Centrifugal Clutch Matching

[hollyjotopor]

I work at an Outdoor Power Equipment repair shop. Occasionally we repair Go Karts and things like that. My question is, if someone calls (I know the basics but really not much about Go Karts) or comes in and wants me to tell them what size clutch, chain, etc. they need, how do I figure that stuff out? Like today, I had a customer call and needed a clutch and a chain. They had a 52 tooth sprocket, and that is it. So how do I figure not only that out, but the size of the chain if they bring in a clutch or other parts? Any help and "schoolin" you can give me would be great and greatly, greatly, appreciated!! Thanks a bunch!

 

[itsid]

tooth to tooth distance of the sprocket gets you the chain size (more or less)
if it's 3/8" it's a #35 chain if it's 1/2" it's either #41 or #40
#41 is narrow chain light duty.. so if the kart looks big'ish or heavy it's #40
if it's an engine much more powerfull than let's say 5-6HP it's most likely #40

ideal ratio is 6:1 for most karts...(what we advice to start with)
smallest* toothcount for clutches is 12 for #35 and 10 for #40
(there are smaller toothcounts with some trickery.. but that gets very expensive very soon.. so just keep 12 and 10 in mind)

with the toothcount and chainsize the most important number is bore size.
clutches come commonly for 3/4" and 1" bore (straight keyed PTO)

with that you should be able to cover roughly 90% of US based fun karts.

'sid

 

[Poboy kartman]

'Sid pretty much covered it....except. ...check out the gear ratio calculator thread here....it will tell you how to get to 6:1.....

 

[landuse]

Tyre size also has an influence on gearing. 6:1 is a GREAT starting point, but as soon as you get back wheels above about 15", you should look to gear lower at maybe 7 or 8:1

 

[hollyjotopor]

Thank you so much guys! I have been trying to get help on this forever, and I need to be able to tell my customers something!!

Poboy, You didn't include a link for the gear ratio calculator, could you tell me how to get there?

 

[Poboy kartman]

Thank you so much guys! I have been trying to get help on this forever, and I need to be able to tell my customers something!!

Poboy, You didn't include a link for the gear ratio calculator, could you tell me how to get there?

Yes.....I don't do links with this phone. .....I guess I'm just an idiot. ....can't seem to figure out how. .....

Anyway. .....scroll up to the top and click on the first break-down. .....in other words. ....DIY gokart forum. ......then all the sub-categories will come up. .....click on FAQ and articles. .....and you should find the thread......

 

[itsid]

huh?

what's there to calculate???

6:1 ratio means six times the teeth on the axle as there are on the clutch.

you know one number (say axle sprocket has 72 T) then divide by six and you'll get 12T for the clutch.

you have a 14T clutch, multiply by six and you end up with a 84T axle sprocket

it's that easy...

True, sometimes you cannot get a 6:1 ratio, sometimes you do not NEED a 6:1 ratio (but more, or on very few occasions less)
but that cannot be told by a calculator yet anyways.

Just one thing..
if there is a jackshaft involved, then you need to make sure you get the ratio right; or it'll be very confusing.

here it goes:
(Jackshaft in / clutch) * (axle / jackshaft out)
say 30 T on the axle and the jackshaft has 24T in and 10T out
(yeah easy numbers.. but you get the idea)

then you know the last part is 30/10 (3:1) and your target is again 6:1
6/3 is two; your JS in is 24, divided by two that's again 12T for the clutch
to end up with 24/12*30/10 = 6 (and you have the 6:1 ratio)

'sid

 

[landuse]

Thank you so much guys! I have been trying to get help on this forever, and I need to be able to tell my customers something!!

Poboy, You didn't include a link for the gear ratio calculator, could you tell me how to get there?

Have a look at THIS thread for all sorts of calculators, info, etc

http://www.diygokarts.com/vb/showthread.php?t=10036