it. Something about driving a go-kart awakens that childish fearlessness, where you run, bump into things, skin one appendage or another, and immediately want to keep going. And by the time the pedal-powered tow truck made it over, my helmet got straightened out, the car was flipped upright, the batteries were plugged back in (unintentional safety features FTW), and the eye holes in the rat mask were lined back up. I was ready to go. I finished the lap, and we finished the race dead last.
It was a good weekend, and we placed third overall. Not bad for our first go. After the Faire, we brought it back to the Lab, battered, bruised, and with a few scratches to hide from Uyen Cao (who was responsible for the awesome paint job). One less hood ornament, three wheels on the ground, and a slightly less working motor.
It’s a great thing to show off in the Lab. It takes up a ton of space and visitors get a kick out of seeing it. But we want it to do more. It’s meant to do more.
A couple weeks ago I heard Dan give it a little gentle persuading with a hammer, and it got a little love from a soldering iron. We can’t let it end now. Not without a trip to New York.
10 thoughts on “From Barbie to Badass II: The Make Lab Rats Race a Transformed Power Wheels Jeep”
Amazing and inspiring at the same time, i really liked the “nitro switch” idea! maybe when i build by own, i can use this. I will give you credit for this one :-)
Great writeup, Sam! High five!
Nice crash, it looked like it hurt!
It did! Very much so.
At least you had a great time.
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