off road go-kart gearing

[Redthemesetup]

Hi all, so I'm a complete newb to gearing and ratios. I'm building an off road go-kart and I have no idea how to properly gear it. I really don't want to spend money on a torque converter, so I am just going to use a clutch.I am using a honda GX270 with a 10t clutch. I will be going up hills but for the most part, it will be flat field

so what I'm getting at is, what gear ratio should I use for it? Thanks!

 

[chancer]

We need to know the rear tire height, to give you a good answer

 

[Redthemesetup]

sorry, rear tires are 16"

 

[chancer]

60 or 65 tooth.
60/10=6 6:1 gear ratio. and of course 65 would be 6.5:1

With a 5HP 6:1 is max for up to 15" tires or the clutch just burns up.

Since you have the gx270 6:1 with 16"s may be ok.

For safer more proven results go 6.5:1 or 7:1

 

[Kartorbust]

I'd lose the clutch and get a 40 series torque converter then run a 60 on the axle. The TC will give you the low end you need, and will allow you to go faster on the flat. A standard centrifugal clutch is only one speed.

A designer knows he has achieved perfection, not when there is nothing left to add, but when there is nothing left to take away.

 

[Redthemesetup]

I would get a TC but, I don't want to spend that much,especially because I live in Canada where everything is 3x as expensive as it is normally for right now at least

 

[Redthemesetup]

does anyone know where I can get a 65T sprocket that isn't quick change?

 

[Kartorbust]

So you want a sprocket that isn't a split. http://www.gokartsupply.com/sprocket.htm

A designer knows he has achieved perfection, not when there is nothing left to add, but when there is nothing left to take away.

 

[Redthemesetup]

but none of those are 65T

 

[Bbqjoe]

but none of those are 65T

I know!
Get a 70, and cut 5 teeth off.



Here's a blank.
http://www.jackssmallengines.com/ja...fgckcmqwyver8sa3kkeuukobux6yetaqhgaahfn8p8haq

And for just about double that price,here's a TC.
http://auto-express.co/products/go-...m=cpc&utm_source=googlepla&variant=4688379521

 

[Redthemesetup]

but the one you have linked is 75......

 

[Kartorbust]

5 extra teeth or 10 extra isn't the end of the world. All it does is slightly reduce your top speed, but increases toque to the wheels, thereby increasing acceleration out of the hole.

A designer knows he has achieved perfection, not when there is nothing left to add, but when there is nothing left to take away.

 

[chancer]

5 extra teeth or 10 extra isn't the end of the world. All it does is slightly reduce your top speed, but increases toque to the wheels, thereby increasing acceleration out of the hole.

This is partially true. But with the larger tires 16" requiring the 7:1 (ish) ratio to get moving, you do not lose to much on the top end. The taller tires make up for it.

There is a formula for final drive. I donot have it. But 6:1 will 13" tires would be a similar top speed as 7:1 with 16:" tires.

---------- Post added at 11:54 AM ---------- Previous post was at 11:52 AM ----------

Also here is a BIG list of Kart suppliers. One will have the sprocket you are looking for.
http://www.diygokarts.com/vb/showthread.php?t=1180

 

[Kartorbust]

Yeah doing 'Sid's calc. And guessing combined weight of 300lbs, he'd need a 75 tooth sprocket, to not burn the clutch out.

A designer knows he has achieved perfection, not when there is nothing left to add, but when there is nothing left to take away.

 

[chancer]

My opinion is that Sid generally and his Calc are very conservative when it comes to clutch gearing.

 

[Kartorbust]

It's a great baseline to work with, but better er on the side of caution jmo.

A designer knows he has achieved perfection, not when there is nothing left to add, but when there is nothing left to take away.

 

[Kartorbust]

Well this is the closest I can find. If you have a Princess Auto near by, they should have it. http://www.princessauto.com/en/detail/72-teeth-41-chain-weld-on-sprocket/A-p8609620e

If you want bolt holes drilled, you can do it in a drill press, or have a machine shop do it, since these are a harden steel variety as a lot of sprockets are.

A designer knows he has achieved perfection, not when there is nothing left to add, but when there is nothing left to take away.

 

[mckutzy]

This is a large sprocket... Just to let you know... It's 11.7"
I use one of these for my brake disc...
They can be drilled with standard drills, they aren't hard nor have hard teeth on these verity.
This style is designed for a weld on hub.

 

[Redthemesetup]

great, I think I'll go with the 72T sprocket from princess auto and then just remove the governer for the high end.

 

[chancer]

Just be sure to remove the entire Governor. Not just the linkages.
https://www.affordablegokarts.com/govenor-removal.php