Make a go kart with a lawn mower

You may have a ride-on mower in the backyard that became too much work as the deck rotted and the mower stopped working. All the ride-on mower is good at now is towing wagons, and it’s not very good at it. One thing that depends on the lawnmower is the engine, tires, and a few other essentials for a fantastic go kart.

Unfortunately, the ride-on mower requires some education to drive, a clutch here and an adjustment there is required to get the unit working. Therefore, using the mower as a makeshift go-kart is neither realistic nor safe.

You had some other intentions for this rusty helmet that you haven’t discovered yet. You still haven’t figured out how it’s possible to transform the lawn mower parts into a go kart that is sure to put a smile on everyone’s face.

The transformation requires the following:

1. go kart map
2. vertical motor drive
3. Pipe for framework
4. Wood, fabric and foam for the seat.
5. Rear axle and drive sprocket
6. rear axle bearings
7. Clutch
8. string
9. braking system

Tools needed:

• welder
• Hacksaw of saws – all with metal cutting blades
• Standard wrench set (includes allen keys, hammer, sockets, locking pliers and screwdrivers)
• Drill and gold drill

The rest of the mower elements can be used for the kart. The front tires, the rear tires, the steering gear, the steering wheel, the pedals, and obviously the engine.

Lawn Tractor Disassembly

To start up the ride-on mower it must be disassembled to find out which parts will work best.

What you will find is that the rear wheels will require some modification, because the wheel hubs are usually built into the rear wheel and require a keyed axle for them to turn. No problem, the wheels can be adapted to fit a standard kart axle by simply welding a 1 inch coupler to the wheel hub. The coupler is then held in place with a cross bolt, preventing the wheel from slipping off the axle shaft.

The front wheels can be removed from the mower, or the entire front axle system can be cut in two and then widened to the desired width of the go kart. Usually the width of the frame is 20 inches and the wheels are spaced about 40 inches apart.

A good go kart plan will have a simple steering system, so in the end it might be easier to scrap the steering system and use the parts the plan shows. Typically, the plan will allow you to fabricate the steering system from tubes and plates. A good knowledge of a drill and welder is helpful here. Save the steering shaft and steering wheel to attach to the kart later.

Go Kart framework and plan

The frame should be built using the go kart plan as a guide. A typical flat style go kart will require a flat garage floor for proper frame alignment. The go kart plans I prefer require side profile systems to be built first and then attached with cross pieces. The side pieces are similar to bridge beams and provide a safety measure that acts as a restraint to prevent occupants from spilling out. Additionally, the truss system provides almost three times more strength than a flat style go kart. And finally, the truss system gives the kart an aesthetic look or cool look.

The frame is constructed of 1x1x0.08 square tubing that is cut to proper dimensions and then placed in a pegboard style fixture to align prior to welding. The tubes are held in place with 2×4’s that are screwed into the board. The 2×4’s are positioned so the tubes cannot move and are held in place as if building a picture frame. Once the pieces fit properly into place, the tubes can be tacked on and then the entire fixture side unit can be removed.

Once the side units have been built, the center spacer tubes can be placed between the side units and then fixed in place as well. Once the entire frame has been tacked on, the entire frame can be welded solid.

Plates and Engine Mounts

The next step is to fit the plates that hold the pedals, the steering gear, the seat mounts, and the motor plate. If a vertical engine is used, the lawn tractor engine mount can be cut with a hacksaw. (This will take about 20 patient minutes of cutting. Be sure to wear earplugs and have extra blades on hand. Lubricating the blade helps keep it from dull too quickly.)

The vertical motor can then be fitted to the frame around a vertical motor drive system. Some users will try to use a transmission from a lawn mower, however this can actually be quite fiddly, heavy and not wide enough for the go kart you are doing. Others buy a second hand right angle transmission. The best solution is to use the vertical motor and mount it to the frame without adding a lot of weight, then fit the motor to the vertical motor drive.

rear axle

The next phase is to mount the rear axle according to the plan of the kart. The axle is held in place by support plates that protrude vertically from the frame rails. The bearing is mounted in the cutout of the bearing plate. The positioning of this plate dictates where the wheels will sit both lengthwise and vertically on the go kart frame.

Rear axle location is critical to proper weight distribution, which dramatically affects steering. This is known as 50/50 weight distribution. A good go kart plan will take into account weight distribution and the location of the front and rear axles. Once the rear axle is in place, slide the rear sprocket and rear brake disc into place then mount the rear wheels to the rear axle and check the ground clearance.

The ground clearance is usually the thickness of a 2×4 for good handling.

The output shaft for vertical engine drive will usually have a clutch mounted on it. The chain can then be mounted to the clutch and rear drive sprocket. This is where I like to have a chain tensioner because it doesn’t require the rear axle to move backwards or the motor system to move forward. A simple roller skate mounted on a hinge system (spring loaded of course) will provide the proper chain tension. Be sure to place the tensioner on the slack side of the chain (ie the lower side of the clutch system).

Direction system

The next phase is to mount the front steering system. The front steering system is usually a 1x1x.125 wall cross tube with steering knuckles mounted at each end. I like to mount the head tube with plates so I can remove it. It also allows the steering system to move forward or backward. The steering axle is mounted to the cross tube via a hub plate that is welded to the cross tube. The steering axle is supported by a vertical tube that comes out of the frame itself. This prevents the steering wheel from moving side to side, up and down, and in and out.

Then the steering wheel can be mounted on the steering shaft. The steering linkage is attached to the steering axle plate and then the linkage goes to each front wheel knuckle. Make sure the steering system is tight and not loose when complete.

The seat

The next phase is seating. Usually a seat is built of wood. A cushion is then inserted into the wooden frame. The entire system is then covered with a vinyl material or heavy cloth. The cover is held in place with an industrial-type stapler on the back of each seat. The seats consist of a seat and a backrest that is tilted upwards by about 15 degrees. The plates that were mounted to the frame have holes where wood screws can be screwed into the seat backs to hold the seats in place.

Mounting the pedals

The next phase is to put the pedals in place. The key to the pedals is that they spring back into position with the force of the spring. For the throttle I like to have a spring back when the motor pulls hard so when the throttle is released it slams shut. Same for the brake, I like to have a large return spring pulling back on the linkage.

Brake mounting

Now you can put the brakes on the frame of the go kart. The major problem with kart brakes is that they float. If they don’t, they will tie up. The best you can do is let the disc float and lock the brake mechanism to the frame.

Bottom plate mounting

The final phase is to place the fitted sheet on the frame of the go kart. This is essential to prevent foot injuries. Provides a bottom guard that is essential to kart design. The sheet may be made of sheet metal used in ductwork. The easiest way to mount the sheet is to use a self-tapping, self-tapping screw and turn it on with a drill. Space them about 3 inches apart.

final checks

Make sure all parts are tight and not wobbly. Also make sure the drive system is actually working. And obviously double check that the brakes actually work. It’s a good idea to have a kill switch, which is basically a wire that goes to the lead wire (typically black). When the switch is activated, it cuts the cable to the frame and stops the motor.

The amount of time required to make such a kart is about 7 weekends, if not more. Be prepared for the long haul on this project, but it’s well worth it when completed.