Torque converter

[SalCall1]

Very new to the gokart forum. I need to change out the centrifugal clutch for a torque converter. My kids are little and will be driving mostly in yards. How do I know I which one to get? I have an off road vehicle store to consult with, but I'd rather walk in with some knowledge. Thank you! Here are a couple pictures...

 

[SalCall1]

Side view

Side view

 

[firemanjim]

Rather than getting a TC, why not build a jack shaft? It will slow them down, and give them the torque they need to keep from getting stuck. Once they get a little older or just want more speed, then you can cheaply change out the smaller sprockets, to get a better top end speed.
You can only limit an engines rpm to just over that of clutch lock up, or you risk drastically diminishing the life of the clutch.
Getting a TC will give you more torque AND more top end...... How little is little, referring to your kids?

 

[SalCall1]

They are 8 and 10. The cart is pretty small but they can easily sit side by side in it...

 

[SalCall1]

I don't know what a jack shaft is..

 

[firemanjim]

I don't know what a jack shaft is..

http://www.bmikarts.com/Jackshaft-Kit-for-Mini-Bike-or-Go-Kart_p_1048.html
Like that...... They have other types. I'll get some links for you in a second..

 

[OzFab]

Have a read through this, mainly the last section under the heading "What is a jackshaft?"...

 

[SalCall1]

Now I understand more about jack shafts and I know more about my cart. It has a 6:1 gear ratio, 13 inch rear tires, and a 6.5 hp motor. It also has a burned up clutch I think. My kids will mainly be cruising paved roads or grassy yards, carrying less than 200 pounds and going between 5 and 15 mph. Should I just replace the clutch, replace it with a torque converter, or use a Tc and a jack shaft? I understand now what it does, but am still not sure if I need it.. Your help has been amazing. Thank you!

 

[firemanjim]

I would go with a jack shaft, personally. You can control what their top speed will be, even at WOT..... The only down side to that is the amount of torque they end up with. If you gear it for a top speed of 15mph, they will be blazing new trails where ever they want to go. Shouldn't get stuck anywhere......
On a side note, they sell remote engine shut offs that allow you to kill the engine from up to 250 feet away. With young Drivers, this could possibly save a lot of headache/heartache........

 

[SalCall1]

Thanks again! So just to be clear, I could replace the clutch and add a jack shaft and skip the Tc?

 

[firemanjim]

You might not even need to replace the clutch. Get the jack shaft and set it up. See how the clutch acts, with the new gear ratio. You are taking a serious load off of it, and I imagine it will still work just fine. I've abused a lot of clutches. You REALLY got to get it hot, to glaze it over and render it useless..... You can always buy a new one if you have to, but I'd stick with your current one unless it shows signs that it's TOAST..... Pull the bell off. Look at the shoes and spring. Look good? Then put it back together and keep going......
What are the tooth counts you currently have? I'll tell you what other 2 to get to get you the top speed you want. Oh, I need the tire height too....
EDIT
http://gokartsusa.com/Jackshaft-Kit-Gokart-Minibike.aspx
Even though it's about the same as a TC, I'd go with one like this because it makes installation much easier. And you can cheaply change gear ratios, down the road.

 

[firemanjim]

Double post..... I know I know......
Hey, gonna assume some things. Assuming you have 10 tooth clutch and 72 tooth axle sprockets, and a 15" tall tire....... Using that kit with the sprockets supplied (10 & 17) , you end up with a 12.24:1 ratio and a top speed of 13mph...... And enough torque to dredge through a mild mud hole or ditch.....
That's a live axle kart, right?

 

[SalCall1]

It's 60 and 10 for the axle and clutch and 13 inch wheels. I will go take a look at the clutch again!

 

[firemanjim]

Ok, well then the gear ratio would end up at 10.2:1 with a top speed of 14mph, on a 13" tall tire.
Later, you can change the 10 tooth sprocket to a 16, giving you a top speed of 22mph @ 6.3:1..... Or an 18 tooth, giving you a top speed of 25 @ 5.6:1.....

 

[OzFab]

By that stage, why would he not simply remove the jackshaft & run from clutch to axle?

 

[firemanjim]

By that stage, why would he not simply remove the jackshaft & run from clutch to axle?

I thought about that...... But I'd leave it (jack shaft ) in case more younger/inexperienced drivers come along. It would be easier to go back to slow...... Nieces, nephews..... Ect.....

 

[chancer]

Double post..... I know I know......
Hey, gonna assume some things. Assuming you have 10 tooth clutch and 72 tooth axle sprockets, and a 15" tall tire....... Using that kit with the sprockets supplied (10 & 17) , you end up with a 12.24:1 ratio and a top speed of 13mph...... And enough torque to dredge through a mild mud hole or ditch.....
That's a live axle kart, right?

12:1, will lower the top speed to child safe top speed. But all the torque causes tire spin. fun? yes! but not so easy for an 8 yr old to drive. On hard pack that thing will be sideways in a heart beat won't it?

 

[firemanjim]

12:1, will lower the top speed to child safe top speed. But all the torque causes tire spin. fun? yes! but not so easy for an 8 yr old to drive. On hard pack that thing will be sideways in a heart beat won't it?

No, because it's the speed of the tire spinning, that gets you side ways. How many 15mph burnouts have you seen? think about drifting.... It will end up with enough torque to pull a car. Seriously, they COULD drive straight into a tree, and walk up it, if they don't let off the throttle.
At a 12:1 on 13's, it would have enough torque to pull a lot more weight than the kart was designed for. Probably at least 3 times the weight, with ease.. He could pull a small trailer/Wagon with more kids in it. Even at 10.2:1, he is gonna have the power to pull a kid wagon......

 

[SalCall1]

You have given me some great info. I feel much better informed about my options and I'll let you know how it works out. And totally off topic, the sal is for Sally, so I'm not a he and the cart is for my daughters..

 

[firemanjim]

Well that's AWESOME! A mom working on a kart..... Keep on keeping on, then......
Whether you're male or female (or child) , we try to give the best advice possible. Explain your options for you... I hope it works out for you, and you nd the girls enjoy your new hobby. If it goes as planned (by the go kart gods) you will get hooked on driving a kart too. And that's how the collection of karts gets started.....