88FJ62 SPEEDOMETER GEAR RATIO ADAPTER (1 Viewer)

[88Retired62]

Has anyone found a source that can supply a Speedometer Gear Ratio Adapter that can compensate for the reduced driveline rotation ( speedometer indicates a slower speed) when installing taller tires. Specifically stock 28” to 33” diameter. Is there an industry formula, knowing the current tire sizes and differential gearing into a workable Gear ratio adapter?

 

[Dixon Santana]

Just solved this issue on my 60 about a month ago. Commercial Speedometer in California is the place to go, it's not cheap (mine was $90) but it works. Here are some pictures on how it goes together.
Hope this helps.

 

[antichrist]

Yeah I Went to Commercail Speedo too (West Sacramento) after my Diesel/Gears/tires changes. You need to download a GPS speedometer app for your phone spend some time at various speeds and determine the ratio between indicated speed and what the GPS speed shows. Commercial Speedo will need to know your ratio so they can cusomize the adapter. Mine was $90 too but it was the bees knees once done