I have installed the 4.30 gears (and love them). My problem is my speedometer is off by 6mph at 50mph (about 12%). I have already installed the highest gear (21tooth) available from Ford. On my year truck the speedo is electronic but mechanically calibrated (1997 and 98). Does anyone know how to correct this?? I know there are a lot of people who have put 4.56 rears in their pre 99 F150's and Mustangs, how do they correct the speedo?
I await the experts.....

 

try http://www.baumannengineering.com/misc.htm - they have a 23 tooth that might do the trick.

Ian

 

WLF,
After changing my gear to get it as close as possible I used an "Electronic Ratio Adapter" from Abbott enterprises. There number is: 800-643-5973 cost was about $175 big ones.

 

I installed the 23 tooth and mine is now right on. Thanks, the electric correctors were my next step..