Gear Ratio Calculator

This is a condensed version geared towards the Sammy which makes it easier to use for the Sammy. The original one is from http://www.grimmjeeper.com/gears.html if you want more gearing options. THX Grimm for putting this together.

There are two copies of the form so that you can do a side-by-side comparison of two combinations.

Step 1: Select transmission from the drop down list or, if it's not in the list and you know the gear ratios of your transmission, enter them below.

Number of forward gears
1st Gear
2nd Gear
3rd Gear
4th Gear
5th Gear
6th Gear
Reverse
Manual or Auto with lockup torque converter
Automatic without lockup toque converter

Step 2: Select transfer case from the drop down list or, if it's not in the list and you know the gear ratios of your transfer case, enter them below.

High Range
Low Range
STaK 3rd Range

Step 3: Select underdrive.

High Range
Low Range

Step 4: Select axle gear ratio.
Ratio

Step 5: Select tire size.

Inch
Metric /R

Step 6: Hit the calculate button and read the results below.

If you want to clear the results and try again, hit this button

The following chart lists the final drive ratio of all combined gears (transmission, transfer case, underdrive, axle) in all possible combinations

Final Drive Ratio
Gear	Underdrive High Range			Underdrive Low Range
Gear	Transfer Case High Range	Transfer Case Low Range	Transfer Case STaK Range	Transfer Case High Range	Transfer Case Low Range	Transfer Case STaK Range
1
2
3
4
5
6
R

The following chart lists the crawl speed you will be going while the engine is at a given RPM. Crawl speed is calculated based on the lowest low range (transfer case and underdrive in low range) available in your rig.

Crawl Speed at Given RPM in Feet Per Minute
Gear	RPM	RPM	RPM
1
2
3
4
5
6
R

The following chart lists the road speed you will be going while the engine is at a given RPM. Road speed is calculated based on the transfer case and underdrive being in high range.

Road Speed at Given RPM in Miles Per Hour
Gear	RPM	RPM	RPM
1
2
3
4
5
6
R

The following chart lists the RPMs your engine will be turning while driving at a given speed on the road.

Road RPMs at Given Speed
Gear	MPH	MPH	MPH
1
2
3
4
5
6
R