I just realized this. No wonder it is 100 miles to her house instead of 90. No wonder people are whizzing by me on both sides and I am getting no speeding tickets!
Now how am I supposed to fix this? On my older Fords, it would have been a little color-coded nylon gear at the end of the speedometer cable into the transmission. I don't have a shop manual handy at the moment. Any ideas/suggestions? This car has had three owners and was apparently well cared for for 52K miles. The only strange thing is that it has a Mach 1 bumper and grille. Maybe there are other strange things--like somebody changed the axle ratio to a 3.55 without changing the speedo gear. That would explain why it feels FASTER than my 2002 stock GT did. But would that turn the speedo faster or slower?

 

You most probably have 3.73s if its 10%

you need to buy a tuner or speedcal to correct your speedo.. but first you need to jack your car up, the rotate a rear tire 1 full rotation and count how many rotations the driveshaft spins. That number will tell you your gear ratio.

 

Well. After two visits to the Ford dealer who sold me the car, I have a little more knowledge. At the first visit, after a road test with me to verify the problem, the technician could not get the PCM to accept new information. At the second visit, it was determined that I have 3.73s rather than the stock 3.27 gears. The burning question for me, which they haven't totally answered yet, is will they eat the cost of the work? They sold me the car with a speedometer that is way off, showing a higher mileage than the car has actually gone, so I believe they should fix it for free.
Anyway, the service manager told me that they were going to obtain a flash device with which to reprogram the PCM. So one more visit. I can hardly wait! Meanwhile, every time I drive the car, I am adding nonexistent miles, and have to calculate my speed based on the error. I still have to wait also to calculate fuel economy accurately. Anyway, I doubt I'll ever see 27 mpg again, as I did with my stock 2002 GT. Darn! I KNEW this car was faster than my old one when I got it--I thought it was just a stronger engine. Maybe 5.5 sec to 60?
And HOSS302, your judgment on the 3.73s was right on the money. Thanx.

 

get a sct or diablo

 

Quit bitching you got gears

 

What, me complain? No. But the Ford dealer had better eat the cost. As to what gears I would choose? It's never that simple. My Dad and I ordered a new 1969 Mach 1 Super Cobra Jet, Acapulco Blue, 9T02R150823, with the 3.91 Detroit Locker axle in March 1969. Years later, sifting through the data that people have verified over time, I came to find that what was delivered was a set of 4.33s. That explained the lack of top end, and the car's unsuitability as my Dad's commuter--although weekends on the avenue were a lot of fun for me! For the two midyear Sting Rays I had, I thought 3.70s were ideal, a great compromise, especially with the close ratio 4-speed. So yeah, I do like the 3.73s, and 5th gear makes the whole deal easier than in the old days.
I test drove a couple of 2003 Mach 1s, and with one of them, made a max performance takeoff (the salesman didn't mind). So I liked the 3.55s and the extra 45 hp, though we couldn't get together on price.
Come to think of it, the very first GT (5T09K155426, Poppy Red 2 plus 2) that we got new, had a 3.50 open diff, which at the time I thought was rather tall gearing, especially with the 289's power band being way up there in revs. Took my driver's test on that puppy...

 

Well! That took a while, but the Ford dealer finally got the right tool to reprogram the PCM, and while I was in there yesterday getting the work truck repaired, they agreed to eat the cost of correcting the speedometer. So I have an appointment for Monday morning...I can't really enjoy my 3.73s until the speedo/odo are corrected, so I guess I am happy in advance.

 

glad you got it all sorted out...now begins the search for other parts on the car that you didnt know about haha.

 

Is there a Supercharger under the hood you didnt notice?

 

The only other thing was one of those wretched GPS things for in case your ride is stolen. (Subscription item, dealer installed for extra profits.) I ripped that out by the tonsils--the flashing blue LED was driving me nuts.
Anyway, the rather sluggish Ford dealer finally had their best tech reprogram the PCM to recognize the gears it is pushing, and that part is fantastic. Perfectly accurate speedo, and hole shots against those pesky Hondas are no problem! But the strange thing is that as soon as I got it back, it was pinging--preignition. I have to talk to that tech and ask what else he did in there. Maybe he assumed that such a hot rod should be set up for premium fuel? Next, I will try a tank of the good stuff, and maybe not even talk to the tech. The less someone else touches my baby, the better.