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bocanegramusic 07-13-2015 08:29 AM

TC drive sprocket
My kart is made with a car differential. So the gearing is much lower. I'm trying to find a 17 tooth or 16 tooth drive sprocket to put on my torque converter so it will go 25 to 30 mph instead of its 12 to 15 right now. Any help is much appreciated.

itsid 07-13-2015 08:36 AM




bocanegramusic 07-13-2015 09:09 AM

Ok, I'll post pics, but I haven't takin pictures of the TC I installed. But you can get the idea with the centrifugal clutch still ya go

bocanegramusic 07-13-2015 09:15 AM

1 Attachment(s)
Cute huh

itsid 07-13-2015 11:01 AM

well, in fact ... No that didn't help at all :D

That's exactly the point, what TC is installed, what jackshaft does the sprocket have to fit,
is it on the same end as the driven, or on the opposite end.. etc.

that's all easier to determine with pics, and the reason I asked.

Oh, and judging by the pic and that a car axle itself isn't exactly the lightest diff you could find for a go kart...
I hope this is a 13-16hp engine, otherwise you might struggle to hit 20mph, no matter what gearing you drop in.


bocanegramusic 07-13-2015 11:22 AM

I see your point. Well it's a knock off comet. I'll get picture asap...bare with me 😉

bocanegramusic 07-13-2015 11:25 AM

Oh, and I have the 6.5 hp predator. This thing gets up to speed FAST! But only goes 12 to 15 mph. But believe me when I say it gets there in a hurry. So I'm hoping just changing the sprocket on the drive pulley on the torque converter from a 10 to a 16 or 17 tooth would greatly increase the speed.

itsid 07-13-2015 11:41 AM

do you happen to know the ratio of the diff you're using?

Since I seriously doubt that it will move at all if you install a 16T TC sprocket
that would nearly cancel out the tc-> diff reduction from now 2.3:1 to then only 1.4:1...
the internal diff reduction must be larger than 5:1 to cope with that.
And frankly I believe it's smaller than 4:1 (closer to three to one actually)

IDK since I can't identify the diff, but with the assumed weight and the wheelsize...
it's likely that you don't reach speed because you don't have the power to do so.

keep in mind, that the TC shifts only if the engine has the power to do so;
otherwise it'll be stuck in low gear providing torque, not speed ;)


bocanegramusic 07-13-2015 12:19 PM

Well, I had a centrifugal clutch on there and it was an 11 tooth and the sprocket on the diff is a 23 tooth. According to the math, with the wheel size and speed of motor. That kart should be going 100mph. (i put in the specs on a site and it gave me my speed) I have 20" tires.
So to be honost, I do not know the gearing for the diff...

colestreasures 07-13-2015 12:51 PM

Well i have never seen anything like that before, i don't even see how that centrifugal clutch can handle turning all that. :popcorn:

bocanegramusic 07-13-2015 12:53 PM

I had a friend look at it, says it might be a 5:1 differential. Only guesses considing he didn't take the plate off.

bocanegramusic 07-13-2015 12:55 PM

If it is 5 to 1, then that would explain going slow. Right?

itsid 07-13-2015 06:07 PM

if it IS 5:1 then you should be going 20 mph on 20" wheels.. if you're NOT, then it lacks power

if it lacks power, you can't install a bigger TC sprocket or you'll be ending up with an even slower kart.
you will only loose acceleration

if you misread your speedometer and you reach 20mph... and it IS a 5:1, then you should be able to install a 14T TC sprocket (not more I'd say)
which would result in ~30mph

I still don't know the weight of that contraption nor the diffs ratio of course;
so these are just guesses...

but even a 5:1 diff would not explain your current top speed of only 15mph ...
sooo lack of power is still my best guess for now I'm afraid.


Denny 07-13-2015 08:39 PM

That looks like a ez go golf cart rear. I believe they are around 6:1, it's been years since I had the cover off of one.


bocanegramusic 07-13-2015 08:57 PM

It's funny you should say golf kart rear end...i had been thinking that's what it was from beginning!

itsid 07-13-2015 09:07 PM

ez go.. then it'd be a dana diff, correct?

If that's the case, there should be a ratio marking on the bottom edge ;)


it just dawned on me... a 6.5HP??

does that mean you have a series30 TAV2 Kit??

If so, I'm afraid this will get very expensive very fast!

what you need is a 5/8" bore Type C sprocket with a keyway.
The only ones I KNOW ready for use are the original comet ones (10T for #40 and 12T for #35 chain)
Azusa offers type C engine sprockets with the same bore (IDK if they fit perfectly, depends on the width) but only up to 12 Teeth!

Sooo the only option that's left is find a blanket (say from
and have it machined for your TC, and that's not actually a cheap thing to do I guess...

with a series 40 TC or a series 30 with a home made jackshaft you might be able to use a B-Type sprocket if your jackshaft is set up for it.
that's much cheaper to find.

Oh.. may I ask why not change the sprocket on the differential? I have the feeling that'd be easier altogether...

Half-breeder 07-13-2015 10:08 PM

BMI has em.

bocanegramusic 07-13-2015 10:39 PM

I thought about the sprocket at the differential, but then I thought, I shouldn't go too small or it might break under I figured why not change tc sprocket 😓

bocanegramusic 07-13-2015 10:42 PM

3 Attachment(s)
Here are some pictures

bocanegramusic 07-13-2015 10:44 PM

Who is bmi?

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