You thought you had this great idea and that idea was to use the riding lawnmower or the old John Deere tractor sitting in the backyard and make a go kart out of it. But that idea seemed to fade as you started trying to use various components off of the riding long mower and found that they were really not working out very well or it was taking a lot of work to get them to actually be usable on a go kart.
The Big Problem
One of the biggest problems you run into is actually using the wheels that come off of a lawn tractor and adapting them so they will mate with a go kart axel.
There are two problems you’ll run into when you are trying to adapt a tractor wheel onto a go kart, they are:
1. The rear hub that comes with the tractor wheel is splined and does not make with any standard axle stock
2. The rear rim and hub are one unit and the inside diameter of the hub is 3/4 inch
1. Splined Rim/Hub
The first rim/tire we ran into actually is quite serious and will require scrapping the hubs that come with the tractor. A special hub will need to be developed that will mate with the tractor bolt pattern. You will have to develop a plate based off of the old hub and then weld the plate onto a hub that you have developed or stock that fits on the shaft.
Keeping the Wheel On
Particular attention will be needed to make sure that the hub that you have developed will not come off of the shaft. This can be accomplished in a couple of ways. First of all it must be understood that the torque load from the axle to the hub needs to be transferred through a key way.
Transfer Torque Properly
Again all torque loading needs to be transferred through a key way. The reason for this is that the key way has a larger surface cross-sectional area to transfer the load. Anything smaller than a key way will not be able to handle the load and will shear off.
2. 3/4 Inch Diameter Hub (Not the 1 incher you are looking for)
The second rim/hub problem actually is quite simple to solve but requires a little welding. First of all the three-quarter inch diameter hub fits perfectly over three-quarter inch diameter shafting. Typical live one-inch axles, have reduced threaded stock that is designed to hold aluminum hubs onto the shaft. However, the length of the three-quarter inch stock is not long enough to stick out the end of the rim/hub from the tractor. Additionally, there is nothing to grab the rim/hub with.
The solution is to make the key way part of the rim/hub. The rim/hub is piloted on the three-quarter inch axle shaft stub. The one-inch keyed hub is placed onto the one-inch axle shaft. Then the hub is welded to the rim/hub. The torque load is taken by the key way in the welded on hub.
However, the rim/hub still needs one more thing to keep in place otherwise it will slip off the shaft. To keep the rim/hub from falling off of the shaft a 1/4 inch diameter hole can be trailed through the side of the welded on hub into the one-inch shaft. The ¼-20 grade 5 bolt can then be inserted and held in place using a nut.
This will effectively do two things: first the key way will take the torque load, secondly the bolt will keep the axle and the rim/hub together. The bolt will not take any torque load but will keep the wheel from coming off of the axle. This is equivalent to using a snap ring.
The same method can be used for keeping the first hub on the shaft. The preferred method however, especially if you’re developing your own shaft, is to hold the hub on with some sort of nut or bolt that threads onto the end of the shaft.
3. Live Axel Hub
One thing that we’ve not talked about and that is the method of using the three-quarter inch rims/hub as a spinning bearing. In other words, the rim/hub is spinning around the three-quarter inch shaft. This is only applicable if you have a welded on or a fixed shaft onto your go kart.
Typically, a long enough 3/4 inch bolt is not going to be available from the hardware store. So what will need to be purchased instead is some three-quarter inch shafting. The conundrum comes in how to retain the wheel and place?
To retain the wheel in place the shafting should be drilled crosswise and then a bolt can be put in place to retain the wheel. There is one serious issue to be aware of however, and that is the wheel will be spinning and can rub against the bolt when it is spinning. There’s rubbing action acts like a saw or a mail or grinder, and will cause the bolt to be sawed off or ground away completely. The downside to this is that the wheel will fall off a go kart.
So, to keep the bolt from being ground away put a simple washer between the bolt and the wheel hub. The rubbing action will be put against the washer and not against the bolt. Obviously, a generous amount of grease will aid in keeping all systems from wearing out. And honestly again the side benefit being reduced friction.
So To Recap:
First,when using a splined axle hub you will have to develop your own new axle hub that will mate onto a live-axel system.
Secondlyif you have a tractor hub that has a three-quarter inch diameter hole that can be adapted to fit onto a live- axel using a welded on hub. A key way transfers the torque and a bolt keeps the hub from falling off the axle.
Thirdly, if you are using a solid axle you’ll need to make sure that you have ample amount shafting and that the axle is held in place using a cross bolt and washer. Ample grease will be required to make this solid axle system to work properly and last.
Yeah, glad i found you guru. Just bought old school go cart/dunne buggie cant decide to heavy for go cart could go off road something. one inch live axle threaded ends for nuts. 18×9,00 rear tires can i go out over the threads a little with rims. Whatever i decide it will have to be something in between a four wheeler and a dunne buggy. but it was well put together. iam 62 and i just sit and admire the welding. I wsh i knew the brand or style its basic but big for a go cart. It just has sprocket chain motor tires thats all. If i give you some specs any suggestions. wheel base axle to axle 52 inches. motor compart 27 inches across. axle about 36 inches weighs about 130 pds.
There are alot of other things to talk about on this go kart…such as sprocket sizes and engine size. If you are looking for “How is my go kart going to perform?”
Bottom line is that 130 pounds seems a little light for a big go kart….we’ll need some more info.
On the surface, having big tires makes for smoking clutches. The amount of torque required to turn them can be quite large, so a well matched drive system is need to account for that. We talk about that in some of our go kart drive system articles on the blog here…or we have a drive system series that talks about both vertical and horizontal go kart drive systems https://gokartguru.com/go-kart-building-202-how-to-use-a-vertical-engine-as-it-is/
I don’t normally reply to posts but I will on this situation.
my God, i thought you were heading to chip in with some decisive insght at the end there, not go away it
with ‘we depart it to you to decide’.
Did you even read the article? Because there are three problems you run into, and solutions were given to each one. The second one having insight which will make or break the project.
Welding a hub on the wheel is huge and simple. Having a nice big wheel, but no way to mount it to a go kart makes the whole project useless. But welding a hub, or a coupler junction, makes that useless wheel now what you wanted in the first place. There are also things to consider when using that junction too, and we pointed that out. Don’t expect a cross bolt to do all the load bearing, it will shear off. The use of a keyway and a cross bolt together will do the trick.
The cross bolt mearly holds the wheel from falling off the hub, where as the key absorbs the impact from torque and driving.
The other two are pretty important too. The one that leaves you scracthing your head is the splined shaft hub…not real helpful on a go kart…that was the one I said “Walk away from.”
The point of this article is to get you thinking before you find an old rider tractor…not all rider tractors are equal, or useful.
i have a go kart with 1 inch shaft with keyway and a single nut that holds a 6 inch rim currently my buddy just gave me a 20 inch 3/4 inch hub how do i make the tractor wheel work
If you examine the 1 inch shaft you will notice that the end of it is threaded and stepped down to 3/4 inch. The 3/4 inch part (the part with the threads on it) will slide into the tractor wheel and act as a locator or pilot. An additional hub with a key way will need to be purchased (you can find them at tractor supply stores, they are designed typically to weld a sprocket onto, so it looks like a 1 inch pipe with a keyway in it). This hub is then welded to the rim of the tractor wheel.
The keyway will transfer the torque. Then to get the wheel to stay in place, a cross bolt is drilled into the shaft (typically a 1/4 -20 high grade (grade 5 or higher) will work best. This bolt is designed to keep the wheel from sliding off the axel, but not to transfer torque. The key will transfer the torque.
I have a three lug 12 spline wheel hub for my sons go cart thats broke and I cant seem to find one to replace it with anywhere ,i dont know the go kart brand either so its kinda frustrating me,any have any ideas?
The real issue is the splined hub. Typically on a go kart the hub has a key way. Sometimes the quickest solution is to get standard components, such as a 1 inch axle that has a keyway on it. The hubs for these axles are standard enough and you should be able to pick up a replacement for it that will fit the tires that you currently have on the wheels that came with the cart.
I know that is probably the answer you wanted to hear, but a 12 spline hub sounds like something that came off of a riding lawnmower. You may want to look on some riding lawnmower sites that supply parts. The best alternative is to take pictures and show them to people, like myself and I can help further. Be sure to take pictures on the axle, the hub and the tires.