FORD AOD x 2,80 x 3,25 x speedometer!

[Alexei]

Dear fellows,

My 72 has a 351C with a Ford AOD. Since the final relation is too low, I decided to install a new 3,25 ratio. Since now it’s a 2,80 ratio, Will I have to change something else to keep my speedometer accurate?
Thanks!

 

[Sheriff41]

Replace the speedometer driven gear on the transmission end of your speedo cable with a 19-tooth gear.

 

[Alexei]

Thank you! And where do I buy this?

 

[Sheriff41]

Here's one: https://lmr.com/item/LRS-17271E-K/83-95-Mustang-19-Tooth-Speedo-Gear-Kit-Auto

Another: https://www.cjponyparts.com/speedom...matic-manual-transmission-1965-1998/p/HW1276/

You can also search for "Ford AOD 19-tooth" to find other vendors

 

[Alexei]

Thanks a lot!

 

[Superbond]

Each tooth is 5mph. So if your out by 15 get a gear with 3 extra teeth and so on

 

[SVGAL42]

Each tooth is 5mph. So if your out by 15 get a gear with 3 extra teeth and so on

I have a question re: speedo gears~ If my speedometer is reading 5 miles slower than actual speed do I replace gear with a gear that has fewer teeth or more?

 

[Don C]

Less, 1 tooth should do it.

 

[SVGAL42]

Less, 1 tooth should do it.

Thank you!

 

[mrgmhale]

We got so lucky with the AOD we transplanted into our 73 Mach 1. I had installed a Dakota VHX analog gauge instrument panel two years prior to the AOD swap being done. Once done I was able to electronically set the calibration for our speedo without having to deal with getting the right gear. To calibrate it I simply found a stretch of road with mile markers every 1/10th mile. selected when to begin the test run, drove from one marker to the other, then selected the option saying the test run was complete. Done! I had already been very happy with the Dakota panel, in both our 73 Mustangs. But, that really made my day. I tested it against a GPS speedometer app and found the Dakota calibration was dead on at all speeds I checked for (25, 35, 55, 65, and "a little bit faster even").