SPEEDO CALIBRATION

[mrvids]

I bought a '97 4.6 used, and the previous owner went from a stock gear ratio (I can't find it off hand) to a 4:10 rear end. Changed the speedo gear in the trans from 25 tooth to 23 tooth and the speedo still is off 10%. Tire size stayed the same. What is the next step? Locally there is one and only one shop in town that can work on it and they want $200 to $400 to recalibrate it, but they won't give me a firm quote until after they work on it.

 

[RandyStinchcomb]

1st ther is NO 25 tooth speedo gear that Im aware of, Ford goes as high as 21 tooth
2nd, the 23 tooth gear is NOT designed to work wth the drive gear in a Gt's T-45 trans, you can get close but not spot-on by changing the drive gear on the output shaft of the trans to the Cobra gear and a 21 or the "aftermarket 23 tooth" driven gear on the VSS.
this does require you to remove the ext housing off the trans, big job.

price on parts to-do this is @$50.00

 

[mrvids]

The car is an automatic, and you're right, after checking again I discovered the gear removed was a 23, not 25 tooth. And it was replaced with a new 23 tooth.
Which explains why the speedo is still messed up....
Which is also why I turn to folks like you who actually know what they're talking about.

 

[Kilgore Trout]

Which is also why I turn to folks like you who actually know what they're talking about.

Heh, must be your lucky day you got your answer from one of the board's best

 

[RandyStinchcomb]

hmmm, well being an automatic your going to have to get the speedcal then as what I posted up was for a manual trans

KT > thanks bro'

 

[superstang01]

what gear would i need to correct my speedo after an 3.73 gear set swap on an 01 gt 5 speed?

 

[RandyStinchcomb]

what gear would i need to correct my speedo after an 3.73 gear set swap on an 01 gt 5 speed?

1999 up Mustang speedo's are electronic, so you'll need someone wth a tuner or the speed-cal