I have a '97 Geo Tracker 2 wd with 5 spd manual transmission. Rear axle ratio is 5.12:1. I just exchanged rear axles and installed one with a 4.3:1 ratio. The speedometer now reads approximately 10 mph slow. What's available to correct it?
I think the speedometer gear is in the transfer case, but I don't know if it's as simple as changing it out with one from a 4.30:1 vehicle.
Glancing at the FSM, it looks like the speedometer drive gear is removable from the rear output shaft. I don't know which is necessary, the speedometer driven gear on the end of the speedometer cable or the speedometer drive gear on the main shaft. Sorry.
What kind of performance/driveability are you noticing with the lower gears? Do you like it?
I have been using my GPS and it works well. 45mph=55, 50=60; 55=67; 60=72. I can now cruise on the highway at 3000 rpm and be traveling at 68 mph. As for fuel economy, the first tank went from 30mpg to 36 mpg. Performance is good.
The Magellan GPS allows you to accumulate trip mileage as well as use it for a speedometer. It seems to be very accurate. First report was on 1/2 tank of gas. Going to run the entire tank out this time before calculating mileage. One hundred miles on the odometer translates to 121 on the GPS.
I think the Speed is calculated on segments by a sample distance between Point A and Point B divided by an internal clock time (lets say, .001 Sec to .005) and repeats all over again. I believe the GPS system has an Universal Clock that syncs all Satellites and GPS Receivers.
The distance travel is different since is based on a road map Vs an actual road reading (both could not be accurate adding a larger degree of inaccuracy) from Point A origination and Point B final destination.
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