Trying to figure out gearing...

Jrichker -

Jack the rear of the car up on jackstands and place the transmission in neutral. Make a paint mark on the rear part of the driveshaft that is visible from the side of the car. Make a mark on the tire, and rotate it one turn while counting the number of turns the driveshaft makes.

less than 3 turns of the driveshaft = 2.73:1
about 3 turns and a little more = 3.08:1
a little more than 3 1/2 turns = 3.55:1
almost 3 3/4 turns of the driveshaft = 3.73:1
a little more than 4 turns of the driveshaft = 4.10:1

See http://www.geocities.com/mgnedell/no...ch/speedo.html for information on speedo drive gears.

see http://www.corral.net/tech/gearcalc.html for a calculator that uses RPM, rear end ratio and tire size to calculate speed

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TRWXXA -
The best way is to mark the driveshaft, turn the rear wheels 10 times, count the number times the driveshaft rotates, then divide that number by 10.

When you turn the wheels only once, it's hard to tell the difference between 3.08 turns of the driveshaft and 3.27 turns (or 3.55 turns and 3.73 turns, etc.). I know this for a fact. I thought I was getting a 3.08 rear end and really wound up with a 3.27 (even better). Only after I took off the differential cover and counted the pionion and ring gera teeth did I discover the error.

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