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Thursday, March 31, 2011

Mustang Rear Axle Gear Guesstimator

This is a thingy I put together a while back, a Rear Axle Ratio Guesstimator.

To use it just get going 40 to 50 mph in 4th gear (3rd for autos) and make note of the selected speed and rpm at that speed; then plug the numbers into the calculator. If you have non-stock rear tires that are of a different outside diameter than stock enter the tire size too.

Here's an example using my GT with 3.73 gears; 50 in 4th is just a bit over 2500 rpm:

It uses a fuzzy math algorithm, meaning that the input values for speed and rpm do not have to be dead on. It has proven to be pretty accurate...

Posted by CliffyK at 1:04 PM
Edited on: Thursday, March 31, 2011 1:14 PM
Categories: Mustangs