Which Torque Converter for Utility Vehicle Build

[Busman]

Staring to cobble together a Utility vehicle for myself and the grandson to cruise around the back 40. My question is about which would be the correct torque converter to use in this application. The dimensions will be close to that of the old style John Deere Gator (just no body).
96 inches long. approx 70 inch wheelbase. 48 inches rear tread centres. With 2 adults, approx gross weight will be anywhere from 800 to 1000 lbs.
Rear wheels are 14 inch rims with 175/65R14 tires, with outside diameter of approx 22 inches. Fronts are 16 x 5.00-8.
To start off with, will be using a Honda GX390 for power because I have it kicking around.

From what I've been able to glean from the internet, you tube etc..... I would require at least a 40 series torque converter. Maybe bigger?
Also need to know what sprocket size to use on the 1 inch live axle.
I am envisioning using some sort of jack shaft for the driven pulley and then onto chain to axle.

Just to be clear this is going to be a slow moving, 10-15 mph max. utility vehicle for cruising the back acres. All flat land, no hills to climb.
Counting on the knowledge from the forum folks here to advise me on which specific torque converter ( drive and driven ), which size belt, and sprocket size to enable this buggy to move around. Attached a couple of pics for reference.

Thanks in advance.

 

[karl]

Do you want reverse?

Anyway, to achieve your speed goal, with 23in tires, it will require a gear ratio of approximately 15 to 1.

This will require a jackshaft to offer compound gear reduction, as a 150 tooth #40 sprocket will hamper ground clearance.

With said ideal gear ratio, a 30 series should do just fine, with the benefit of being able to mount a cheap FNR box intended
for china buggys. To use the 40 series with the box, in the correct orientation that is, is a difficult task, I can explain if needed.

Most run into issues burning belts on big blocks with 30 series because of their gear ratios, wanting to go 50+mph.

 

[Karttekk]

As a rule, 30 Series torque converters are god for engines up to 8 HP, anything over that should require a 40 Series torque converter.

small-engine-projects.com

This domain may be for sale!

www.small-engine-projects.com

 

[karl]

As a rule, 30 Series torque converters are god for engines up to 8 HP, anything over that should require a 40 Series torque converter.

Yes this is common knowledge. Did you understand my post, or the original? You picked up on the fact he wants to do 15mph on flat ground?

 

[Karttekk]

"From what I've been able to glean from the internet, you tube etc..... I would require at least a 40 series torque converter."

Just reiterating he would need the 40 Series torque converter, that's all.

Thanks

 

[karl]

Just reiterating he would need the 40 Series torque converter, that's all.

Thanks

I can explain. The 8hp rating is a generalization, rough guide. Much more is involved with determining the suitability of a clutch
for a vehicle.

Forget about horsepower for a moment.

What matters to the cvt is the amount of torque being transferred through it.

No matter what the final gear ratio, the engine is still running 3600rpm likley, at full throttle *theoretically

What does change with the gear ratio is the amount of torque that the belt has to transfer.
This is what matters if you want the clutch to last.

That is why a V-twin riding tractor can use a 1/2 belt with a 20+hp twin engine, the final drive ratio is adequate,
so it can tow a big load without burning up the belt.

Similar to how a 420cc snow thrower can drive the auger with a 1/2 V belt.

 

[Busman]

Do you want reverse?

With said ideal gear ratio, a 30 series should do just fine, with the benefit of being able to mount a cheap FNR box intended
for china buggys.

Yes...reverse would be nice. I am not at all knowledgable about these FNR gearbox for china buggy ?????
Can you explain in a little more detail, and where this would locate in relation to the live axle, and where to find these gearboxes.
Thx.

Anyway, to achieve your speed goal, with 23in tires, it will require a gear ratio of approximately 15 to 1.

This will require a jackshaft to offer compound gear reduction, as a 150 tooth #40 sprocket will hamper ground clearance.

OK....so let's see if I understand this correctly. From the driven pulley I would be stepping down to a sprocket on a separate jackshaft and then from that sprocket on that jackshaft, stepping down again to the sprocket on the live axle? Or no?
I'm usually better with pictures... lol... send me a pic of what it is supposed to look like.
...... and a 30 series torque converter would be adequate for my purposes? The TAV 2 kit will work?
Thx.

 

[karl]

Yes...reverse would be nice. I am not at all knowledgable about these FNR gearbox for china buggy ?????
Can you explain in a little more detail, and where this would locate in relation to the live axle, and where to find these gearboxes.
Thx.

No problem. You want to mount the driven clutch directly to the input of said gearbox,
and the gearbox output shaft will have a sprocket on it, that can be coupled the the input of your jackshaft.
If mounted in later down the line, it will rotate slower, but have more torque going thru it, that can break it.


It would go,
Motor to jackshaft in,
Jackshaft out to axle sprocket.

Assuming you use the 30 series with a backplate built in. The FNR is the same concept as the backplate.

Without a backplate or FNR, two jackshafts will be needed, one for the clutch, one for extra reduction.

https://www.gopowersports.com/reverse-kit/

https://www.ebay.com/itm/Go-Kart-Re...531175?hash=item2af2498627:g:i3UAAOSw8NtfneRU

OK....so let's see if I understand this correctly. From the driven pulley I would be stepping down to a sprocket on a separate jackshaft and then from that sprocket on that jackshaft, stepping down again to the sprocket on the live axle? Or no?

Yep, as long as its geared for a slow top speed, the 30 series is fine. If you want over 15 or 20mph, 40 series sounds better.
But no widely available FNR box exists for such setup.

Any way this should help, shoot for 15 to 1 or steeper.

https://www.bmikarts.com/Go-Kart-Gear-Ratio-Calculator-Jackshaft-Setup

 

[Busman]

No problem. You want to mount the driven clutch directly to the input of said gearbox,
and the gearbox output shaft will have a sprocket on it, that can be coupled the the input of your jackshaft.
If mounted in later down the line, it will rotate slower, but have more torque going thru it, that can break it.


It would go,
Motor to jackshaft in,
Jackshaft out to axle sprocket.

Assuming you use the 30 series with a backplate built in. The FNR is the same concept as the backplate.

Without a backplate or FNR, two jackshafts will be needed, one for the clutch, one for extra reduction.

https://www.gopowersports.com/reverse-kit/

https://www.ebay.com/itm/Go-Kart-Re...531175?hash=item2af2498627:g:i3UAAOSw8NtfneRU

Thanks for explaining the workings of the gearbox and how it applies. More stuff to consider and add to the buggy.
Only problem with being in Canada, by the time you pay the exchange rate and shipping, border duties....you've almost doubled the price of these goodies.

 

[karl]

Thanks for explaining the workings of the gearbox and how it applies. More stuff to consider and add to the buggy.
Only problem with being in Canada, by the time you pay the exchange rate and shipping, border duties....you've almost doubled the price of these goodies.

I did not see that, bummer. But if you pick up the TAV2 kit, make sure it's the right bore for the motor.
Usually the whole kit is cheaper than buying just the driven, driver, and belt separate, with no backplate.

Then later adding the FNR box is an option.

 

[Busman]

Being new to the kart world and torque converters. Here is a question I have. Currently building a utility buggy for me and the grandson.
Looking at installing a genuine Comet TAV2 30 series #218355A with 1" bore. Are these Comets really worth the extra dollars? Seems like they are harder and harder to find, and many vendors don't seem to stock them anymore. Why is this?
I can buy a NOS Comet #218355A for about $130 USD. (I am in Canada). Been sitting on a shelf for many many years.
Worth buying? Or cheap out on clone? Is Comet quality that much of a stand out from the replacements?

 

[itsid]

the cheap clones you find on ebay and such are actually really durable I'm afraid,
I can only remember a single complaint in IDK how many years..

ONE exception: the belts!
on cheap clones the belt may be a bit sketchy at times and won't last as long as an original comet belt would.
in that case you can just buy a good quality (say an original comet) belt and install it on your chinese clone Tavkit w/o a problem.

'sid

PS that's actually kindof the same question you asked before.. so threads merged!