General questions

[djh07]

I have decided I am going to build an off-road kart. Not anything crazy, but a modest kart as my first one.

I have decided I want a live axle. I have seen a few different sites, but I am very confused. Some have axles that are round but a square sticking out, others are round with a square sticking in. I'd assume you need the "in" because the "out" wouldn't roll.

In your opinion, what are better: Pillow block bearings, or a live axle bearing kit like this http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_21915_21915

Do you need collars with the pillow block bearings to keep your axle in place laterally?

How long of a chain would you recommend buying? I don't know exactly what engine I'm going to have available, but what are some guidelines in choosing a chain length?

Is there a guideline for sprocket teeth vs clutch teeth vs engine horsepower? I haven't looked too much into this yet.

I'm sorry if these are repeat questions, I did some searching but nothing too extensive on everything yet.

 

[mikeandike]

About the squares, they're called keyways and normally they're sticking inwards and on parts that need to spin with the axel (wheels, sproket, brakes) they have a slot in them too and you put a piece of square bar in between them called a key (or keystock) to make them spin together. Normally there is a setscrew of some sort to keep them from sliding around on the axel.

Im not sure about the bearings. I used pillow blocks simply because my frame is aluminum and the weld-on ones are all made of steel.

Yes you need locking collars and im pretty sure the pillow block bearings come with the collars.

I bought my chain from princess auto for around 12$ for 10 feet. You have to resize your chain to fit. (theres a special link that comes apart)

A few common ratios are:

10 tooth clutch, 60 tooth axel (i used this one)
12 tooth clutch, 60 tooth axel
12 tooth clutch, 72 tooth axel

hope this helps

 

[RobertD]

I buy chain in the 10 ft sections from northern. I haven't found a better deal yet.

I've used this live axle and this bearing kit. For that, there are hex bolts that screw into the axle to hold it laterally. I ended up drilling a small indention from the axle so the bolts could seat better and hold it in place.

You must buy wheels that will fit this type of axle -- one side will have the "locking to the axle" part. Basically one side is the 3/4" size, the other side is the 1" to fit over the axle. I used these on my bar stool racer.

Sprocket sizes are usually 10-12 and 60 in the back, 72 for a mini bike.

 

[djh07]

In looking at different options and usage, the kart I'm going to build will be used mostly on grass and light dirt but relatively hard ground. Nothing off-road, I won't even have a suspension for this one. I'm thinking a fixed axle is going to be my source of power for now.

For that, I am under the understanding that you'd need double-flanged hub to connect the sprocket to the wheel, and possibly a brake in there somewhere. I know that single wheel braking isnt the best, I'm thinking about 2 wheel rear brakes, but who knows right now. What are your opinions for drive systems on grass (think former horse field/pasture, somewhat smooth)

 

[RobertD]

live axle!

 

[the thnikkaman]

A live axle will give you the best traction on grass. Since you plan on driving the kart on grass, scrubbing (when the two wheels cannot move at different speeds because they are locked together) should not be a problem. A live axle will also allow you to mount one brake for both back wheels.

 

[djh07]

Well, I figure I'll build a fixed axle for now, and I can always buy a live axle assembly and put it on, just a few cuts and the old one's off. I'm running on limited funds, I've got my costs down to 87$ from BMI for a clutch, sprocket+drive hub, chain, and brake. I should be able to come up with the rest from local junkyards or fabricate what I need. I'm confident that I'll be able to make the entire front end, and possibly even a steering wheel. My next kart on a bigger budget, I might be able to buy the right stuff, but this should be a good project for me right now.

My plans are below, thats the main idea of it. When I build it, I'll probably fabricate some sort of bumpers and protection for the engine. Its based off of the kart design on the DIY site for one person. Its a little longer, a little wider, but should be pretty good. I'll probably add some more tubing, maybe a cage, I'm not sure right now. I don't like the length at the end, kinda hangs out.




Let me know what you guys think. I'm gonna start looking around for an inexpensive motor, and probably call the local scrapyard/recycling place and see if they can help me out with about 40 feet of angle iron or square tubing.

 

[RobertD]

looks cool!

I found this week that the dump is actually a good place for engines -- a lot of people throw away garden tillers, and our local dump puts aside things for resale. There were a lot of tillers.

I dont know if your local dump has a re-sale area, but you should call.