Transfer Case Upgrades, Modifications, and Options

We get a lot of email from fellow Jeepers wanting to know what the options are for killer transfer cases. Some are looking for strength while others are looking for low gears. In this article we attempt to uncover all that is out there.

There are several modifications that can be performed on a Jeep transfer case. Most involve replacing the gears in the case to lower the gear ratio to improve slow trail performance. Many of these ratio changes can alter the gears in ranges of 3:1 up to 10:1. Many Jeepers also “clock” the transfer case. This involves rotating the case on the input shaft axis to allow for increased ground clearance under the Jeep’s mid section.

We will cover these on a basis of original Jeep transfer case model.

For more info on the “stock” versions of these transfer case see the Jeep Tech section under Technical and Info

Dana 300 Found in 1980 – 86 CJ Whole Cases Advance Adapters Atlas II 2 Speed Transfer Case Atlas 4sp 4 Speed Transfer Case Case Gear and Shaft Upgrades JB Conversions 4:1 LowMax gear set Front Output Shaft Rear Output Shaft Tera Manufacturing 4:1 Tera Low Advance Adapters Rear Output Shaft Rotation or “Clocking” JB Conversions Rotation Plate Advance Adapters Rotation Kit Shifter Options Advance Adapters Twin Stick Shifter

Dana 20 and 18 Found in 1941 – 79 CJ Whole Cases None Commercially Available Case Gear and Shaft Upgrades Tera Manufacturing 3.15:1 Tera Low Advance Adapters 3.15:1 Low Gears 32 Spline Output Shaft Dana 20 and 18 Intermediate Gear Kit Dana 18 Saturn Overdrive Rotation None Commercially Available

NP231 Found in 1987 – 2006 YJ and TJ Wranglers Whole Cases Advance Adapters Atlas II 2 Speed Transfer Case Atlas 4sp 4 Speed Transfer Case JB Conversions HD Case with Std SYE Case Gear and Shaft Upgrades JB Conversions Slip Yoke Eliminator Super Short Slip Yoke Eliminator Wide Chain Tera Manufacturing 4:1 Tera Low Advance Adapters Fixed Yoke Kit Tom Woods Tom Wood’s NP231 Super-Duty Tail Shaft Conversion Kit