Newbie Clutch question

[ralthoff]

I am building my little brother his first go-kart and have a quick question. I acquired a B&S 3.5 hp engine for free, and it works great, but it does not have a keyway slot on the shaft. Do I need a keyway slot? I am looking at clutches and they talk about keyway types and I don't want to waste my money on something that will not work. Thanks in advance for the help.

Reece

 

[EagleTalons]

You need to take that engine to a machine shop and get a keyway cut into the shaft. The keyway "hooks" the clutch to the shaft so it will spin.

You could cut one yourself with a dremel or buy a crankshaft with a keyway.

 

[Affair_driven]

Is it a horizontal or vertical shaft configuration?

 

[mike75925]

sometimes when a key shears it will make it look like there is no key way.

 

[EagleTalons]

Pictures would be nice.

 

[Kaptain Krunch]

I dont think i have ever seen an engine without some sort of keyway? is it tapered shaft? pictures...

 

[ralthoff]

 

[ralthoff]

sorry for the size, I didnt have time to change it. It is a 3/4 inch shaft, btw

 

[Affair_driven]

External threads throw me off.
What was this powering?

 

[ralthoff]

it was powering a water pump for my neighbors pressure washing business.

 

[Affair_driven]

Typical usable kart engines have a 5/8" or 3/4" shaft with a 5/16 x24 internal thread along with a 3/16" keyway that runs the length of shaft.
Shaft does not appear to be long enough to support a centrifugal clutch. Need at least 2 1/4" in usable length.

 

[ralthoff]

how wide are clutches?

 

[ralthoff]

i just measure the shaft and it is over 2 1/4 inches long (about 2 3/8)

 

[Affair_driven]

Straight through clutch is what you will need. They are also known as 'bi-directional'.
Max-Torque makes good ones.
Try to test fit one before purchase.
The lack of a keyway complicates things.

 

[ralthoff]

I think my neighbors company has a mill that can cut a keyway, or is that a bad idea?

 

[ralthoff]

http://www.gokartsupply.com/clutches.htm

I feel even more retarded, whats the difference between keyway and built in key? (maybe I am just thinking too hard on this, my brain is fried after a long day)

 

[Kaptain Krunch]

If you could get the crank machined that would be the way to go.

 

[mike75925]

keyway is the place for a key, built in key means less parts because the key is made to the attachment(clutch, pump, whatever). either way the shaft should have a keyway.