The TH350 speedometer gear calculator is an essential tool designed to help vehicle owners and mechanics calculate the correct speedometer gear for vehicles with the TH350 transmission. Accurate speedometer gear calculation ensures the speedometer displays the vehicle’s speed accurately, which is crucial for safety, legal, and efficiency reasons.
This calculator takes into account various factors that influence the vehicle’s speed reading, such as the transmission’s drive gear teeth, the axle ratio, and the tire revolutions per mile. By inputting these values, the calculator provides the necessary number of teeth for the driven gear, ensuring the speedometer reads accurately regardless of modifications to the vehicle’s tires, differential, or transmission.
Formula of TH350 Speedometer Gear Calculator
Drive Teeth X Axle Ratio X Tire Revolutions per Mile = Driven Teeth / 1001
Here’s a detailed breakdown of the variables:
- Drive Teeth: The number of teeth on the gear attached to your transmission output shaft. This number can be found by manually counting the teeth.
- Axle Ratio: This number represents the gear ratio between your engine and your wheels. It’s available in your car’s manual or through an online search for your specific vehicle model.
- Tire Revolutions per Mile: Indicates how many times your tires complete a full rotation over the distance of one mile. This can be calculated with the formula:
Tire Revolutions per Mile = 20168 / Tire Diameter (inches). - Driven Teeth: The calculated number of teeth needed on the speedometer gear for accurate speed readings. This is the result you’re aiming to find with the calculator.
Table for General Terms and Useful Calculations
| Drive Teeth | Axle Ratio | Tire Diameter (inches) | Tire Revolutions per Mile (Calculated) | Driven Teeth (Estimated) |
|---|---|---|---|---|
| 15 | 3.55 | 26 | 798 | 18 |
| 17 | 3.73 | 28 | 754 | 20 |
| 19 | 4.11 | 30 | 714 | 22 |
| 20 | 2.73 | 32 | 677 | 16 |
| 22 | 3.08 | 34 | 644 | 18 |
Example of TH350 Speedometer Gear Calculator
To illustrate, let’s assume a vehicle with 15 drive teeth, an axle ratio of 3.73, and tire diameter leading to 800 tire revolutions per mile. Using our formula:
15 (Drive Teeth) X 3.73 (Axle Ratio) X 800 (Tire Revolutions per Mile) = Driven Teeth / 1001
This calculation would yield the precise number of teeth needed on the driven gear for accurate speedometer readings, demonstrating the calculator’s practical application.
Most Common FAQs
Changing your tire size affects the tire revolutions per mile, which in turn, influences the speedometer reading. Use the calculator with your new tire size to determine the needed driven gear teeth.
The calculator provides an accurate estimation of the required driven gear teeth number, assuming correct input values. For best results, ensure all inputs are precise.
This calculator is specifically design for the TH350 transmission. Other transmissions might require different calculations due to variations in design and function.