How do I know what speedometer gear I need?

To determine your tires true diameter in relation to determining what speedometer gears you need, measure from the ground up to the center of the axle then multiply by two. The actual run out of the tire can be as much as 2 to 3 inches less than what the circumference of the tire measures.

How do you calculate Speedo ratio?

What gears should I get?

1. Count the teeth on the speedometer drive gear.
2. Find the gear ratio for the drive axle.
3. Calculate tire revolutions per mile.
4. Calculate the required tooth count for the driven gear.
5. Get the Driven Gear (for your transmission) with the closest tooth count to your calculations.

What kind of speedometer does a 700R4 use?

Your speedometer may or may not show a number. Most speedometer from 1965 on use 1000. Twelve speedometer driven gears are available for the 700R4 / 4L60 transmissions to calibrate the speedometer with various axle ratios and tire diameters.

How many gears are in a 700R4 transmission?

The following speedometer drive gears and driven gears are available for the 700R4 / 4L60 transmissions. Most cars and trucks with low rear end ratios will take a 15 tooth drive gear. There are two driven gear housings, one for 34 through 39 tooth driven gears and one for 40 through 45 tooth driven gears.

How many gears are in a Dodge speedometer?

Most cars and trucks with low rear end ratios will take a 15 tooth drive gear. There are two driven gear housings, one for 34 through 39 tooth driven gears and one for 40 through 45 tooth driven gears. Look at the bottom of the speedometer face for the numbers 940, 960, 1000, or 1020.

How do you calculate rear end ratio on a speedometer?

To determine your rear end ratio, raise both tires off of the ground, turn both tires at the same time one complete turn, at the same time count the turns of the drive shaft, this is your ratio. Speedometer Calibration: Variables such as the vehicle’s axle ratio and tire diameter affect the accuracy of the speedometer.