FST Gear Ratio Info

Formula First Technical Information Gear Ratio Checking Procedure

This is one method to check the gear ratios in your transmission to confirm that you have the correct Third Gear for Formula First. This procedure is done with the crank pulley marked at 300 and 216.

1. Raise one rear wheel off the ground to allow free rotation.

2. Mark the tire to verify each full revolution of the wheel/tire.

3. If needed, mount a degree wheel to the crankshaft pulley.

4. Make sure that the degree wheel is visually clear to record data.

5. Select 4th gear and rotate lifted wheel to bring the crankshaft degree wheel to TDC.

6. Rotate the raised wheel one full turn, observe and record the number of full degree wheel rotations and the degrees past TDC.

7. Select 3rd gear and rotate lifted wheel to bring the crankshaft degree wheel to TDC.

8. Rotate the raised wheel one full turn, observe and record the number of full degree wheel rotations and the degrees past TDC.

9. Using the chart below, verify the correct number of turns and degrees listed for the 3rd and 4th gear. This will also verify the correct final drive gears as well.

 

Gear
Teeth
O/A Ratio
Trans Ratio
Final Drive Ratio
Crank Pulley Turns plus Degrees
4th
27:24
3.67:1

0.89

4.125
1 + 300
3rd
23:29
5.20:1
1.26
4.125
2 + 216