How do I know what size 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 count speedometer drive on gear teeth?

Look at the gear from the side.

1. Mark the tooth where you start.
2. Count the peaks all the way around the gear. In the picture below, each red dot is 1 tooth.

How do you calibrate a GM speedometer?

Electronic Speedometer

1. Determine the distance of the test drive needed to recalibrate your speedometer.
2. Press and hold the calibration button on the speedometer, start the vehicle and release the button.
3. Press the button again and drive the distance prescribed by the speedometer manufacturer.

How do I calibrate my speedometer?

Press and hold the calibration button located on the speedometer, start the vehicle, and then release the button. Press that button again and then take the test drive. Once you have driven the distance needed, press the button once more and the speedometer will calibrate itself to accommodate the new tire size.

How can I speed up my speedometer?

Changing the ratio between the drive gear and the driven gear will change the speedometer reading. A driven gear with fewer teeth will speed up the speedometer reading; more teeth will slow down the reading.

Which gear is the drive gear?

Spur gears are gears in the same plane that move opposite of each other because they are meshed together. Gear ‘A’ is called the ‘driver’ because this is turned by a motor. As gear ‘A’ turns it meshes with gear ‘B’ and it begins to turn as well. Gear ‘B’ is called the ‘driven’ gear.

Can you recalibrate a speedometer?

Electronic speedometers are easy to calibrate. Manufacturers always provide the distance of the test drive needed for speedometer calibration. This information is normally available in the owner’s manual. Identify the speedometer calibration button and press-hold, crank your vehicle and then release the button.

Does a 700R4 have a speed sensor?

Most GM transmissions such as TH350, TH400, 700R4, TH200, H250’s may use the AutoMeter # 5291 speed sensor. For these models use a model # 5292 AutoMeter speed sensor.

What are the gears on a TH400 speedometer?

700R4 / TH400 Speedometer driven gears, comes in 34 to 45 tooth. (Also fits 208 transfer case). Speedometer Calibration Variables such as the vehicle’s axle ratio and tire diameter affect the accuracy of the speedometer.

How to calculate the gear on a speedometer?

Speedometer Gear Calculator. 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.

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.

What are the teeth in a speedometer transmission?

Calculated speedometer driven gear tooth count is: teeth. Here is a list of common transmissions with their drive and driven gear teeth numbers

https://www.youtube.com/watch?v=BpEO1sHLp7Q