36 tooth rear sprocket, how bad is that?

[dwcopple]

So the kart project I have has a welded 36 tooth rear sprocket, what will this be like if I use a 10 tooth #35 centrifugal clutch on a 5hp Briggs? Should I look for a 60 tooth that I can bolt or weld to the 36 tooth instead? The axle is not keyed and is solid stock


or I could run this jackshaft setup and down(?)size the front pulley on the crank of the engine and ditch the cent clutch idea


thoughts???

 

[firemanjim]

No belt clutch..... ! Use a cent clutch, build a jackshaft to get around the axle sprocket being given welded on. Give me a second and ill tell you what you need to get to 6:1....
Wait, what size ate those tires?

 

[firemanjim]

Try 12 tooth clutch, 18tooth in,9tooth out, then 36 on the axle.... Gives you 6:1.....

 

[dwcopple]

why is 6:1 so necessary anyways? would a 3.6:1 not give me any takeoff power or something? I calculate a 36 rear sprocket giving me around 16-17MPH more than a 60T rear would

 

[OzFab]

would a 3.6:1 not give me any takeoff power or something?

Correct; you may end up with a massive top speed but, you'll destroy the clutch before it moves...

I calculate a 36 rear sprocket giving me around 16-17MPH more than a 60T rear would

You did something wrong because, at 3600rpm on 12" tyres, I get 36mph

 

[landuse]

What they said /\

You still haven't given us your rear tyre diameter. If it is too large, you might need lower than 6:1, like maybe 7 or 8:1

 

[dwcopple]

11"

 

[firemanjim]

You can get away with maybe a 4.8:1 or 5.2:1, but that would be as high as I would go.... MAYBE 4.2:1 if your engine is pumping out lots of hp..... Meaning NOT stock.....

 

[dwcopple]

I think I am just gonna buy a 60tooth #35 sprocket and bolt it to the 36tooth sprocket rather than mess with buying crap for a jackshaft setup.

 

[firemanjim]

Well I hope you get it centered perfectly.... If not, you're gonna have the wobbles......

 

[landuse]

Well I hope you get it centered perfectly.... If not, you're gonna have the wobbles......

X 10 on that. Even a millimeter off and you might have problems. How are you going to center it?

 

[dwcopple]

template with 3/4 bore placed over the axle onto the welded sprocket. Made a template on CAD program. Should be perfect. Sprocket is already drilled for 2-7/8" bolt pattern.

 

[firemanjim]

Post pics or video.....
Why not just use the jack shaft you have already, and swap out the pulley for the correct sprocket? Will that not work for you? It also allows you to play with ratios a lot easier (cheaper) till you find what you really like.....

 

[dwcopple]

yeah, that jackshaft is waaaaay to narrow to reach where the rear sprocket it and where the clutch sprocket will be. Not gonna work at all.
Is there not a readily available 60 tooth sprocket that is welded to a 3/4 bore hub anywhere? They seem to be unobtanium

 

[firemanjim]

Use the housing and add an axle that would be long enough. If needed, add one more bearing on one side to support excessive over hang. That would be my way of doing it..... Should be straightforward and simple enough, which kinda reads "cheap".....

 

[dwcopple]

except I'd have to buy another axle, a bearing and support, a clutch, more chain, and another sprocket too. My way, all I need is the clutch and the sprocket. Muey Bueno

 

[firemanjim]

except I'd have to buy another axle, a bearing and support, a clutch, more chain, and another sprocket too. My way, all I need is the clutch and the sprocket. Muey Bueno

Question.... Is that the right rear or left rear (standing behind kart) that the sprocket is next to?

 

[dwcopple]

either or, I flipped it. Just unbolt the bearing blocks and swap sides

 

[anderkart]

Is there not a readily available 60 tooth sprocket that is welded to a 3/4 bore hub anywhere? They seem to be unobtanium

Here's a 60-tooth, #35-pitch sprocket & hub you could drill/bolt to your old 36-tooth:
http://www.mfgsupply.com/gomini/gominisprockets/gominisprocketssteel35/4-469.html
http://www.mfgsupply.com/az2568.html

 

[Scout]

why is 6:1 so necessary anyways? would a 3.6:1 not give me any takeoff power or something? I calculate a 36 rear sprocket giving me around 16-17MPH more than a 60T rear would

My kart is 7:1 and I was getting 18 mph on a stock governed flathead. Same gearing on an ungoverned predator gets me 34 mph.