My car is supposed to have a Terminator IRS with 3.55 gears instead of the '01 3.27, so I expected my speedometer to be off. The difference between 3.27 and 3.55 is only 8.563%, so I'm thinking "80mph" on my speedometer would actually be 73.7mph. Most of my driving is 10 miles each way 45-55 on local roads so i really didn't think it was a big deal. I will say that 1st gear always seemed a little short but the pull in 2nd was nice.
I had a chance to test the speedometer last week, and my "80mph" is actually "71mph" as measured by the digital speedometer on a brand new CTS. That's a 12.676% difference, and a lot closer to a 3.72 gear ratio over 3.27 (+13.67%).
Does this sound like 3.72 gears to you guys? Does this mean my mileage is increasing 12.67% faster than actual, too, and depreciating the car? Does anyone know if the "3.27", "3.55", and "3.72" ratios are accurate, or if "3.27" is really 3.2675? It bothers me that the 3.72/3.27 ratio does not match 80/71mph closer.
Can the dealer reset the gear ratio on the computer? or do i need a handheld tuner to do that, or a Speed Calibrator card installed?
thanks -
pix -
I had a chance to test the speedometer last week, and my "80mph" is actually "71mph" as measured by the digital speedometer on a brand new CTS. That's a 12.676% difference, and a lot closer to a 3.72 gear ratio over 3.27 (+13.67%).
Does this sound like 3.72 gears to you guys? Does this mean my mileage is increasing 12.67% faster than actual, too, and depreciating the car? Does anyone know if the "3.27", "3.55", and "3.72" ratios are accurate, or if "3.27" is really 3.2675? It bothers me that the 3.72/3.27 ratio does not match 80/71mph closer.
Can the dealer reset the gear ratio on the computer? or do i need a handheld tuner to do that, or a Speed Calibrator card installed?
thanks -
pix -