gear axle ratio question
Hi all, We got our Excursion back from the dealer with a new fuel pump. We have been talking about changing out the gears for better towing. Right now we have a V10 with a towing package and a 3....
Forum Discussion
WE3ZS wrote:Yak wrote:
Remember to change the parameters in the PCM when you're done.
Changing the final drive ratio does not require any adjustments to the PCM parameters. The speed is read off of the tone ring on the ring gear, so it is actually reading the tire revs and uses the revs per mile to calculate the speedometer/odometer readings. Changing tire size (diameter/height) would need the revs per mile to be adjusted in the PCM to have the speedo read correctly. I have changed both gears (3.73 to 4.88) and tires (31.6' to 32" to 35.28") and verified speed with GPS, gears didn't affect speedo but tires did.
They also have a sensor on the output shaft. It's been a while but I'm thinking there are resetable parameters gearing and tire size
