30 series torque converter questions

[TheDADgineer]

I did some digging in the post history but couldn't come up with the exact solution im looking for. So apologies if this has been covered many times before...

I'm building a kart from scratch (cannibal kart in more builds). I've been trying to work out the best drive setup. I've got an 8hp honda engine (3600 rpm max), 11" tall rear tires and solid rear axle.

I'm looking at the 30 series torque converter from Moosun, as it comes with 1" primary drive, and 10T #40 final drive sprocket. I'm not sure what reduction the torque converter has..

I'm hoping to keep the top speed quite low as this is for my young kids. ~20 mph top speed.

1) what size axle sprocket would you recommend with this setup? 42T? Or roughly in that range.

2) is there any real difference in quality between moosun and brave? Or other budget brands?

3) is it possible to govern top speed with a torque converter installed? As long as you keep above the engagement rpm?

4) last one. How difficult is it to install a torque converter? Is a separate mount required to support he jackshaft?

Thanks everyone!

 

[landuse]

Welcome!

1. I would not get a 42T sprocket. That would give you a very high gear ratio of 4.2:1, which means that you will have a high top speed but will take a while getting there. If you want to go about 20mph, I would rather get a 60/72T sprocket to slow you down some. You will have more torque though.
2. All those clone TC's are about the same. We haven't ever seen any real issues with them. Just make sure you get a genuine Comet belt though, the ones that come with these kits last 2 seconds
3. Govern using gearing. It is a much better way to do it
4. They are relatively easy to install. There are also several YouTube vids that would do just fine if you want to see how to install one.

 

[itsid]

I would add to
3. https://www.gokartsupply.com/speedr.htm

it's a expansion limiting weightpack for the series 20 and 30 TCs.. it can set the max high ratio the TC will be able to shift to
and thus top speed w/o altering the gear ratio.
pop the driver open, adjust the nuts, close back up and there: new different top speed.

42T sounds kinda alright for a lightweight kart on small wheels powered by an 8 horse.
but keep in mind, that the lower the ratio is, the snappier the kart will accelerate (which is actually more fun than a high top speed IYAM)
So I'd suggest a 48 T

'sid

 

[TheDADgineer]

Thanks itsid and landuse! Very helpful info guys.

Im going to go with a larger rear sprocket to get the torque and lower speed, most likely in the 54 to 60 tooth range. I'd rather it be slow and safe. The kids can always change the sprocket down the road when they feel the need for speed.

Itsid, thanks for the tip on the weight pack. I'll be looking into that if I need to slow the kart down any further.

I've been doing a little more reading on the torque converter and I understand it a bit better now. The ratio starts out at roughly 3:1 under low throttle then gets to approx 1:1 under full throttle. Which would yield a pretty high top speed. Once again, im deciding to limit the speed with a smaller sprocket.

Thanks again guys! I ordered the moosun TC so hopefully its decent quality. Take care


Edit: I meant to say once again I'm deciding to limit the speed with a LARGER sprocket.

 

[itsid]

series 30 2.7:1 in low and 0.9:1 in highest gear (and yes that does make a noteworthy difference
Anyways.. yeah... LARGER sprocket -> LOWER gearing [I saw your edit]

with the limiting weight pack you can control that 0.9 part to stop at 1:1 or 1.1:1 or 1.25:1 or whatever you want almost (I think it's adjustable up to almost 2:1) very handy for a kart meant for kids really,
since they grow and learn quick and it let's you adjust the top speed basically on a weekly basis without having to constantly buy new sprockets

'sid

 

[TheDADgineer]

That weight pack sounds like a really nifty bolt on item! I think I'll end up going that route, and saving money on sprockets as you mentioned. The easy adjustability is very enticing.

For now, I've still got to finish welding the frame and cage. I'm hoping to be mounting the engine and torque converter sometime in the coming weeks. Then finally some test driving provided we don't have too much snow by then (Canada eh)

Thanks again for all the help! I'm sure I'll be back with more questions in the future...