Speedometer requires how many revolutions per mile?

[BigSix]

Since swapping in a Dana 300 tcase I have hooked the speedo cable back up but the speedometer is showing faster than I am actually driving. I would like to correctly calculate which gear to get for my tcase but it requires knowing how many revolutions per mile our speedometers require. The Jeep this transfercase came from required 1000 revolutions of input per mile.

[jtrichard]

Every US speedometer that I've come across is calibrated for 1000 turns per mile. (That's turns of the speedometer cable).

[TopFuel1966]

This link is for GM automatics but it contains a chart and a math formula that you may find useful:

http://www.transmissioncenter.net/sp...n_______va.htm

[BigSix]

Originally Posted by jtrichard

Every US speedometer that I've come across is calibrated for 1000 turns per mile. (That's turns of the speedometer cable).

Thanks. Safe to assume my GMC is 1000?

[jtrichard]

I would think so