Got an interesting situation. When I purchased my bronco, it had 33 in tires. The speedometer had been recalibrated, but when I check the calibration #, it was the stock #, and showed 6 changes remaining. This leads me to beleave that the owner changed the plastic gear at the end of the tranny, the way you would do it before the digital odometers were used(pre 92). Is this plastic gear still replaceable in the trucks with a cpu contolled odometer? What is the procedure of replacing the little gear? If I get this done, does anybody know what the cal # is for 35's?
Thanks a lot, Dave

93 Bronco
351, 4in, 3.55, 35 BFG muds

 

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As far as I know there is no gear to be replaced to calibrate the speedo on your truck. I could be wrong though.

 

The conversion constant for 35's is 8.09 I agree with the previous poster, I don't think there is a gear. If you have 6 changes on your PSOM left then it's never been changed from factory tire settings. I'm emailing you an article on how to change your conversion constant and how to calculate it for different tire sizes. Good luck, Ben

 

I checked my book and the PSOM (Programmable Speedometer and Odometer Module) gets it's reading from the rear axle sensor which is mounted on the top of your 8.8" rear. It monitors rear axle speed by sensing teeth on an exciter ring mounted on the ring gear. I think the only way for someone to have recalibrated your speedo without reprogramming it would have been to replace the rear axle ring gear, and then I'm not sure it would have done it properly. Good luck, Ben