Clutch and tire size, please help!

[Rocklobster61]

Im getting a gokart with a 10 tooth clutch and does to a about 60 tooth gear, which drives the wheel. The tires are about 12 inches and i want to put 16 to 18 inch wheels on, i know it will slow it down but by how mutch and how mutch more tourqe will i get.

 

[Russ2251]

Use This Calculator

 

[Jcotz]

Depending on the engine/clutch setup, it will probably not be wise t put that large of tires on a kart with gearing that high. Please tell us your whole setup including weight, where you plan on driving it, and engine.

 

[landuse]

Im getting a gokart with a 10 tooth clutch and does to a about 60 tooth gear, which drives the wheel. The tires are about 12 inches and i want to put 16 to 18 inch wheels on, i know it will slow it down but by how mutch and how mutch more tourqe will i get.

When putting tyres that large on your kart, you are going to have to change your gearing. You have a 6:1 ratio at the moment with 12" tyres. When you increase tyre diameter so much, you are going to have to gear lower. Since you have a 10T clutch already, you cannot really change your gearing there. What you are going to have to do is get a bigger axle sprocket. I would suggest at least a 72T.

The problem is that sometimes larger axle sprockets cause clearance problems with the ground. If this is the case with you, you might have to invest in a jackshaft to get the same gearing you need, but with using smaller sprockets

 

[Rocklobster61]

So basicly saying i shouldnt put on bigger tires? How do i post pics?

 

[jman231994]

How to Post Pics:

http://www.diygokarts.com/vb/showthread.php?t=735

As for the tires, nobody is saying you shouldn't put bigger ones on. They would be fun and give a better ride off road, but in order to make up for the larger size, you would need a larger axle sprocket.

Otherwise you will just burn up the clutch and have really shocking acceleration, which at times can actually limit your top speed, if there isnt anywhere big enough to hit top speed then the lack of acceleration is useless.

As for the sprocket clearance issue, another way around it more or less is to have the sprocket right up against one of the tires, unless you slid off the edge of a sharp rock or something you will never hit the sprocket because its always at the same clearance as the tire.

 

[landuse]

Yup, nobody is saying you shouldn't put those tyres on. You just have to keep in mind that you will need to regear.

We will help you out when you get around to doing it though. You are definately going to lose speed doing the tyre swap though

 

[Rocklobster61]

What about to get more speed and tourque on a kart? I have a carterbros econo cart and it has preatty bad tourqe and alright speed about 25 mph.

 

[OzFab]

What size engine does it have?

 

[Blazkowiez]

With those tires you'll need a 72t sprocket for 16" tires. If you want 18-20 inch tall rear tires you'll need a jackshaft or torque converter.

 

[landuse]

What about to get more speed and tourque on a kart? I have a carterbros econo cart and it has preatty bad tourqe and alright speed about 25 mph.

There is always a trade off between torque and speed. Gearing for more torque gives you less speed, and visa versa. You cannot increase both. If you gear for meore torque on your kart, you are going to be going slower than 25mph

 

[OzFab]

You cannot increase both.

Yes you can; put a bigger engine on it

 

[landuse]

Yes you can; put a bigger engine on it

Ok, OK. We are talking about using tha same engine though

 

[jman231994]

You are definately going to lose speed doing the tyre swap though

Actually landuse, when you think about it, there shouldnt be a loss of speed. Now, I havent done any calculations or anything to back up my claim but I'm pretty sure that if its done right then there should be no speed loss.

When the tire size is increased the theoretical speed at the same rpm increases. Yea? And then the gear down to provide enough torque removes this speed. Wouldnt it sort of balance out?

Or does the force required to turn a wheel increase exponentially with increasing tyre diameter?

 

[Rocklobster61]

So what wouls be the best ratio for 15 inch wheels and a 10 tooth clutch?

 

[OzFab]

You might get away with 60t but you do better to go slightly higher, 66 or 72

 

[Rocklobster61]

Its a 7 hp tecumseh, so 10 toth clutch to 72 sprocket to 15 inch tire? Whats the best ratio for good tourque but good speed?

 

[Rocklobster61]

The caculator says when i run a 15 inch tire with a 60 tooth sprocket and a ten tooth clutch with 3600 rpm it would go 27mph, i know thats alright speed , but what about torque, would it be good on hills or not ?

 

[landuse]

The caculator says when i run a 15 inch tire with a 60 tooth sprocket and a ten tooth clutch with 3600 rpm it would go 27mph, i know thats alright speed , but what about torque, would it be good on hills or not ?

You will have a ratio of 6:1. 15" tyres could mean that your torque is not going to be that great

 

[jman231994]

Do you have any way of checking your rpm? If you cant get the torque you need whilst going fast enough your best option is to remove the governor, that way you can gear lower for the extra torque, but the increased rpm retains the speed you want