I just bought a 1998 Mustang GT Convertible. Auto Trans. 125000 miles. The precious owner said the car had a chip install from a precious owner. He also said the speedometer reads high. I'm traveling down the road at what the speedometer say's at 80MPH @2900 RPM's. This is on a 65 MPH highway. People are passing me up like I'm standing still. I coming to the realization the rear end gears have be changed. I know the trans is going through all the gears. What is the factory gear ratio for this car? Any help would be greatful. Thanks Jerry

 

2.73's!

 

Do you have a GPS App on your phone, or a GPS?

I haven't used in dash speedos in any of my cars for years. I rely on a GPS reading.

 

Yes I have a GPS app on my phone. I'll give it a try. My main issue is not the speedo, but the high rev's. I'll have to jack it up and check the rear end ratio. 2.73? Holy cow. I'm sure I don't have that in the rear end. Thanks Jerry

 

I jacked up the care yesterday to check the gear ratio. With 1 full turn of the wheel, the driveshaft turned 4+ times. So I'm guessing a 4.11 or so. Something else happened tonight. I was backing into the garage. Put it in park, then the RPM's revved up big time. What is up with the car? Help.