Archive for the ‘building a go kart frame’ Category

Brakes. Who needs ’em. Well, come to think of it we do…especially now that we’ve completely removed the coaster brake on our drive wheel. I know, I know, you’re thinking “Well, why did you go and do that? You had such a nice solution.“A couple of reasons.
First, as you know we needed to remount the rear wheels. The simple offset block of wood we had just wasn’t cutting it, and second was an observation I made with our coaster brake setup. You see I realized that no matter what I did, since we had move the coaster brake bracket to the opposite side of where the actual clutch mechanism for the brake itself exists, well the brake would never really work or at least work well. In fact after a few dry runs I realized that the setup we had would actually inhibit the wheel to gradually work loose each time you applied the brakes! Either that or the wheel would gradually lock up. Either way, as Luke would say “That’s bad.”.

To solve my problem with the brakes I just decided to simply gut the wheel hubs and remove the brakes altogether. By doing this I effectively made the hub a “free-wheel” (where you can pedal backwards, coasting, but engage the sprocket going forward).

After doing a fair amount of research to determine whether or not I could actually make the coaster brakes do what I wanted them to do (I even went so far as to say please) it was simply easiest to not use the coaster brake at all but rather build a hand brake system. We’ll get to actually building the brakes  on another day, first we needed to settle the wheel hubs and mount them. To solve the problem with the mounting I opted to completely eliminate the brake and axle assembly from each rear wheel. In lieu of the factory axle on each wheel we would use a single solid axle that would go through the frame, and through each wheel.

Drilling for our new rear axle.

I headed to Home Depot and picked up a 36″ length of 3/8″ steel rod. I decided I would run a single axle through the frame, and mount each wheel onto the axle. This would insure that the wheels were not only parallel but would give them that much extra strength to hold the riders weight.

First we needed to determine exactly where to put the axle. I realized after some earlier test rides that the wheels were a bit too far forward in that a heavier rider would have just enough weight behind the rear wheels that the front wheels would just barely come off the ground. Based on this I decided to move them back a good 2″. This will require we build a longer chain, but that won’t be too big of a deal.

Once we had our holes drilled we needed to determine exactly how we would hold the axle in place. I realized that the pipe floor flanges we had used earlier were perfect in that the axle would fit just right through the threaded hole.

Good ole pipe flanges. They've proven quite useful in this project.

With our axle holes drilled we positioned our pipe flanges on each side, marked the holes, and drilled mounting points.

Next with our flanges drilled and mounted we set our sights on the axle itself. We placed the rod into our bench vice and proceeded to thread approximately 5″ on one end. We used a die that was the same thread as that of our wheel axles, which will allow us to reuse all of the threaded pieces that came with the wheel. With each step I took here I constantly would ask myself “Now, why didn’t I do this to begin with ?”. The fact that I was being barraged with questions like “Dad, when is this going to be done?” and “Dad, can I ride the go kart now?” didn’t help either.

The threading process went quite smoothly with the boys chipping in here and there though they always seemed to have one ear cocked towards the street awaiting the now almost daily ice-cream-man pilgrimage.

Threading our axle to match the old ones so we can reuse the wheel hardware.

We threaded one side and slid our drive wheel into place on the axle. I intentionally only threaded the one side so that we could slide the axle into place to get a measurement of how much to cut off before we threaded the other side.

I carried the wheel and axle assembly over to our kart and slid the axle into the frame. Next I went to tighten the outer wheel nut in place and realized the outer wheel ball bearings had fallen out of the wheel somewhere during the 20′ journey I had just taken across the garage. I just had them… didn’t I? They’d turn up eventually I figured so I continued with the rough assembly to get a measurement of our axle.

Axle with one wheel mounted and one wheel hub removed.

I placed the axle into the frame, all the way through, and out the other side. We had at least 8″ of excess coming on the other side. I positioned the wheel approximately where it would be and measured how much length of axle it used. I then used that measurement on the other side and made a mark to indicate where we would cut off the excess length.

Next we pulled the axle and wheel back out of the frame and cut off the end we had just marked. With our axle now the proper length we then threaded the other side to prepare to mount this second wheel. I went ahead and repacked the wheel bearings of the second wheel since we will be assembling that wheel onto the axle next. While I was doing this I realized that my trusty assistant had disappeared into the house. I knew he had greasy hands so figured I’d try to catch him before my wife did. New couches + greasy hands =  bad news for sure.

I found him in the hall bathroom…washing the missing ball bearings in the sink. At least we found them, and now they were now clean, cleaned with hand soap no less.

Both wheels mounted with our axle through the frame.

With all of our hardware now present and accounted for we pressed on. I positioned the axle into place, reassembled the primary wheel with it’s found bearings, and attached our second wheel. The wheels looked nice and straight and strong to boot.

With the axle in place next we threaded 1/4″  bolts through each of the four holes in our pipe flanges. These not only provided a nice solid hole for the axle to go through, but also provided a bit of extra strength to hold it all in place with the four bolts. Solid wheels, solid axle, it was all looking quite good.

By this time it was about 7:00 pm. With the weather warm and longer days the boys were all playing outside. I asked one of them if he wanted to take a little test drive with the rear wheels remounted. Not only did he reply with; “Yeah!!!” but he proceeded to announce to every child on the street that their go kart was finished. Of course it wasn’t quite. I knew very well where this was headed. Within minutes a steady stream of children ranging from two to twelve were suddenly lined up in my driveway to take a spin with each screaming “I’m first! I’m first!”. Of course the chain wasn’t on yet so I found myself acting as an amusement park ride operator, pushing each child down the street only to turn around and do it again with the next in line. The smile on their faces and shouts of “This is awesome!” was well worth the lower back pain that I was later greeted with. After I was about half way through the line of children my wife opened the front door, smiled, and yelled: “Hey, is that an airplane?”.

Everyone’s a critic.

Next up our fancy new brakes…

When I was in high school I took an automotive bodywork class. The course included repairing dents, painting cars, welding, playing with a plasma cutter, etc.  Great stuff.  It was a good class and I learned a lot, but one of the most vivid things I remember is the teacher telling us that painting anything, cars or otherwise, is 80% prep work. You can have the most expensive paint, the best gun, a great environment to paint with, but if you don’t prepare it’s all worthless. I remember this as well as the fact that the teacher inexplicably drove his truck through the gate of the body shop yard, but that’s a different story.

A quick break before we dive into our prepwork.

With our kart clearly we’re not painting a full size car, but I did feel we needed to do a fair amount of prep work before we even could consider applying any color to our kart. The first thing we needed to do was remove the wheels, exhaust, etc. It was a bit sad in a way, to have put so much effort to getting the exhaust just right, the wheels in place, the steering linkage, etc. only to say “OK guys, now let’s take it all apart.” Amazingly the boys were not only fine with this, but they really dug in and helped… no really… seriously… what you don’t believe me?

Before we began they asked if they could sit in it one more time before we took most of the pieces off. Oh, and of course, they asked if they could have an Otter Pop as well.

With our Otter Pop break out of the way they got out their tools and went to work. First we put the kart up on our saw horses. The height was just perfect for the boys with the work right at eye level. You could almost say it was their car lift of sorts.  Next I told them we first needed to remove the front wheels.

We started with removal of the front wheels.

I had them each remove one wheel, pull it off and set it aside.  With the front wheels off we then moved to the back. With the wheels off I asked them to place the washer and nut back onto the wheel axle so we wouldn’t lose them. One of the boy’s asked me “What did you call that Dad?”, I replied “What, you mean this washer?”.

He then asked me in a very matter-of-fact way “Why do they call it a washer, it’s not cleaning anything?”. You know he did have a good point. Leave it to a six year old to point out the obvious.

The rear wheels were somewhat of a two-man, or rather two-boy, job in that one of them had to hold a nut that ran through the frame while the other loosened it from the outside.

While they were doing this I was reminded of working in various repair shops years ago, and being under a car that was on the lift at roughly the same level. I was working at a local Montgomery Wards Auto Center.

I had just started working at this shop a day or so before and hadn’t had a chance to bring my own tools into the shop, so my boss graciously let me borrow his. He had a brand new Snap On roll-away. This was the big-daddy of tool boxes. Now things of this level tool box are commonplace, but this was roughly 25 years ago. This tool box had everything, including a built in stereo.

I had a small, front-wheel drive, car on a hoist in front of this tool box. I lifted the hoist, raising the car where the wheels were at my eye level. I then proceeded to remove the wheels, starting with the rear. Let me remind you we had a front wheel drive car,  in the air… with no rear wheels. You can probably guess where this is headed.

Once I removed the second rear wheel I immediately realized I had the car a bit too far forward on the hoist… and it began to take a nose dive into my boss’ tool box. Yes, I soiled my pants, but only after I jumped on the rear bumper as it shot into the air to level the car.

Luckily it didn’t slide off the hoist, and my boss was never to the wiser. For at least a week after that experience I never lifted a car higher than 12″ off the ground on the hoist.  Word of advice… don’t do that.

A bit of wood putty here and there never hurt anyone.

With our wheels all removed from the kart we then removed the exhaust. With this stuff out of the way we could sand all our rough spots and fill in the screw holes with a bit of wood putty. I say a “bit” but one could go so far as to say I applied it quite liberally.

Where we used the most putty was where I wanted to make as smooth a transition as possible to our moulding on the tail. This process required adding putty, drying, sanding, and repeating for what seemed like days. The weather was a bit cool so the putty didn’t want to dry as fast as it otherwise would have.

After some time sanding we were all covered in saw dust and powder from the dried wood putty. Without any suggestion the boys ran off and found some safety goggles to help them with the dust in their eyes. I was really surprised to see how much they were into our progress, it was great to see.

Once we sanded off all the rough edges we took some 3M painters tape and covered the steering spindles and the top of the steering column.  Had I had the room and flexibility I would have preferred to use spray paint, but we went ahead with a foam brush and applied a nice couple of light coats of Kilz exterior primer/sealer to the entire kart.

A white ghost of a go kart. Thank you iPhone for the lackluster lighting.

The wood was all ready to have the primer applied. As for the steel part I wasn’t sure if it would stick. To be sure I went ahead and roughed it up with some really fine sand paper. The kart was really looking ugly at this point, but I knew it would work out in the end. Or at least I hoped so.

We let the primer dry for a day or so, then applied a second coat just for good measure. I’m beginning to see the result of our hard work.  At this point I realized that in pretty short order I’d have to decide on a color for this thing.

Since day one I’ve been on the fence as to whether I should go traditional, “Bugatti Blue”, or something a bit different but with the same vintage feel.  Decisions, decisions.

Until the next afternoon I can squeeze in some progress…

Anyone who has caught pictures or video of racing events from the early 20th century is probably aware that the engines in those cars were pushed to the max. Although they weren’t fast (at least as compared to today’s cars), they were driven all out as if they were. Where cars today have computer controlled modules and the like to push the horsepower up, many of these vintage cars had motors similar to typical passenger cars. One big difference was that these cars were stripped of unnecessary weight, and the motors were pushed to their limits. And with these limits came heat…and lots of it.

The inspiration for our go kart. Note the louvered hood.

During this period it was commonplace to cut louvers into the sides of the engine compartments in these cars for ventilation. I’m not sure if it made that much of a difference but regardless, it sure looked cool, almost resembling the gills of a shark.

If you’ve been following our project here you’ll know that our kart won’t be having an engine at all, however in the interest of looking like it does we will be installing some of these ventilation louvers.

I thought quite a bit about how best to go about this step. I considered cutting a rectangle out on each side and manufacturing wooden slots, or to place a hinged piece of wood that would allow access to the steering linkage. While both of the ideas are very doable, they would just be overly complex.

You too can have instant louvers for the small price of $1.49 each.

Our plans note to use a large heating type vent that I thought sounded heavy and may just look funny. One day while out running errands I dropped by the local Lowe’s. As it turned out they had tin panels, nice and thin, with louvers cut in them. These are panels that one would use say to provide ventilation in an attic or maybe on the top of a garage wall. They’re similar to what the plans noted, but since the plans were roughly twenty years old, these were probably just an updated version of what they were suggesting. The louvers were nice and light and relatively small.

The only drawback was that these had the louvers facing down, and I would have preferred them facing back but I can live with it.  Not only did these have the look I was wanting but the price was right as well. For a whopping $1.49 each our kart was going to be all set.

Before I dove into mounting the louvers I decided that I would make some changes to the top body panel. The plywood was plenty strong, and fit fine. The problem was rather that I realized that after raising the height of the dash (and steering wheel) there was a gap revealed where the boys could stick their hand inside.

Our shortened body top to prevent random objects from getting stuck.

I wasn’t so worried about getting a hand stuck but rather knew for sure that someone would drop a Hot Wheel, a baseball, or heck maybe a Popsicle in there and we couldn’t have that stuff stuck inside right? Although come to think of it wouldn’t be any different than my car. To this day there is a Hot Wheel that I can’t find in the back of my car that I’m reminded of every time I make a right hand turn as it rolls from one side to the other. When my boys grow up and have a family of their own I’ve secretly sworn to myself that I would hide various rolling toys in their cars as some sort of twisted revenge. When I ride with them I’ll then pretend to not hear a thing… it will be just fantastic.

To address this little issue I removed the body panel top, and cut it about 4 inches shorter, on the end closest to the grill. This now leave an open space so that anything that may happen to find it’s way up there will simply roll out the other side. I cut it down and refastened it to the body side rails with 4, 1.25″ wood screws.

With this piece now back in place the body now has the strength to stay rigid while the louver panels are screwed in. I measured back from the grill about 4″ and down from the body top about 3″ and held the louver panel into place. This left about 4″ of space between the bottom of the louvers and the frame rails. It’s in this space that I intend to mount the exhaust pipe so that should be fine.

The panels have six screw holes, each of which I marked with a pencil. I set the panels aside and drilled small pilot holes into the body.

Our engine well ventilated.

Once the holes were all drilled I held our panels back up and ran each of the screws into place. I suppose using pop rivets would look better for mounting these, but I don’t happen to have a rivet gun. Besides using a screw would make it easier to remove them if I wanted or needed to later. In the end the screws, and louvers themselves, will all be painted so it won’t be too noticeable anyway.

There we go, some good eye candy for our kart. Next will either be our faux exhaust pipe, or the aluminum body top, I’m not sure which but probably the exhaust since having access from the top will make things a bit easier.

Next we’ll be tackling the overall body of the kart. As with anything that moves, the shape of the body is ever so important.

If we look at Ferraris, Porsches, as well as Bugattis, etc. they are all distinctive in their own way. They all have great visual appeal. Sporty, aggressive, each is really just a work of art. In contrast you can look at say a Prius, which one could say is a good car, but on the visual side really isn’t much to write home about. In fact I’d go so far as to say it’s nothing at all to write home about. I know, I know, environment, green, granola, blah blah blah. I’m talking strictly aesthetics. You could also say that the Prius costs a fraction of the price of cars that are much better looking. This is very true, but why should price have any bearing on how nice a car looks?

I think there is an unwritten rule that for a car to be more affordable and environmentally sound it must also be relatively unattractive, or put another way “It has a nice personality”.

I can only imagine a college intern working in Detroit comes up with a great car. It’s plenty fast, reliable, looks great, is reasonably priced and get’s 100mpg. He thinks he’s about to give his career a great kick start when he presents his project to upper management, only to be told the car he’s designed is too attractive. Hey, could happen and probably has.

So now let’s look at the go kart scene. You can definitely see the relationship to it’s larger cousins. There are a number of commercially available vehicles today that one could consider a go kart for kids. I’m not talking about racing karts, but rather ones that are just good fun for a variety of ages. You’ve got the various Power Wheels Jeeps at Toys R Us as well as some interesting stuff from Razor. Aesthetically the Jeeps are cute, but not exactly sporty. The Razor karts (if you could call them that) have received great reviews but don’t look like much. They look like the bottom of a shopping cart with an electric motor. I guess you could think of them as the Arial Atom of kids cars. Not much to look at, but one heck of a ride. As with my Detroit reference, why the rule of adding advancements to the car at the expense of looks? Of course safety is always an issue, but where possible these things should all have looks plus fun.

It just seems that kids are destined to either have a turtle made of plastic that dies a slow death in the corner of the garage, or something a bit more fun that looks like it should be driven on the moon. We already have far too many pets at my house, and if my kids are driving something that looks like it should be on the moon I sincerely hope they’ve become astronauts. Our goal here is to make something that both looks good and is fun to drive.

Back to the project at hand… our kart now has the frame all set in place.

Grill shape cut out and ready for mounting.

Grill shape cut out and ready for mounting.

According to our plans the next step is to cut out and mount the grill, and follow that up with the body panels. I cut out the overall shape, leaving approximately 1/4″ gap on both sides where the body panels will mount. I also cut a slight notch on each side so that the body panels will mount flush against the grill.

Next I placed the grill into position and attached it to the back of the upper and lower control arms with 2″ wood screws. You can see in this shot I also used some scrap 1/4″ plywood pieces to make sure I had the grill centered.

Note that before I attached it I drilled small pilot holes into the grill and into the control arms. Before setting the screws I also ran them through a bar of soap to help prevent the wood from splitting… or as I told the boys “Here, let’s give these screws a bath.”.

Both panels cut out with notches to account for the rear cross member as well as the rear wheel mounts.

Both panels cut out with notches to account for the rear cross member as well as the rear wheel mounts.

After mounting the grill I drew out the template for the body and cut one out. After I cut one side I used it as a guide, and drew and cut out the other. Once they were cut out I was starting to get an idea of the position of the rider, etc. I was a bit worried if the kart would just be too small for my oldest son. I really won’t know until I get the seat in place so for now I’ll just have to wait and see.

Before I could permanently mount the body panels I needed to consider the boat tail. This part of the body is the pièce de résistance, the icing on the cake, well you get the idea.

I’m not what one would call a woodworker by trade. So when the plans referred to steps like “Now, add the kerf lines into the panels at the following locations…” I kind of went “ummmmmmm. Now what.” I thought to myself, Hey, you’re a resourceful guy. My father-in-law has my table saw so I figured it was time to get busy with my trusty $59.00 Skil saw. I’d used it primarily for everything up to this point (except where I used a jig saw to cut corners, etc) but wasn’t sure I could use it to cut these kerf lines. To this point it has been used to cut from point A to point B and not cut any fingers in between.

Practice kerf lines cut onto some scrap.

Practice kerf lines cut onto some scrap.

To see if these types of cuts were even feasible I tried a few cuts on some scrap plywood that was the same thickness as the body panels. Surprisingly the saw blade was able to raised high enough that it cut about 50% of the way through the panel, allowing it to bend for the boat tail. Awesome.

Now to make the same cuts at the right spots on the actual body panels before I mount them onto the frame. On the inside of the panels I drew my cut locations starting at just behind the seat cut out, and every 1″ for 8″ back.

As I had with the scrap piece, I then ran my Skil saw over each line until I had cut them all. You’d think I hit the lottery I was so pleased with myself. The result was perfect. As the plans note, once these cuts are made the panels are really fragile so you need to be careful when moving them around. With my kerf lines cut I could then mount the panels to the frame.

I set the panels inside the frame, sliding them into the 1/4″ gaps I had left on both sides of the grill. The panels fit perfectly into the upper notches of the grill and the notches fit perfect in the rear as well as around the wheel mounts.

Cut body panels set in place on the frame.

Cut body panels set in place on the frame.

You can see in the shot the kerf lines and get an idea as to how the body will be bent inwards to form the rear boat tail.

With the body all cut I then drilled pilot holes about every 5″ down the length of the body on the inside, into the frame. After that I drove 1″ wood screws into the body panel and halfway into the frame rails. The nice thing about mounting the screws from the inside is that there aren’t any screws visible on the outside of the frame rail. Not a big deal, but one less thing I need to clean up prior to painting.

Now that we had a body starting to take shape one of the boys came over and wanted to sit in it. He took a seat (which amounted to sitting on the ground in the center) and I asked him what he thought.

He thought for a minute and said “Dad, what are those things called that dead people are put in the ground in? A coffin?”

I smiled at him. He then continued, “Dad, can I have an Otter Pop”.

Next we’ll give this rear end a little shape.

When we last saw our action hero he had set up the frame, king pins (spindles) and mounted the upper and lower control arms in place. The plans called for building our own 16″ wheels out of plywood planks and mounting bicycle tires onto them. The end result would look really nice and definitely keep the similarities of the wheels of Bugatti in it’s day, but to put it lightly, what a pain! Not to mention I would suspect they would add a lot of weight to the kart.

As with the MG kart project, I too was going to use some bicycle wheels. In that case he used four front bicycle wheels. As luck would have it my oldest son recently grew out of a bike, a Spiderman bike to be precise, that had 16″ wheels. Perfect. I now had half of the wheels I needed. Now to find two more, or rather two more that matched. You see these weren’t simply your basic chrome spoked wheels, these were the masked super hero special wheels. These had red spokes and a black rim so I couldn’t pick up just any set of wheels, that would be blasphemy!

I tried turning to friends and family to see if by chance anyone had the same bike sitting around. You’d think my chances were slim to none, but I just happen to know that this bike was available at Costco a few years back, and I also know that Santa shops there on occasion.

The responses ranged from “No, but I have a Barbie bike you can have!” to “I have wheels but they are purple, they’re yours if you want to come get ’em.” Purple wheels, next to my existing Spiderman wheels!? That would be perfect…if I were making a stage prop for an episode of HR Puff N Stuff.

I turned my attention to the net, specifically Craigslist. I found three bikes for sale right off the bat. In fact I came across one for a mere $5.00. Since it was located a couple hours away, I asked a friend who lived nearby to go pick it up. For only $5.00 I now had an exact duplicate of our Spiderman bike. To add a bit of high tech mystery to this project we could refer to it as a clone I suppose. I told my wife about the good fortune. She seemed genuinely happy, but I suspect it was do more to the selling price rather than the find. “What are you going to do with this when you’re done?” she asked. “Getting it finished isn’t the point, it’s the journey much more than the destination!” I said. Getting all deep and philosophical I figure would be better than a simple “Who cares, it will be cool!“.

The disassembly begins.

A sacrifice to the Go Kart Gods.

Next I started to disassemble the bikes. The boys saw this and went ballistic,”Dad! I wanted to ride that!” I diffused the situation by saying I was only borrowing the wheels (not to mention the chain, and sprocket). I replied with “Don’t worry, if you want to ride your old bike again we can just put take them off your go kart, and put them back on your bike.” That’s what I said, but what I was thinking was more like “This go kart will be so cool you’ll forget your Spiderman bike ever existed!“. Well that settled that.

I wanted to go with bicycle wheels for a number of reasons; simplicity, availability, leverage of using the coaster brake, and the sprocket. I’ll get to the sprocket later. For now let’s look at exactly what it’s going to take to use bike wheels since it’s not as straightforward as one would hope.

Back over on the kart, I started mounting the front wheels. I had previously drilled the front spindle holes to accommodate the axles.

In the center you can see no threads. Extending the threads will give more space to move the wheel position.

In the center you can see no threads. Extending the threads will give more space to move the wheel position.

I went to put the first wheel in place only to discover that the axle wasn’t quite long enough to go through the spindle, through the other side and still have room for a lock nut and washer on the other side. I suppose I could replace the axle with simply a longer bolt right? Theoretically this would work just fine, but I wouldn’t be able to use the bearing retainer nuts which are slightly rounded specifically to hold the bearings in place. This would work if I could find a 5″-6″ 8mmX105 axle which as it turns out isn’t as easy as you would hope. I hit the hardware stores nearby and had no luck. Thank goodness the US completely adopted the metric system as it has.

On closer inspection it wasn’t that the axle wasn’t long enough, it was actually plenty long, it was that the wheel needed to be shifted in one direction a half inch or so. Easy right? Simply thread the bolts further in on one side, and further out on the other, and more of the axle would be available to go through the spindle. Not so fast.

It turns out that the axles for the front wheels are not threaded all the way across, but have approximately 2″ in the middle without threads. This means that if you wanted to shift the position one way or the other you can’t go very far. My solution? Simply take an 8mm die and extend the threads further down the axle. Run the die onto one end (doesn’t really matter which) of the axle, and go all the way down into the center. This can be quite a pain, but by moving back and forth slowly, you can add a few more threads which is all you’ll need. Occasionally spray some WD40 (or similar) lubricant and stop every so often. The die and threads will be extremely hot and can easily snap so take your time.

Offset front wheel with axle showing more space.

Offset front wheel with axle showing more space.

Eventually you’ll have enough space to offset the wheel once the axle is placed back into it. You will want to do this for both of the front wheels. The more space you can get the better, so it will allow you to comfortably place a lock washer and nut to attach each wheel onto the spindle.

Once I added enough new threads to both axles I inserted them back into the wheels. I then placed both wheels into the spindles and sat back happy with the results, for the most part. I soon realized that that since the plans call for creating custom wheels, the position of the spindles is ideally suited to those custom wheels. And not so ideal for my wheels.

In our case the wheel doesn’t quite spin freely as the spokes, ever so slightly, want to hit the very edge of the control arms. Not so much that a rough file and some 80 grit sand paper couldn’t solve it. Now we’ve got the front wheels more or less mounted.

Wheel axle extending through the spindle.

Wheel axle extending through the spindle.

Now let’s focus on the back wheels. As is often the case the brakes are often an afterthought with homemade, wooden, go karts. I know back when I was a kid the one we rode around on did in fact have brakes, they just happened to be attached to our feet and said “Chuck Taylor” on the side.

Since for every action there is typically a reaction (i.e., child jumping on couch results in emergency room trip…don’t ask me how I know this) I think brakes are pretty important. If for no other reason that you can make really cool skid marks on the sidewalks.

One of the goals with using the wheels from a bicycle is that I wanted to leverage the coaster brake assembly. I wanted to have a means for the rider to push down on a pedal, or in some other way, cause the coaster brake to engage. At the same time I wanted to be able to use the existing sprocket on the rear wheel to provide movement. At the moment I won’t be using a motor, but if I could somehow setup a chain/pedal drive perhaps I could use the rear sprocket to move the kart, but also allow the driver to pedal backwards and engage the brake. Easy as cake right? Sort of, but I guess it depends on what kind of cake you’re talking about.

If you look at any typical bicycle rear wheel (one with a coaster brake) you have the sprocket mounted on the right side, and on the left you have the lock mechanism for the coaster brake. This is typically mounted to the frame and when the user hits the brakes (pedals backwards) this prevents the brake mechanism from rotating and the brakes engage inside of the rim. Since I’m not mounting my wheels on two sides, like a bicycle, how would I mount this lock piece?

I took a break to sit on the front porch and enjoy an Otter Pop (an orange flavored Otter Pop to be specific) with the boys  and think about this for a bit. If I could put it on the same side as the sprocket, and have that sprocket side closest to the kart frame, that would be great I thought. I asked the boys what they thought and they agreed. I appreciated their feedback, even though I knew very well it was the Otter Pops talking. They then asked if they could have another one.  “No, you can’t have another one.” I said. I think they were expecting somesort of kickback for agreeing with me. At any rate, let’s put my theory to the test.

If I take the rear wheel of the bicycle, and simply place it at the left rear of the kart, I have my sprocket closest to the frame.

Coaster brake arm removed ready to be put on the other side.

Coaster brake arm removed ready to be put on the other side.

Reaching back to my Otter Pop Epiphany I removed the coaster brake arm and then looked to place it on the same side as the sprocket.

Not surprisingly it didn’t fit. There is a nut on this side, as there is on the other, that is squared on two sides. The only thing is that the nut on this side is slightly larger preventing the arm from sliding over it. Meet my little friend the file.

I took the retaining arm and filed about 1/16″ of an inch from the top and bottom of the hole thereby allowing it to slip over this larger nut. I then put the nut back over the axle to hold it in place and voila. I now had my “drive wheel” with a brake system ready to use.

At this point we have our front wheels in place, and we have the solution for the left rear (by far the more difficult of the two), solved for the moment at least. For the right rear wheel we also wanted to have the sprocket closest to the frame. We slid off the coaster brake retainer, as we had on the other wheel, only in this case we set it aside. Since we won’t be using this wheel for power or brakes, we just left it as is.

Rear wheel mounted to pipe flange and wood block.

Rear wheel mounted to pipe flange and wood block.

To mount the rear wheels to the kart it was quickly clear to me that I needed to come up with something that was strong, and flexible as well as something that would account for the narrowing frame.  You see the frame narrows considerably in the front. Simply mounting the rear wheels straight to the frame would result in the kart not rolling very well since the wheels wouldn’t be square. The rear wheels would have some serious toe-in.

In addition to the alignment issue, I needed to have some flexibility to allow for sliding the wheels forward or back to adjust chain tension on the left side. Remember, we want to use the left rear wheel sprocket as a drive wheel.

In searching for a solution here  I discovered that the axle fits perfectly into a 1/2″ galvanized pipe floor flange. I then mounted the rear wheels to one of these flanges. I mounted the flange to a block of wood, and mounted the wood block to the frame. Very complicated I know, but that’s how I roll.

All four wheels now mounted to our frame.

All four wheels now mounted to our frame.

I mounted the other wheel/block combo to the frame and voila. I’m starting to see something that could pass as a vehicle of some sort.

With this phase of our project we found four matching wheels, resolved axle issues on the front, mounted our wheels and discovered the creative inspiration that only a sugar rush from Otter Pops can provide.

Next stop some body work.


Lower control arm ready for it's anchor bolt.

As I noted earlier, all of the parts from this project are readily available at most hardware stores. At this point I have my frame more or less together. Prior to squaring it I had to temporarily mount the upper and lower control arms. Once that was done I then removed them and drilled the holes for the king pins (or spindles). The spindles are used as a mounting point for the wheels, but also will provide roughly 40 degrees of turning radius. Go karts are definitely much more fun if they do more than just go straight.

The spindles each consist of 1/2″ galvanized pipe T fittings and are anchored in place via 3/8″ to 1/2″ pipe connectors. It’s really quite a simple and clever setup.  First, I set a center point 1/2″ in from the end of both the lower and upper control arms and drilled a 7/8″ hole about 1/4″ deep using a hole saw fitted to a hand held drill. In rummaging through the endless drawers of my Dad’s tools I realized he had a number of these which made me wonder, why? Some of them had wood bits still within them from the various projects he had done over the years. Luckily for me he wasn’t one to hesitate to run out and buy a specific tool for a task that he would use only once.

After I drilled the larger, outside hole, I then drilled a smaller hole the same size as the threads of the pipe nut in the photo. The idea here is that the nut would be carefully threaded into these holes. Once threaded down the nut would sit nice and flush in the control arm. To get that nice and flush fit took quite some time since I had to sand, and file carefully to slightly enlarge the hole otherwise the control arm would crack or split altogether. You will want to thread this bolt through so that a few threads are exposed on the opposite side of the control arm. At one point I wasn’t able to easily thread it far enough so rather than push it and risk cracking the control arm I took the hole saw out and drilled down a bit further, allowing the bolt to sit slightly lower in the hole.

At this point the thought did enter my mind as to whether or not this would be strong enough for the boys to ride on, let alone to even drive. I figured that the existence of these plans at least implied it was tested after being built, so I put that thought in the back of my mind and pressed on. In all likelihood the overall structure will only get stronger as more of it gets assembled… right?

Bottom control arm with both spindle holes set.

Bottom control arm with both spindle holes set.

Next I mounted the lower control arm back onto the frame. You can see the holes in the top of the frame rails where I had previously mounted the arms for squaring up the frame. From here you can also see the narrowing of the frame to accommodate the turning of the front wheels. I’m not sure how critical having the frame narrow like this is, since the result is that the back is a few inches wider. The plans call for this so I’ve gone ahead and followed it verbatim. As I quickly realized later, that narrowing is a bit of a pain for a number of reasons but I’ll get to those soon enough.

Before I follow up with the upper control arm I need to now insert the T fittings that get sandwiched in between them. First the large connector nut is carefully screwed into all four holes; two on the lower and the two upper.  Next I insert the T fitting into each nut on the bottom, carefully not forcing it to turn too far, and keeping it slightly loose so that it can turn easily. I’ve also added a bit of white grease to the threads for good measure. The easier these turn back and forth the easier the overall turning will be for the kart, so it’s important to spend the time here to get this right.

In addition to the goal of  free spin here, I found I also needed to account for the vertical space limitation. That is if I had the threads backed off too far the control arms wouldn’t mount back onto the frame without a big gap, but if I threaded them in too tight they wouldn’t turn freely enough. I could always insert a shim or something to account for that extra space, but I really didn’t want to do that.

After an hour or two of sanding, threading, some “Dad is the go kart done yet?“s, more sanding and more threading I was able to get the nuts through and the T fittings in place comfortably.

T Fittings mounted in lower control arms.

T Fittings mounted in lower control arms.

With the T fittings mounted onto the bottom, and enough play to both spin, but tight enough to fit in the space between the two control arms I then mounted the upper control arm back into place. Once the arm is in place and screwed back onto the frame you realize that there really isn’t anywhere for the T fittings to go. Even if they were to completely unscrew (which is virtually impossible since they’d be attached to tie-rods) the control arms have them sandwiched in place so again, a simple and pretty clever assembly overall. My Dad would be proud. 🙂

Once both control arms are in place you can see where the threads on the top of the upper control arm, and bottom of the lower control arm, come through just a bit.

Upper and Lower Control Arms with T Fittings in Place

Upper and Lower Control Arms with T Fittings in Place

The plans call for a 1/2″ electrical conduit lock nut to help to secure these in place.  Although these would do the trick they’re not very attractive. You could also use a galvanized pipe cap, but I realized that a brass garden hose cap fits perfectly and could be polished up quite nice. You can see the brass cap here in this picture with everything all in place nice and tidy like.

So far we have our frame, we have our upper and lower control arms, and spindles all mounted. I’ve even gone so far as to drill the holes into the spindles allowing for me to mount the wheels.

Oh wait, wheels. That’s right this thing needs to roll!!??

I was really anxious when I ordered my plans, even going so far as to pay extra for overnight shipping. The order form indicated as such but they meant for air-mail specifically to account for international delivery. I was quickly informed via email that since they were coming from Texas, and “since as far as we know Texas is still part of the Union we’ll just refund that extra“. That was sure nice. A couple of days later, the plans were in my hand.


Bugatti Pedal Car Plans

I was definitely not disappointed. I read a note somewhere that these plans were somewhat dated. I suppose you could say that, but not too much so. Apparently they had been published in Popular Mechanics at some point in the early 80s, but since the parts referenced are all from a hardware store it’s all still very applicable. In fact the parts are probably now much cheaper and more common.

You get two full pages, back to back, with accurate illustrations and descriptions of the overall building process. One challenge was in some cases the steps described reference an illustration that was on the back side of the same page. I found myself often flipping the plans back and forth, over and over. It would have been nice to be able to read the descriptions and see the corresponding illustration side by side, but really it’s not a big deal.

It appears the whole thing was set on a typewriter so the layout of some of the text is a bit cramped, specifically the shopping materials list. I ended up just buying the materials as I needed them which was better in my case since I was deviating here and there anyway. No sense in buying materials I wasn’t going to use, although for future reference Home Depot has quite a generous return policy. In cases you may even refer to it as an employee there did as  “a rental policy“. 🙂


One rail cut out, now tracing for the other.

I started off with the frame rails. Using 2×6 pine I first drew out the dimension, I cut the one out, and then used it as a template for the other side. After cutting them both I then connected them with the rear cross member using 2″ wood screws. I questioned using simple wood screws, but figured that since the target riders are the boys ( < 75lbs )  it would be fine. Should I build a larger one someday, for say, a man in his 30s (wink wink nod nod), I’d use nuts and bolts where I could or come up with an entirely different more robust frame.

Mounting the front upper and lower cross members was a bit of a back and forth procedure. I first cut them out in their raw shape, and mounted them temporarily onto the rails so that I could get the overall frame square and aligned.

I quickly realized that the task of getting the front cross members mounted permanently would be something for another day, since doing this involved drilling the upper and lower mounting points for the kingpins. After a few hours work I have what is beginning to resemble something, just what I wasn’t quite sure of.


Frame with rear cross member glued and mounted into place.

Even with these first few steps in my mind I’m ultimately picturing the final product. You almost can’t take on a project like this, something that has so many steps that are dependent on one another, unless you can visualize what the end result will be. Without that vision you’re really just walking in the dark hoping that it will turn out to be something worthwhile.

I’m already convinced this will most definitely be something worthwhile. At this point I brought my wife to check out the progress. “Isn’t it looking great!” I said.

Ummm, uhhh yeah.  Looks good.” she enthusiastically replied.

I wanted to say “Non believer! You probably never wanted a go kart when you were little!” but figured it wouldn’t do much good. Better off to just wow her with more progress.

Now the boys, they’d be a good source for moral support, right!?

My oldest keeps saying “Dad, I’m sure I’ll love this go kart even if it doesn’t turn out good.

You guys are killin’ me. Now to find another day when I can sneak in more work.