This weekend I spent three hours (and several hundred dollars, sigh) on a bunch of mechanical parts for the project, and a little in the way of tools.
I ended up buying the tires that were on sale, they are Carlisle trailer tires, 16.5 inches diameter. Unfortunately they only had 3 in store, so I got a rain check and will have to go back to get the fourth.
I chose #50 chain and a 1" rear axle. Here are the rear sprocket and the motor sprocket, chosen for a gear ratio of about 2.5. I ended up with 48 and 18 teeth, for an actual ratio of 2.66.
The rear wheels are on a live axle, so I have to solidly attach the wheel to the axle. I decided to use a small sprocket, and bolt the sprocket to the tire.
The is just small enough to fit inside the rim, on a 4 x 4" bolt pattern. First I tack-welded the sprocket to the hub, and made sure it was properly seated and square. I drilled 1/4" holes on a 4" circle - the milling machine and rotary table at work came in very handy here. You could do it by hand but it would be *even more* time consuming.
All the sprockets I used are designed to be welded onto the hubs which are keyed to attach to the axle.
So here is the first real welding I have done in a few years, for the rim attachments.
It is fairly ugly, and was hard to take a picture of. A wire brushing would have helped, but I did bang off the slag with my welding hammer. The second hub went much better than the first, but still needs a some more improvement.
Still the first hub. It really is a solid weld, both components are melted and there is decent penetration. I know this is one of the more critical welds in the project for my safety, and I am comfortable with them.
I then expanded the holes with 3/8 and 7/16 drills. The bolts I am using were designed for tire applications, to be hammered into the hub. Of course the dimensions are not handy; the threaded section is 1/2" but the flat area is 0.53" and the ridged area which provides the holding effort is about 0.55".
I had to use the mill here again to get the dimensions right; I don't know exactly how big the hole was but just over 0.53".
See the ridges don't quite fit? This is perfect. Now you have to beat the shit out of the bold head to drive it into this sprocket, which I swear is hardened steel. It was very difficult - if I made the holes larger it would have been easier, but there would have been less grip strength in rotation.
Hey, it fits!
Here's the bolt side.
You can't tell but the ridged area is too wide, so the nuts don't completely seat. I need to add spacers for a better fit. I should have used thicker sprockets instead.
Both sprockets together
Hammered-in detail. See the sprocket was deformed by my intense hammering.
Here's the posi-lube stub axle which I will be using for the front axles.
Stub axle detail.Very overkill, but it's a bearing and hub I don't have to assembly. Weighs a ton.
Brass bushings and 5/8" bolt as kingpin. Will use half of each bushing, take the other half for the other side.
Motor sprocket on the motor.
1/8" aircraft cable, and accessories for brake and gas.
1" pillow blocks with scrap 1" bar lying around the shop. I chose 1" axle because the 1 1/4" pillow blocks at Princess were not assembled so I would have had to use a torch I don't have to assemble them.. not fun.
The brake rotor -another sprocket, surprise! with the axle gear.
Both tires bolted to hubs and on the scrap 1" bar again.
Motor and rear axle mockup, again with scrap piece.
Next I have to buy a 1" keyed axle, some keystock, locking collars, and a bunch of metal from Metal Supermarket.
Jackshaft 325mm With 5mm Keyway Solid Steel For Go Kart
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Location : China (Mainland)
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Maximum Speed : 60h/km
Displacement : 250cc
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