Hub Sprocket

[williag]

New to this, but fairly mechanically inclined. I just picked up a Kart with no engine, sprockets, or brakes. Having a hard time finding a drive sprocket that will fit the 3.75" bolt spacing on the hub and accommodate a brake drum. Can someone point me in the right direction. Not a live axle.

 

[anderkart]

I wouldn't be surprised If your kart was made in china, and If so; your hubs bolt patern would be listed in a metric size. So for example, you could also try searching the net for sprocket with a 4 on 95.25mm. bolt patern, instead of 4 on 3-3/4"...

You could check out the sprockets at this site: http://gokartgalaxy.com/sprockets-and-sprocket-hubs.html

If you cant find your bolt patern, you could always order a sprocket blank and drill it to perfectly match your hubs patern.

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PS:
You probably already know this, but just in case:

The bolt patern of most (but not all) sprockets sold online, are measured using the Bolt-Circle patern method like this pic ilistrates.

 

[williag]

Didnt think about Metric, but i'll give that a look. What is the proper procedure for drilling the bolt pattern in perfectly centered? My biggest concern is getting it 1/8" off center and the problems that would cause.

 

[TT540]

I find it best to use a printed template, then a punch to score it then a small drill to start the hole, then the final bit size in a drill press. The blank sprocket will already have the center hole drilled. So the rotation will be good. Even if you have to file an attaching hole some, it won't make the assembly wobble or be out of round. Worse case you need a washer between the bolt head and a buggered hole.

 

[anderkart]

What is the proper procedure for drilling the bolt pattern in perfectly centered? My biggest concern is getting it 1/8" off center and the problems that would cause.

That depends; It might be easy to perfectly center the sprocket, if the center hole of your hubs bearing is exactly 1".

Those sprocket blanks come with a 1" center hole, what diameter is the center hole of your hubs bearing?

 

[williag]

3/4" shaft

 

[anderkart]

Then you could buy a 3/4 ID. X 1" OD. steel sleeve like this:
https://www.homedepot.com/p/The-Hil...PIPHorizontal2_rr-_-204724815-_-204726191-_-N

I'd cut that sleeve down to the exact same length as the thickness of your sprocket, and install it as an adapter in-between the 3/4" shaft and the sprockets center hole. That should perfectly center the sprocket to mark the 4 drill holes in your sprocket. Then simply leave that steel sleeve in place permanently, to help those 4 retaining bolts keep the sprocket permanently centered.