Gear ratio formulation calculation for sprockets.

[flashbang]

Hi all,
Can't get my head around the calculation.

What I have.
Manco Fox Vortex cart.
Duromax 208
20 inch rear tires
Series 30 torque converter driven 6 inch.
60 tooth axle sprocket
9 tooth jack shaft sprocket.

I deleted the Jack shaft

Added a FNR transmission that has a:
Forward Ratio: 1:1.3
Reverse Ratio: 1:2.6
10 tooth jack sprocket.

So, the question is how to line the new gear ratio with the original sprocket ratio setup if I don't know what the ratio is?

If I'm correct the original ratio was 1:6.67 which did just fine.

The variable now has a 10 tooth jack sprocket but also the gear box has a reduction of 30%.

I got rear sprocket 60t/1.3 = 46.15, so that makes the rear sprocket 46t.

Jack sprocket 10/46 = 1:4.6 ratio plus 1.3= 1:5.44

Is this even close to right?

I was looking to get close to original ratio and even getting a 54t rear sprocket to add some top speed.

Jack sprocket 10/54 = 1:5.4 ratio plus 1.3= 1:7.02

TIA

 

[Denny]

The gear box has a slight overdrive. So if you keep the 60 tooth axle sprocket you should be good to go. It should be capable of speeds around 30. To use a gear calculator you would need to divide 60 by 1.3.

 

[BrownStainRacing]

Hi all,
Can't get my head around the calculation.

What I have.
Manco Fox Vortex cart.
Duromax 208
20 inch rear tires
Series 30 torque converter driven 6 inch.
60 tooth axle sprocket
9 tooth jack shaft sprocket.

I deleted the Jack shaft

Added a FNR transmission that has a:
Forward Ratio: 1:1.3
Reverse Ratio: 1:2.6
10 tooth jack sprocket.

So, the question is how to line the new gear ratio with the original sprocket ratio setup if I don't know what the ratio is?

If I'm correct the original ratio was 1:6.67 which did just fine.

The variable now has a 10 tooth jack sprocket but also the gear box has a reduction of 30%.

I got rear sprocket 60t/1.3 = 46.15, so that makes the rear sprocket 46t.

Jack sprocket 10/45 = 1:4.5 ratio plus 1.3= 1:5.8

Is this even close to right?

I was looking to get close to original ratio and even getting a 54t rear sprocket to add some top speed.

Jack sprocket 10/54 = 1:5.4 ratio plus 1.3= 1:6.7

TIA

5.4 x 1.3 = 7.02:1

A 30 series with 6" driven is 2.7:1 on the low side, and .9 when it goes into high.

2.7 x 1.3 x 5.4 = 18.95:1 on the low side.

.9 x 1.3 x 5.4 = 6.31:1 in high

A 30 series with a 7" driven is 3.13:1 in low, and 1.12:1 in high.

 

[Denny]

Either way, you should be near your target ratio of 5.45:1 for your final drive. Do not go to a 54 tooth axle sprocket or you’ll loose too much acceleration and risk burning up belts.

 

[panchothedog]

Why don't you just give it a try as is. You can always gear up or down from where you are now if you're not satisfied with the results.

 

[karte_m0lim]

go to http://app.kartcalc.net/#home .. it's Sid app..
If you are using PC, with chrome, follow the link, press f12 and this icon in the middle (Device Toggle Toolbar ):