N0DIH
April 29th, 2007, 04:14 PM
Anyone here by chance know how to calculate the speedo values for my 94 Fleetwood? I just swapped axles from 3.42's to 3.08's (temporarily).
TunerCat OBD1 is notorious for calculating these values incorrectly.
Can anyone help?
This is a sample:
235 70 15's with 3.42's.
GM (factory values):
Scaler: 25
Fraction: 1.016
Scantool: 42
Time between pulses: 35.416
Pulses per driveshaft rev: 40
TunerCat calcs
Scaler: 25
Fraction: 0.981
Scantool: 42.465
Time between pulses: 35.323
Pulses per driveshaft rev: 40
So from these values (the GM factory ones), I have changed to 3.08's with the same size tires. Can anyone here help? And can someone explain what these values all mean in the speedo calibration?
Thanks!
TunerCat OBD1 is notorious for calculating these values incorrectly.
Can anyone help?
This is a sample:
235 70 15's with 3.42's.
GM (factory values):
Scaler: 25
Fraction: 1.016
Scantool: 42
Time between pulses: 35.416
Pulses per driveshaft rev: 40
TunerCat calcs
Scaler: 25
Fraction: 0.981
Scantool: 42.465
Time between pulses: 35.323
Pulses per driveshaft rev: 40
So from these values (the GM factory ones), I have changed to 3.08's with the same size tires. Can anyone here help? And can someone explain what these values all mean in the speedo calibration?
Thanks!