Snowmobile Gear Ratio Calculator
Determine your snowmobile’s final gear ratio. This helps in understanding how changes to sprockets affect acceleration and top speed. Enter your current or planned sprocket teeth counts below.
Understanding Snowmobile Gear Ratios
A snowmobile’s gear ratio is crucial for its performance. It determines the relationship between engine RPM and track speed. Modifying gear ratios allows riders to fine-tune their sled for specific conditions or riding styles:
- Lower Numerical Ratio (e.g., 2.00:1): Generally means higher top speed but slower acceleration. Often preferred for lake racing or long, open trails.
- Higher Numerical Ratio (e.g., 2.50:1): Generally means quicker acceleration and better low-end torque but lower top speed. Ideal for deep snow, boondocking, or technical trails.
The overall gear ratio is calculated as follows:
Overall Ratio = (Bottom Gear / Top Gear) × (Track Driveshaft Sprocket / Drive Clutch Sprocket)
If your snowmobile has a direct drive system (chaincase output directly drives the track driveshaft without a jackshaft and secondary chain/belt), the “Drive Clutch Sprocket” and “Track Driveshaft Sprocket” effectively have a 1:1 ratio relative to each other for this calculation. In such cases, inputting ‘1’ for both these values will give you the chaincase ratio, which is your final drive ratio.
How to Use This Calculator:
- Locate the sprockets on your snowmobile:
- Top & Bottom Gears: These are inside your chaincase. The top gear is usually smaller and connected to the driveshaft coming from the secondary clutch. The bottom gear is larger and drives the jackshaft or track driveshaft.
- Drive Clutch Sprocket: If your sled has a jackshaft system, this is the sprocket on the input side of the jackshaft (driven by a belt/chain from the chaincase output).
- Track Driveshaft Sprocket: These are the sprockets on the track driveshaft itself, which engage the track. If you have a jackshaft, this is the output sprocket on the jackshaft.
- Count the number of teeth on each sprocket.
- Enter these values into the respective fields in the calculator.
- Click “Calculate Ratio” to see your overall gear ratio.
This calculator helps you understand the impact of sprocket changes before you make them. Always consult your snowmobile’s service manual or a trusted mechanic if you’re unsure about making modifications.