What gear ratio do I have?

[stng]

So I bought a used 2000 Mustang GT, and if definately has aftermarket gears but I am not sure if they are 3:73's or 4:10's, the guy I bought it from didnt know either, as he was the second owner... All he knew was that the speedo was off by 10 percent. So here are some RPM's at speed with the 10 percent correction, which I am sure is pretty close to correct based on the radar speed checks on the freeway...

At 70 mph (Speedo says 77) I am taching between 2350 and 2400 RPMs at 80 mph (Speedo says 88) I am taching 3000 rpms.

Any one have any idea?

Thank You

 

[ponysarepretty]

A4 or 5spd?

Does anyone know the actual gear ratios for the A4 and the M5, mainly just the overdrives...

 

[stng]

5 speed manual

 

[DerekStangGT]

you have 4.10s. mine tachs 3k @ 80 as well, same tranny.

 

[Dope 97GT]

i got 4:10s and mine is about 7-9 mphs off at 60 and the rpms and speed sound about the same as mine.

 

[ponysarepretty]

3.59s if there is a 10% difference.. The stock are 3.27s right?

 

[hotmustang331]

Well with 3.73s in my dads 00 V6, speedo is 10-12MPH off. Its hard to say man lol. All you need to do is pace it with a friends car to make sure it 10MPH off. I would think 4.10s would be more than 8MPH off at 80. I drive my dads 00 at 75-80 indicated. its 2.5MHP per .10 gear upped. So every .20 is 5MPH. 3.73-3.27 = .46. That = 11.5MPH off.

4.10s-3.27 = .83 that= 20.75MPH off.
thats the theory anyways, and seems right to me. Looks like you got 3.73s to me

 

[cronin49]

373's are 13.15% steeper than 327's, your speedo would be off more than it is if you had 410's. I turn 70mph in 5th@2000rpm with my 373's. Try that out and see. its hard to tell without driving it.

 

[Pearl02]

You could do it the hard way. Jack up the car. Put a piece of tape or some other marking material on the right tire. Leave the car in neutral and turn the driveshaft. Count the number of turns the driveshafts makes for one revolution of the tire. If the driveshaft turns 3.73 times and tire makes one revolution, you have 3.73 gears. Pearl02.

 

[97gtblue]

i got 4.10's running about 3 grand at 80mph..and its about 9mph off

 

[tjm73]

At 70 mph (Speedo says 77) I am taching between 2350 and 2400 RPMs at 80 mph (Speedo says 88) I am taching 3000 rpms.

In which gear do you get these rpm's? 4th or 5th?

If that 3000 at 80 is in 5th (I'm positive it is) you have 4.10's.