You may have a riding lawnmower sitting in the back yard that became too much work, as the deck rotted out, the mower stopped working. All the riding lawnmower is good for now is towing wagons, and it is not very good at that. One thing that is dependable on the riding lawnmower is the engine, the tires and some other essential goodies for a fantastic go kart.
Unfortunately, the riding lawnmower requires some education to drive, a clutch push in here and an adjustment there are required to get the unit riding. So using the riding lawn mower as a make shift go kart is not realistic or safe.
You had some other intentions for this rusting hulk that you have not yet discovered. You have not discovered how it is possible to transform the parts of the riding lawnmower into a go kart that is sure to put a smile on everyone’s face.
The transformation requires the following:
- Go Kart Plan
- Vertical Engine Drive
- Tubing for the frame work
- Wood, fabric, and foam for the seat
- Rear Axle and drive sprocket
- Bearings for the rear axel
- Brake system
- Hack Saw of saws-all with metal cutting blades
- Standard wrench kit (Includes allens, hammer, sockets, locking pliers and screw drivers)
- Drill and or drill press
The rest of the items from the riding lawnmower can be used for the go kart. The front tires, the rear tires, the steering mechanism, steering wheel, the foot pedals and obviously the engine.
Disassembly Of The Riding Mower
To start the riding lawnmower should be disassembled to find out which parts are going to work best.
What you will discover is that the rear wheels will require some modification, because the hubs to the wheels are typically built into the rear wheel and require a keyed shaft to cause them to rotate. Not a problem, the wheels can be adapted to fit onto a standard go kart axel quite simply by welding a 1 inch coupler to the wheel hub. The coupler is then kept in place with a cross bolt, this prevents the wheel from sliding off of the axel shaft.
The front wheels can either be taken off of the riding lawn mower, or the whole front axle system can be cut in two and then widened to the desired width of the go kart. Typically the width of the frame is 20 inches, and the wheels are about 40 inches apart.
A good go kart plan will have a simple steering system, so it might be easier in the end to scrap out the steering system and use the parts that the plan shows. Typically the plan will allow you to fabricate the steering system from tubes and plate. A good knowledge of a drill press and welder is handy here. Keep the steering shaft and the steering wheel for placement in the go kart later.
Go Kart Frame And Plan
The frame should be constructed 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 that I prefer require the side profile systems to be constructed first then mated together with cross pieces. The side pieces are similar to trusses on a bridge and give a measure of safety acting as constraint to prevent occupants from spilling out. Additionally the truss system provides almost three times as much strength as a flat style go kart. And finally the truss system does give the go kart an aesthetic look, or a cool look to it.
The frame is constructed of 1x1x.08 square tubes that are cut to the proper dimensions and then placed on a board style fixture for alignment prior to welding. The tubes are held in place with 2×4’s that are screwed down to the board. The 2×4’s are placed such that the tubes cannot be moved and are held in place much like a picture frame would be constructed. Once the pieces are fitting properly in place, the tubes can be tacked in place and then the whole side unit can be removed from the fixture.
Once the side units have been constructed, the center spacer tubes can be fitted in between the side units and then they too can be tacked in place. Once the whole frame has been tacked up then the whole frame can be welded solid.
Plates and Engine Mounts
The next step is to fit the plates that hold the pedals, the steering mechanism, the seat mounts, and the engine plate. If a vertical engine is being used, the motor mount for the engine on the riding lawnmower can be cut out using a saws-all. (This will take about 20 patient minutes of cutting. Be sure to wear ear plugs and have extra blades on hand. Lubing up the blade helps keep the blade from dulling too quick.)
The vertical engine can then be fit into the frame work around a vertical engine drive system. Some users will try to use a transmission off of a riding lawnmower, however this actually can be quite complicated, heavy and not wide enough for the go kart you are making. Others purchase a second-hand right-angle transmission. The best solution is to use the vertical engine and mount it into the frame work without adding a large amount of weight, then adapt the engine to the vertical engine drive.
The next phase is to mount the rear axle per the go kart plan. The axle is held in place with bearing plates that stick vertically up off of the frame rails. The bearing mounts in the cut out of the bearing plate. Positioning of this plate dictates where the wheels will be located both length wise and vertically in the go kart frame.
Placement of the rear axle is critical for proper weight distribution which affects steering dramatically. This is known as 50/50 weight distribution. A good go kart plan will take the weight distribution and placement of the rear and front axels into account. Once the rear axle has been placed, slide the rear sprocket, and the rear brake disc into place and then mount the rear tires to the rear axle and check ground clearance.
Ground clearance is typically about the thickness of a 2×4 for good handling.
The output shaft for the vertical engine drive typically will have a clutch mounted to it. The chain then can be mounted to the clutch and rear drive sprocket. This is where I like to have a chain tensioner because it does not require that the rear axle be shifted back or the engine system moved forward. A simple roller skate mounted to hinge system (spring loaded of course) will provide the adequate tension of the chain. Make sure you put the tensioner on the slack side of the chain (i.e. the bottom side of the clutch system.)
The next phase is to mount the front steering system. The front steering system typically is a 1x1x.125 wall cross tube with steering knuckles mounted on either end. I like to mount the steering tube with plates so it can be removed. It also allows the steering system to be moved forward or backward. The steering shaft is mounted to the cross tube by a bushing plate that is welded to the cross tube. The steering shaft is supported by an upright tube that comes from the frame itself. This keeps the steering wheel from moving sides to side, up and down and inward and outward.
The steering wheel then can be mounted to the steering shaft. The steering linkage is attached to the steering shaft-plate and then the linkage is routed to each front wheel knuckle. Make sure the steering system is tight and not loose when complete.
The next phase is the seat. Typically a wood seat is constructed. Then a cushion is inserted into the wood frame work. Then the whole system is covered with either a vinyl material or a heavy fabric. The covering is held in place with an industrial type stapler gun on the back side of each seat. The seats consist of a seat and a back that is angled up at about 15 degrees. The plates that were mounted to the frame work have holes in them where wood screws can then be screwed into the seat backs to hold the seats in place.
Mounting The Pedals
The next phase is putting the pedals in place. The key to pedals is that they are pulled back into position with spring force. For the throttle I like to have a spring back by the engine pulling hard, so that 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.
Mounting the Brakes
The brakes can now be put into the go kart frame. The important issue with go kart brakes is that they float. If they do not, they will bind. The best thing to do is let the disc float and lock down the brake mechanism to the frame work.
Mounting The Bottom Plate
The final phase is putting the bottom sheet on to the go kart frame. This is essential to prevent foot injury. It provides a bottom shield which is essential to go kart design. The sheet can be made from sheet metal used on duct work. The easiest way to mount the sheet is to use a self-drilling and tapping screw and power it in with a drill. Space them out about 3 inches apart.
Make sure all the pieces are tight and not wobbling. Also make sure the drive system is actually working. And obviously double check that the brakes are actually working. It is a good idea to have a stop switch, which basically a wire that goes to the point wire (typically black). When the switch is activated it shorts the wire to the frame stopping the engine.
The amount of time required to make such a go kart is about 7 weekends if not longer. Be prepared for the long haul on this project, but it is well worth it when complete.