Home

 

Social Media

 

Maps & GPS

 

Technical and Mechanical Index

 

Vendor Index

 

Calendar

THUNDER BEAR 4WD Technical and Mechanical Index
Technical and Mechanical
 

Tech Tips

Return to Top

Axle Gear Ratio & Tire size change conversion equation.

There are two equations for figuring this out.

Equation or Method #1

 

New Tire Size (in inches) / Old Tire Size (in inches) * Old Gear Ratio = New approximate ratio

 

35" / 33" = 1.0606 * 3.73 = 3.9560

 

37" / 33" = 1.1212 * 3.73 = 4.1821

 

Equation or Method #2

 

New Tire Size (in inches) * Old Ratio / Old Tire Size (in inches) = New Ratio

 

35" * 3.73 = 130.55 / 33" = 3.9560

 

37" * 3.73 = 138.01  / 33" = 4.1821

 

Both methods produce the same result. If you are going to use one, try and stick with it for your own personal consistency.

 

Refer to axle gear choices and select closest ratio to make the vehicle perform as close as possible to factory performance.

 

It is always considered acceptable to go to deeper gears (numerically higher) to gain more torque for crawling.

 

For the above factors, going from 33's to 37's on a 2021 Jeep Wrangler with Dana 44 AdvanTEK axles, the closest gear choice would be 4.10. However, choosing 4.56 would be better to give better gearing for future tire sizes up to 39" of 40"

 

 

Backlash 0.005 - 0.008

Pinion rolling torque 15 - 30 inch pounds

 

Carrier Split on Dana 30, 35, 44 is between 3.55 and 3.73

Meaning 3.73 and lower gears will fit the same carrier. 3.55 or higher gears will fit the same carrier.
This is important to know if you are going from a 3.55 to a 4.10, you'll need to get a carrier that fits the lower gear sets.

 

 


| All Rights Reserved 2007 - 2022 | www.TB4WD.com |