Newbie, looking to see what it will take to change to a torque converter

[BrianI]

Hi All,

This is my first post. And, this is my first go kart (since I was a kid). Now, I've got a couple of kids, and I went out and bought this cool little go kart. It just needed a clutch, but when I put it on, I realized just how little low-end torque there is (especially when I'm on it). I understand how the centrifugal clutch works, and accept that this is the best it can do with my predator 212 engine, so now I am considering switching to a torque converter.

I am new to go karts, but I am mechanically inclined, and enthusiastic to have this going by the spring. So I am looking for some advice. Most of the pictures that I've seen involve a sprocket mounted on the rear axle; is that necessary? If so, will I need to cut out the rear shaft to expose the axle, and buy a "Live" sprocket? Will the engine need to be more centered then, or can some kind of jack shaft do the job with the existing sprocket? These terms are all new to me, so if anyone can also educate me on terminology, it sure will help me with Google searches.

My goal is not to eek out the most speed from this kart, but I definitely would like it to operate decently in a field with a bit of slope.

Any advice would be appreciated!

-Brian




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[OLDKID]

Complete live axle kits are available along with torque conv. kits for the predator at go karts USA , or , DIY maybe SYCARMS ( on this forum )
Looks to me like you have to small a sprocket for that large of a tire - high gear ratio . Go karts are like potato chips, you can't just have one . One option would be to mount your engine higher 2x2 , or 2x3 square tubing and drill some holes . That would allow you to mount a larger dia wheel sprocket , longer chain for a lower gear ratio - more bottom end . Tools involved hacksaw / chopsaw , 3\8 drill bit . Then you can take your saved money and buy another kart with a live axle......and another.....and , you get it .
MO BUGGY!!!!
Oh , Welcome to the Site .

[OLDKID]

I just clicked on GOPOWERSPORTS (one of this sites supporters') and they are advertising a sale on both the axle , and T.C. kit right on the opening page .

[BrianI]

Thank you, OLDKID, what you said makes a lot of sense. I'd better maximize what I can out of this axle first.

Right now the gear ratio is 5 (i.e., 12 teeth on the clutch, 60 teeth on the wheel hub). With that, in the grass with a slight incline, I have to push the back tire with my hand to get it to move, but then obviously the clutch gets very hot and smokes off the gear oil I put on the clutch bearing. I weight like 200lbs, which probably doesn't help either. Once I make it to a level area, I pick up speed and it seems OK for a bit, but I can't live with it the way that it is.

So if I understand you right, I should have more teeth on the wheel hub sprocket? That would increase the gear ratio, right? Having ridden a ten speed before, I know that that certainly would help with the power at the bottom end. I've seen as high as 80 teeth so far, which would increase the gear ratio from 5 to 6.7. At this point, those are just numbers to me; I can't appreciate if that will be enough of an increase in torque at the low end or not. What do you think? And would you think I could find a sprocket with more than 80 teeth?

[BrianI]

This seems pretty reasonably priced at $16: http://www.ebay.com/itm/84-Tooth-219...3D252014686191

I would still have to buy the hub that it bolts to, such as: http://gokartsusa.com/sprockets-1.aspx for $27.

Think that's it? I mean besides the tubing to raise the engine, and the longer chain.

[BrianI]

You definitely put me on the right track, thank you. This page also helps a lot: http://gokartguru.com/blog/?p=226

The gear ratio made sense to me from the start, but I wouldn't have thought the tire-sprocket ratio would matter, actually.

So what I learned is that my goal should be 14:1 gear ratio or greater for my 19" tires, likely using a jack shaft.

[OLDKID]

Sycarms (supporting member/ vendor)or one of the other members could set you straight on ratio , I'd just be calculated guessing . As far as mounting your new sprocket goes since your going larger you could simply drill and bolt or tack weld it to your existing sprocket and compensate the side to side difference when you make up your new engine spacer/mounts . 10/4 ?

[OLDKID]

Hey , just had a thought , and thought It's worth mentioning . You mentioned helping it along with your hand . If your kids seen that you better have a sit down and lecture with them . God forbid , they could very easily lose a finger doing the same thing .

[BrianI]

Yeah, I agree with you: touching the tire is very stupid. But don't worry: my daughters didn't see me do it, and even if they did, they are too timid to consider doing something like that.

I like your suggestion about tack-welding the sprocket to the original sprocket.

[OLDKID]

I wasn't thinkin jackshaft , just nice n simple , looks like your clutch sprocket is close to wheel sprocket .... So raise ( spacers ) eng. up to clear larger sprocket you attach to old sprocket , install longer chain , $45 and two hours and away you go doin the one wheel peal ....up-hill .