DIY Go Kart Forum

DIY Go Kart Forum (
-   Mini Bikes, Trikes, and Choppers (
-   -   Building a mini-chopper; questions (

cojaro 08-01-2006 10:00 PM

A few things have been bothering me about the build of the bike, and I still can't figure them out.

1) How is the hub connected to the axle?

2) what is the function of a keyway? How is it used? I'm clueless why the axles have these.

3) Where are the bearings on your bike? and where do they go on a normal mini-chopper.

Other than those three questions, I've got everything else down. But, you know, bearings and hub connections are kinda vital. :P

imported_robertdjung 08-01-2006 11:34 PM

Great questions, and that's got me thinking about how I need to update the information to be more clear! Thanks!

OK, hubs connect (or not) in two ways.

Live Axle: The hub is fixed to, and turns with the axle. The axle itself rides on "pillow block" bearings. The axle turns.

Fixed Axle: The hub has it's own bearings, and those bearings turn on the axle. The axle doesn't turn.

A keyway is needed with a live axle. This is to connect the hub to the axle. A "key" fits in the keyway and that makes a solid connection between axle and hub. Then the axle turns, and the hub is fixed to the axle, turning with it.

#3 -- matters. On my chopper I used a fixed axle, so the bearings were in the hubs, and the axle itself doesn't turn. On my next chopper I'm probably going to use a live axle because it's bigger, and I'll use pillow block bearings. Those bearings have mounting hardware to mount the bearings to the frame, and then you slide the axle through the bearings.

So, it just matters what you want. I'd use a fixed axle, personally. I think it's just easier. To see that, just check our plans.

Keep us updated and post some photos whenever you have time!

cojaro 08-02-2006 01:15 AM

I'm going the fixed axle route, with a 5" rim that's 4" wide, and a drum brake/sprocket combo.

Where will the bearings go? Onto either side of the tire only? I just wanna make sure that I'll be doing it right.

Also, I'm having trouble firguring out what goes where, because doesnt provide very big pictures.
How does the braking platform attach to the sprocket/brake drum?

imported_robertdjung 08-02-2006 03:03 AM

check out my pics on my chopper plans -- they'll show how i mounted the wheels. I fabricated some spacers -- I have no idea how else people do this, so anyone, feel free to chime in!

bearings go in the hub. The tire is mounted on a wheel, and the wheel is mounted to the hub. Some wheels have integrated hubs, but those are usually for the front. the hub is basically just the thing the bearings go in that you mount to the wheel. Check the pics. And feel free to post pics of anything!

imported_robertdjung 08-02-2006 03:10 AM

I just looked at those parts -- and half are for fixed, half are for live axles! Watch out!

the 'revited hubs' are for live axles. the sizes drum brakes i think are also for live. as a kid i bought one of these and just welded it solid to my fixed axle --- so you can do it, just be aware..

this is one of the reasons I recommend northern. check the "parts" section of this site and it'll show more ideas, and has links to the different parts sections on the site (as frank pointed out it's hard to navigate). Either way they sell stuff that's already paired together that i found useful. shows a combo they sell. Then you mount a band brake to it.

Also check the chopper plans where I show you how to mount a disc brake direct to the sprocket. Careful--this probably is not a good idea, and use your own judgment.

cojaro 08-02-2006 12:55 PM

OK, so I've come to a parts list that I hope will work for my setup

1) 5/8" bore mini-bike Axle (length to be determined)
2) Brake drum/Sprocket combo (60 tooth) with 5/8" bore, 3.75" bolt pattern ( made for 4.5" brake below)
3) 4.5" drum brake w/ mounting plate and 5/8" bore
4) 5" rim with 3.75" bolt circle and 5/8" ID bearing type, for 1-3/8" OD bearings
5) brake mount (to mount drum/sprocket to rim)
6) Bearings 5/8" ID and 1-3/8" OD

I think that'll be my rear axle setup. All from gokartgalaxy and everything should fit together. Northern seemed a little pricey compared to the other three stores I looked at. Gokartgalaxy seems to have some good buys.

Think that setup will fir together and work?

imported_robertdjung 08-02-2006 01:44 PM

looks good to me! i like those integrated sprocket/drums as well.

cojaro 08-03-2006 12:33 AM

I was looking at the rims and...

I don't know how to inflate that sort of tire. Will the 5" rim come with a vavle hole, or do I have to buy something else to adapt it?

And what are the inner tubes used for?


imported_robertdjung 08-03-2006 12:40 AM

the tube is how you inflate it. It's like a bicycle. the tube is inside the tire. That's what the stem connects to.

cojaro 08-03-2006 12:46 AM

So I have to buy both the tube and the tire?

Sorry, still trying to understand how everything works, and these pages seem to be the only ones with the most info about mini-bikes/choppers.

imported_robertdjung 08-03-2006 12:24 PM

No problem at all. I forget myself how confusing it is when you don't have all the parts laying in front of you!

Yes, you'll need a tire and a tube, unless you get some kind of setup that is tubeless, like ATV tires. But all the 4, 5, 6" "go kart wheels" with the split rims are tubed.

cojaro 08-03-2006 04:49 PM

OK! Looks like ai have a complete parts list, except for the engine and clutch. I'm going to check my local lawnmower service place, see if they have any cheap. and THEN I'll get the clutch, since I need to know the shaft size on the engine before I get the clutch.

Know of a place that has a 2 speed non-torqconverter clutch? I thought I saw one while looking at parts a few days ago.

Mmm, it'll look good hopefully. I'm gonna use a 5" rim in the back, and a spoke 10" rim in the front. Delicious.

imported_robertdjung 08-03-2006 05:30 PM

I haven't even heard of a two speed clutch. if you run across it again post a link!

cojaro 08-07-2006 12:18 AM

It's actually a jackshaft, but not for a torque converter.

And also. Did you use bearings in the tube where the fork is connected to the body?

imported_robertdjung 08-09-2006 10:11 PM

i didn't. i just used a really close fit. it's tubing with a bolt run through it so it's a really good fit. I posted something about this on the forum last week i think... lemme see if i can find it.

imported_robertdjung 08-09-2006 10:17 PM

seney2 10-24-2006 06:24 AM


Originally Posted by cojaro
It's actually a jackshaft, but not for a torque converter.

And also. Did you use bearings in the tube where the fork is connected to the body?

The two speed jack shaft in that link works great! My LHS Knight Bike has that setup with a briggs 6.5 hp and it's been clocked at 45 mph with a 200lb rider.....

jrjulien1 10-24-2006 01:06 PM

thanks for the info i was planning to use one of those 2 speed jackshafts on my go kart project and was wondering how well they work

imported_robertdjung 10-24-2006 01:24 PM

that's a really neat clutch system... I'd never seen that.

seney2 10-25-2006 12:03 PM

Shifts great too.... Nice off the line... then just when you think you're at top speed it takes off again.... you don't even feel it kick in.... all the chains are noisy, but I like that!

All times are GMT -6. The time now is 08:06 PM.

Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.