7.3IDI speedometer gear

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08-12-2014, 10:38 PM

oldblue89

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7.3IDI speedometer gear

Hey, I am swapping axles on my 1989 F-250 from 4.10 to 3.55. It has a ZF 5 and BW 1356 transfer case. The tires are the stock 235 85 16. What speedometer gear do I need for the 3.55 gears?

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08-13-2014, 07:12 AM

tjc transport

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you will need to figure out how far off the speedometer is, then adjust the gear sizre by that. every 2.5 mph it is off at 55-60 mph equals one tooth on the cable gear.
if it is reading fast, add a tooth, if it is reading slow, take a tooth off.

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