Off Road Go Kart You Can Drive With Your Kids

Why to make a gokart ? Mainly for fun and for kids. Such cars are not expensive and really fun to ride. Believe me :)
But what if You have two kids and one of them is to small to drive a little car ? Just make two seater gokart and You will be able to control the ride with smaller one.

Gokart which I'm showing to You is capable to drive on off road areas, on gravels and even mud. It doesn't have much power, but enough for country roads for two adult persons.

So let's start.

Step 1: Parts and Tools Needed to Make a Go Kart

Parts
First of all buy the main parts like rear axle, wheels, maglov etc. Why parts first before the design ? As I said, the car have to be cheap so You will need to buy parts on several different auctions, scrap yards and different shops. They should be compatible with each other, but not from one specific vehicle.

My parts are from:

wheels - from ATV/Buggy - 7" typical and easy to find
tires - as above - 19" easy to buy
shock absorbers - from cheap chinese quads
rear axle - spare part from some Chinese little buggy (105 cm wide, 30mm in diameter)
maglov - from fiat tico - scrap yard
kardan and wheel - from hiunday - scrap yard
hydraulic breaks - from cross motorcycles - easy to find on auctions in internet
spindles - from quad

Apart from above You will need the metal profiles/tubing. I recommend to use 30x30mm or 30x50mm. They should be strong enough.

Tools

You will definitely need some tools to make a car. Sorry, but without the: welder, angle grinder and drill You can't do anything. Those are only 3 needed tools but You have to make all of them to complete the project.

Apart of this 3 main tools very useful would be: table grinder or metal cutter, table drill, sandpaper grinder, lot of clamps and magnetic metal holder.

Step 2: Design

When all main parts are bought, it's time to make the design. You can make it on the paper, I used some free open source software (freecad).

I'm not the proffesional designer, so I just make the project to see the proportions, lenght and angles of elements. I'm adding the project here, maybe someone will use it.
Project will help You to see the car before You will do it, so You would avoid making ugly, not proportional little monster like You can find on internet when You google 'diy gokarts' ;-)

Step 3: Frame & Welding

First of all, I would like to show, that welding the frame it's not so complicated and apart the welder You don't need to much to complete the task.

I've made a frame from metal profiles: 20x30mm and 30x50mm (3-4mm thick). The wider one I used for the most important parts like frame or engine holder. The thinner one were used in less important elements like front 'hud', trunk, seats, etc. Of course You can make the whole frame from wide strong metal, but take in mind, that the gokart should be light (because of small and cheap engine).

I used welding electrodes from 2,5mm for details, 3,2mm for the frame and 4mm for the thick plates which were used for the hinges to rear and front suspension (it should be from thick metal in my opinion). What is important, during welding You need to be very careful, the frame should be welded maybe not very pretty, but definitely very well and strong.

If You welds are not so pretty, just sand them and You will get flat, nice connections.

I'm not a welder, so I didn't have many welder's tools like magnetic holders, table etc. It would be helpful but those are not necessary. You can see on the pic/vid that I will manage to make frame alone without those welder's things using just wood clamps and some 'strange' constructions to hold elements in right positions.

Making the frame is the most time consuming part off all. It seems to be easy, but cutting and welding in right angles can take huge amount of time. Use the leveling tool and protractor for measurements a lot and You will get nice, straight frame.

Step 4: Rear Suspension.

Rear suspension is simpler than front one, so let's start from it. The engine will drive the real axle with chain, so the chain have to be the same length all the time (or it will fall off). This is the main reason that You have to make suspension which will absorb shocks to both: engine and rear axle. You can see on the pictures that it's not complicated thing to make. Just frame for engine&axle connected with shock abosrbers and movable joints made from thick metal plates with the rest of the frame.

Step 5: Front Suspension

More complicated is front suspension. If You plan to drive through woods, gravel etc (and I believe that You are planning that since gokarts aren't street legal ;-) ) the best choice is independent suspension for each of front wheels.

The suspension is made from A shaped pieces of metal. I've welded the screws to the end of them and screw there the attachment for the spindles. The A shaped swingarms are connected to the frame of the car through the metal pipes filled with rubber bushings from chinese quads (to absorb more shock). Last step is to add the shock abosrber to each of the wheel. I recommend the adjustable absorbers so it will let You easily adjust the suspension to the actual load of the car (one child weights significant less than e.g. child and adult).

Step 6: Steering and Steering Wheel

I've seen a lot of patents for gokart steering but I definitely recommend to use the real car maglov, spindles and kardan. Those are important things, so it's better to don't mess with them since the scrap yards parts are reaaaly cheap. It is the best working sollution in my opinion.
I've used maglov from fiat, kardan from Hyundai, steering wheel from some another car and spindles from quad. Of course all this things were not 100% compatible, so In my case, the maglov from has to wide rods, so I just unscrew them, cut some in the middle, and weld once again. Now it fits perfectly.

Step 7: Engine, Gearbox, Torque and Speed

I used honda gx clone with the 212 cc. This are vey reliable and cheap engines. In USA You the most popular vendor is Predator, in Europe it could be Lifan. They are however even cheaper engines than those two brands.
However some cheaper engines have some drawbacks e.g. they could have thinner sides or plastic elements inside like crankshaft. However sometimes it is cheaper to buy such engine, drive untli it is broken and then replace the crankshaft to metal one.

Anyway. For the gokart good engines are gx200 or gx212. GX160 in my opinion would not have enough power and gx 270 and gx320 would have too much power for a kid's car.

I mount the variator (semi automatic gearbox) on my engine (available on internet as torque converter), use a 52 teeth sprocket and, with the 19" wheels, it gives me about 30kmh (20mph). It is enough for kids driving (especially in forests, gravel etc).

If You want more speed, You can e.g. lower the sprocket teeth number e.g. to 48 or give bigger wheels. Take in mind that both operations will however negative (but it still will be ok to drive) impact to your torque feelings. Less number of teeth will increase the speed but it will take longer to achieve the top speed.

Gx Engines are limited to 3600 RPM. It is enough for me, my gokart runs pretty well with that. However You can easily change the limpit up to 5000 RPM. This will give You more boost (HP) during acceleration, but it will definitely reduce engine life. I would not worry of that too much. Internet is full of guys making it and they are saying that it is a good idea. I didn't do that however yet, so I'm not recommending it by my name ;-)

One last word about the engine. Power is transmitted to the rear axle through the chain (motorcycle chain 420) and it is powering both rear wheels. This is good idea for not to wide vehicles which are driving mainly on gravels, sands NOT ON TARMAC (You will ruin Your tires faster there).

Engine pros: + price + reasonable power + plug'n'play - everything installed on engine + good, proven, reliable + lot of parts and tutorials on internet + small

Engine cons: - small RPM - designed for pumps/generators etc, so their are generating many vibrations - not very good silencers (loud and reducing the engine power)

Step 8: Seats

You can use seats from shops, but their are expensive. So It's better to build them. I've made them from wood and cover with spoge and artificial skin fabric. Easy work.

Seats are screwed to the metal rails through screws and holes in the frame. I've made several holes so the seats now are adjustable. You can move them front and back a little.

Important thing. The car is for kids, so made a safety belts. I've used the strong belt from rucksack for that purpose.

Step 9: Finishing and Painting

Last steps are easy but most important, because the look of whole car depends on them ;-)

After mounting all parts, it's time to grind and sand the frame and ugly joints after welding. If some welds are not good it is a last time to fix them also.

Painting can be made using brush but instead of that I recommend the spray lacquers. They will give better, more smooth surface.
Before painting I recommend to sand the rust from the metal. Then the first layer of primer and then 2-3 layers of spray paint. That should be enough.