1" bore clutch $100...WHOA!!!

[Agent_Orange]

thoughts...

16T on PTO, 18T in JS, 11T out JS on clutch, 60T axle drive = 6.1:1
(average cruising numbers)

0r

16T on PTO, 11T in JS, 11T out JS on clutch, 60T axle drive = 4.2:1
(should launch with those numbers but red line at the speed of smell, right)

the track circumfrence is 39"

 

[landuse]

The second option is terrible!! That gives you a really high ratio. Not only will our clutch get fried, but you don't move very well. Go with the first.

I cannot remember, what was the tyre diameter. If it is above 14", then you should gear lower than 6:1

 

[Agent_Orange]

The second option is terrible!! That gives you a really high ratio. Not only will our clutch get fried, but you don't move very well. Go with the first.

I cannot remember, what was the tyre diameter. If it is above 14", then you should gear lower than 6:1

well in this specific case the "tyre" diameter would be 39 inches total. it's a track that rotates around a set of 7" drive cogs and a 6" idler wheels.

thanks for the advice

what would be a good ratio to shoot for a fast launch, high torque, slow speed sled. working with a 4HP Tecumseh and a 39" rear drive. with a 7" rear drive cog. stick with the 6:1 range?

 

[OzFab]

well in this specific case the "tyre" diameter would be 39 inches total.

The overall size of the track is irrelevant, the size of the drive roller is the important part...

7" drive cogs and a 6" idler wheels.

...& that's what concerns me, even a #35 60t sprocket is larger than 7", you'll need to work on a sprocket smaller than the drive roller (see my comments in your build log)

what would be a good ratio to shoot for a fast launch, high torque, slow speed sled. working with a 4HP Tecumseh and a 39" rear drive. with a 7" rear drive cog. stick with the 6:1 range?

The higher the number the better it will be.

Since you're working on a 7" drive roller, 6:1 will be fine, loads of torque & a top speed of a blistering 12mph

 

[Agent_Orange]

The overall size of the track is irrelevant, the size of the drive roller is the important part...



...& that's what concerns me, even a #35 60t sprocket is larger than 7", you'll need to work on a sprocket smaller than the drive roller (see my comments in your build log)



The higher the number the better it will be.

Since you're working on a 7" drive roller, 6:1 will be fine, loads of torque & a top speed of a blistering 12mph

got a better ratio that might give some more get up n go? 12 is rather ... lame...

 

[OzFab]

For a "typical" 6yo girl, that's really fast. My daughters kart does the same (calculated) speed, she's now 9 & hasn't asked me to make it faster yet...

5:1 will give you 15mph@3600rpm

 

[Scout]

got a better ratio that might give some more get up n go? 12 is rather ... lame...

yeah, but, the ratio will make it take off fast, but top speed won't be much as posted. You can change it to 5:1 and get a bit more top speed, but not as much acceleration. Or run a torque converter.

 

[firemanjim]

I gotta say, 12mph IS fast for a six year old. Picture this..... she is out near the end of the "bend" where you turn to head back. The throttle sticks open , shes 50 yards from you..... you gonna run the 24mph+ for 50 yards to catch up to her?
Stick with low end stump pulling power so she NEVER gets stuck and gets used to the "blistering speed". THEN swap out and get more top end , when she knows how to keep from getting stuck..... You dont give a rookie a 150psi charged 3" line right off the bat. You give him a 1&1/2" line pumped to 100 psi...... And laugh at what ensues when you play with the psi......

 

[Agent_Orange]

between Grainger, go kart suppliers and McMaster-Carr I got a eye on a set up that will get me about a 5.5ish:1 ratio