Changed gear ratio but never recaliberated, wrong mileage?
- Thread starter derek02gt
- Start date
blumi00GT
Founding Member
Haha, no - sorry guys. The odo uses the same speed pickup on the tranny as the speedo. So your odo ticks the same amount faster like your speedo does.
To be exactly, 14.1% faster when you changed form 3.27 to 3.73.
Blumi
To be exactly, 14.1% faster when you changed form 3.27 to 3.73.
Blumi
03redfiregt
New Member
yep your odometer is not reading the right miles. If you hjave been driving around for a year like that its probably showing a good amount more miles than you actually have.
Give Me TP
Member
The milege would have been high by an even greater amount if you had been running 4.10s. If you have a flash tuner or SpeedCal, you could approximately correct the odometer for all this time you have been running with an uncorrected speedodometer, if you know when the 3.73s were installed.
Z28 KILR
Founding Member
With these tuners what would prevent somone saying that they have 4.10s but really don't. Would your mileage be less than what is actually on the car?
Give Me TP
Member
Nothing prevents someone from saying they have 4.10s whether or not they have a tuner. One guaranteed way to verify the gear ratio is to jack up a rear wheel and count driveshaft revolutions per one complete turn of the rear wheelZ28 KILR said:
If someone with a tuner loaded the setting for 4.10s but actually had stock gears, the true mileage on the car would actually be greater than that shown on the odometer. In the case of a 99-04 GT with stock 3.27s, setting the speedometer correction to 4.10s with a tuner would for instance would only show 1000 miles on the odometer for every 1,253.8 miles actually driven.Z28 KILR said:
thanks for the replies people. I do know the exact date i got them installed and the exact mileage as I had a ford dealer put them in for me. I also have 18inch tires in 275/35/18 around the whole car..that wouldnt do anything would it? this is so depressing as I ruined the resale value bigtime..I just want to know how bad I screwed it up.
Give Me TP
Member
Since you know the mileage at the time the gears were installed, you can get the ododmeter back to the correct mileage if you have a tuner. The tire change also affected the odometer but actually has offset the effect of the 3.73s somewhat
durknutz01GT
New Member
my car's previous owner had gears installed. don't think he ever had it tuned... i've been driving it since summer of '03. don't want to think about how off my mileage is. i bought it with 14K, i now have 49.2K. i didn't think i drove it that much. now i know i probably didnt....
04GT
New Member
Anybody wanna buy a speed cal? $40...only used for 6 mos.
I was gonna put in the FOR SALE section.
I was gonna put in the FOR SALE section.
wms004
Founding Member
03redfiregt
New Member
Give Me TP said:
I did'nt know you could turn back the odometer with a tuner. your sure? I dont think thats possible. BUt in any case the tire size he has on the car would not effect the odometer because it is the same aspect ratio as the stock tire and wheel size.
Give Me TP
Member
03redfiregt said:
One complete rotation of an 18" diameter tire goes a longer linear distance than a 17" diamter tire. Since odometer readings are essentially based on transmission tail shaft revolutions a car with an 18" tire is going to travel further for a given number of tail shaft revolutions, thereby causing the odometer to understate (slightly) the actual mileage.
You are not "turning back" the odometer with a tuner. That is not possible and would be also be illegal. You can "correct" the odometer by temporarily recalibrating the speedometer to (in this case) 4.10s or 4.30s for the required mileage to get it back to or close to the actual mileage. Then the speedometer could be recalibrated to 3.73s from then on. A tuner can also correct for tire diamter changes, others here on the boards have done so.
jstreet0204
Active Member
Give Me TP said:
All the guys with tuners, and 500 miles left on their warranty are now programming their cars with 8.50 gears....
Give Me TP
Member
i too have been driving my stang aorund for a whole month with the 4.10s and the speedo uncalibrated. i want to fix it as well as the milage. now im reading here about tuners and whatnot but my question is can i do the same with a chip? they have similar descriptions and are a lot cheaper. can i recalibrate the speedo and clear off the code my midpipe throws?
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