First off hello to all, as you know i am the new guy around here and will only be ar ound for a short time as ai have to go over to the moutains and the sand for a while...

Down to business i am running 39.5 truxus sts geared at 5.71 the speedo is on the money. However, does this mean that the odometer is or do i need to do the whole 39. 5/ 29= 1.36 and multiply that by my odometer!?

i really appreciate the help j ust makes a huge difference in mileage when you are figuring it difference between 12 and 16.. and we all know what im hopin for at $4 + a gallon.

 

maybe I'm misunderstanding but if the speedo is right on, the odometer will be too.

 

Speedometer and odometer can be off from each other. Why? At least in the pre-computer vehicles, the odometer is all gear driven so it is the most accurate. The speedometer uses a spinning magnet and calibrated spring to give an indication of speed. It can read fast or slow depending on how well calibrated it was originally and how that calibration has changed over the years. When I ordered a speedo/odo calibration box for my '85 when I ran 33s and 5.29 gears, the calibration tests I did revealed a 10% odometer error and a 13% speedometer error. I think factory specs are to have the speedometer read withing 5% of the actual speed with the stock tires and gearing.

The way the shop had me check the odometer readings/error was to drive a measured 10 mile section of freeway (using the mile/paddle markers beside the road) and record the starting and ending odometer readings, including an estimate of the fraction of a 10th mile on the odometer dial. This can give you an odometer error reading of better than 10%.