Torque Converter help

[RustyRedneck]

Hey guys, I'm working on an older home made go-kart that I acquired earlier this summer. It appears to be fairly heavy and I think the old 8 hp Briggs just might not be up to the task so I intend to put a 18 hp twin opposed on to push it around with me on it. I had noticed the Torque converter is not quite lined up. I believe this to be a 40 series Comet unit. My main question is, are both halves of the Torque converter supposed to be centered to each other? I did think to measure the center to center distance of the shafts and they appear to be 9.5 inches apart. Any help/advice is welcome. I have no prior experience with torque converters.

 

[bob58o]

Tell us the OD of the tires and the number of teeth on each of the sprockets.


This PDF has most of the info you'll need.
https://www.bmikarts.com/PDF/Comet_40series.pdf
It mentions a 3/8" offset, but I set mine so the belt is straight at idle. It is late and I'm not exactly sure what they are saying to offset.
???The inner edge of the inner sheave on the driver unit is offset 3/8" from the inner edge of the outer sheave on the driven unit???

The belt you have is for shaft (or pulley) center to center distance of 9-3/4"
203787 is for 9-3/8" center to center distance.
If your distance falls in between the two (if it is really 9.5"), you should get the larger belt. If it is 9.5", you have the correct belt - but it may be worn out and stretched.

 

[RustyRedneck]

My sprockets are 10 and 32. The 32 was one I had laying around. I had to build rear hubs and make a new axle. It didn't come with one when I got it. The rear tires are 22 inches tall. Came off a 4 wheeler.

 

[kevbo22]

10 and 32 teeth? You're going to need a much bigger rear sprocket. like 70-75 teeth.

 

[bob58o]

Yep, it may not be that the engine doesn't have it in it - It may be you didn't give it a chance.
With a 3.2 :1 Gear Ratio and 22" tires, you are geared for about 75mph at 3600 RPM.

I'd say even bigger than 75T
75T would put you around 30mph at 3600. That would be much better. But I think closer to 100T makes more sense. A 100T sprocket would put you around 25mph at 3600.

If you go with the 18HP engine, Then you might be able to get away with a 60T (but that is still kinda pushing it with 22's). 75T with the 18 HP would be plenty good.


So with the engine you have, I'd say at least 85T.
With the 18HP, I'd say at least 60T.

 

[RustyRedneck]

I've never actually had the engine that was on the kart running because it is missing the carburetor. I'm not quite done with the rear axle yet. Just kinda throwing it together. I figured the gear reduction and low-end power the torque converter would be able to deliver, I'd be able to at least try it. I know, I know, should've done the math first. Oh well. I guess I'll go shopping tomorrow and see if I can find a sprocket to run about 30-35. This is more of an off road kart. If I got the math right, a 65 tooth should get me close to 35 where my friends run theirs.

 

[bob58o]

For example, my 420cc buggy with 40 series TC and 18.5" Tires is geared 60:11.
That gearing gives me 36mph at 3600 RPM; 50 mph at 5000 RPM.

That is basically the same as your 65 :10 with 22's. Will be fine with the 18 horse. Likely not enough for the 8 horse. It will probably work for a while, but may cause premature belt and TC wear.

 

[RustyRedneck]

We'll just have to see what the local ag parts store has in stock. That's where I've sourced the shaft couplers for hub centers and the pillow block bearings. Lots of good stuff.

 

[RustyRedneck]

I've got a 70 tooth sprocket on order. Figured I could spin the engine a little faster if I can't keep up with my friends.