I just got my 4.10s in and i think my speedo runs about 10 mph fast....how do i go about fixing this? will it be electronic with my truck? Where would i go to get this done? How much will it cost? thanks!

for a '92, it's just gear driven...i dunno where it is located exactly, but there's a small gear (about 1" dia.) that's on the side of the tranny that you have to remove...it only requires a socket wrench to remove it and a hayne's manual to find it :D

you can do it yourself, easily...all you need to do is locate it, pull it out, count the teeth, and go get a new one from Ford...there's a formula to use to find out how many teeth you need on the new one, but i can't find it right now...maybe someone else will be kind enough to post it :)

found it!!

newGear/newRingAndPinion = oldGear/oldRingAndPinion

so all ya gotta do now is take out the old speedo gear and count the teeth :)

hope this helps!

Follow the speedometer cable to the rear of the transmission. It's attached to the gear holder. Remove the holder, usually one bolt and a clamp, and pull the unit out. For the new size, divide the gear ratio you had by what you have now. Count the number of teeth on the gear, and multiply that by the result.

For instance,

3.55/4.10=.87
Teeth on gear = 19

.87 x 19 = 16.53, so you would need a 17 tooth gear to correct the speedo.

I think this is right, if it's wrong, reverse the numbers in the first equation.

I was told that you can figure each tooth to be 3 MPH at 60. real 60, not what you are reading. but I don't know if that is true.

ex90

thanks for all the help guys!