Choosing a Gear Set:
Since there are numerous engine, transmission, and axle combinations, the need for various transfer case gearing options has increased. The 2 speed Atlas transfer case has 6 different low gearing options to suit the needs of your driving habits and your drivetrain components.
We also offer our 4 speed Atlas transfer case. The 4 speed Atlas gives you 3 low ranges & 1 high range - a few more choices when it comes to 4-wheeling. You can now have the ultra low gearing for rock crawling, a low range gear for trail use, and mid range for sand and mud.
The wide variety of Atlas gear ratio options have been designed to accommodate any type of drivetrain combination. Please be aware that the lower the final drive ratio gets, the harder it is to stop the vehicle when in gear. Larger brakes will be required to slow the vehicle. Shifting the transmission into neutral on an automatic or depressing the clutch on a manual will be required to bring your vehicle to a complete stop.
Atlas Ratios
1.5:1 : This is a newer ratio that looks like it will be more popular for the 4 speed and used in quite a few competition rigs as a 2 speed. 1.5:1 This ratio is offered for both 2 speed and 4 speed transfer cases. The Atlas 4 speed would have the following gearing options: 1.0:1, 1.5:1, 2.72:1, 4.08:1.
Atlas15-G2: includes 5 gears which consist of an input P/N 309115-FFA, front output P/N 309315-FFA, idler gear P/N 310415-FFA, and 2 low speed gears P/N 309515-FF.
Atlas15-G2SF: includes 5 gears which consist of an input P/N 309115-SFA, front output P/N 309315-SFA, idler gear P/N 310415-SF, and 2 low speed gears P/N 309515-SF.
2.0:1 : This unit is more of a stock ratio found in most early full size trucks and used in quite a few competition rigs. 2.11:1 This ratio is offered for both 2 speed and 4 speed transfer cases. The Atlas 4 speed would have the following gearing options: 1.0:1, 2.11:1, 2.72:1, 5.44:1.
Atlas20-G3: includes 5 gears which consist of an input P/N 309115-FFA, front output P/N 309315-FFA, idler gear P/N 310420, and 2 low speed gears P/N 309530-FF.
Atlas20-G3SF: includes 5 gears which consist of an input P/N 309115-SFA, front output P/N 309315-SFA, idler gear P/N 310420-SF, and 2 low speed gears P/N 309530-SF.
3.0:1 : This unit is popular in numerous applications. Used in quite a few competition rigs. 3.03:1 This ratio is offered for both 2 speed and 4 speed transfer cases. The Atlas 4 speed would have the following gearing options: 1.0:1, 2.72:1, 3.03:1, 8.16:1.
Atlas30 (trail): includes 5 gears which consist of an input P/N 309130-FF, front output P/N 309330-FF, idler gear P/N 309430-FF, and 2 low speed gears P/N 309530-FF.
Atlas30-G2: includes 5 gears which consist of an input P/N 309130-FF, front output P/N 309330-FF, idler gear P/N 310430, and 2 low speed gears P/N 309530-FF.
Atlas30-G2SF: includes 5 gears which consist of an input P/N 309130-SF, front output P/N 309330-SF, idler gear P/N 310430-SF, and 2 low speed gears P/N 309530-SF
3.8:1 : The Atlas 3.8 is a good choice for the avid 4-wheeler since this low gear ratio is ideal for moderate to some extreme rock crawling. 3.824:1 This ratio is offered for both 2 speed and 4 speed transfer cases. The Atlas 4 speed would have the following gearing options: 1.0:1, 2.72:1, 3.8:1, 10.34:1.
Atlas38 (trail): includes 5 gears which consist of an input P/N 309138-FF, front output P/N 309338-FF, idler gear P/N 309438-FF, and 2 low speed gears P/N 309530-FF.
Atlas38-G2: includes 5 gears which consist of an input P/N 309138-FF, front output P/N 309338-FF, idler gear P/N 310438, and 2 low speed gears P/N 309530-FF.
Atlas38-G2SF: includes 5 gears which consist of an input P/N 309138-SF, front output P/N 309338-SF, idler gear P/N 310438-SF, and 2 low speed gears P/N 309530-SF.
4.3:1 : This unit is popular in numerous applications. 4.286:1 This ratio is offered for both 2 speed and 4 speed transfer cases. The Atlas 4 speed would have the following gearing options: 1.0:1, 2.72:1, 4.3:1, 11.69:1.
Atlas43 (trail): includes 5 gears which consist of an input P/N 309143-FF, front output P/N 309343-FF, idler gear P/N 309443-FF, and 2 low speed gears P/N 309530-FF.
Atlas43-G2: includes 5 gears which consist of an input P/N 309143-FF, front output P/N 309343-FF, idler gear P/N 310443, and 2 low speed gears P/N 309530-FF.
Atlas43-G2SF: includes 5 gears which consist of an input P/N 309143-SF, front output P/N 309343-SF, idler gear P/N 310443-SF, and 2 low speed gears P/N 309530-SF.
5.0:1 : This unit is popular in numerous applications. 5.048:1 This ratio is offered for a 2 speed only. The Atlas 4 speed is not a option with this gear set.
Atlas50 (trail): includes 5 gears which consist of an input P/N 309150, front output P/N 309350, idler gear P/N 310450, and 2 low speed gears P/N 309550.
With any of the Atlas ratios equipped in your 4WD, you have the opportunity to select a sensible ring and pinion gear ratio for great street performance. Combined with a low-geared crawl ratio of your choice, your vehicle will have the ultimate combination. This allows you to compete with the most well-equipped vehicle, but then be able to cruise comfortably down paved roads. If you are serious about on and offroad performance and dependability, then demand one of the Advance Adapters Atlas transfer cases.
All of the gear sets above except for the 1.5:1, 2.0:1 and the 5.0:1 are available in both strength grades, a Trail Series and a G2/G3 Pro Rated Series.
- Trail Series gear sets: The tried and true Atlas gears that we have been producing for years. These gears will take plenty of punishment are perfect for everyday off road use and abuse. This gear set has the 1.25" idler shaft.
- G2/G3 Pro Rated Series gear sets: These are for the hardcore off road enthusiast or competitor who wants and needs the very best, and tend to punish and push their equipment to the limits day in and day out. These gears come in either a "super finished" state indicated by the(SF) in the part number or the standard finish. These gears all come with an 1.5" idler shaft.
- 109% increase in beam strength, 7% dynamic/15% static load rating bearing sets, 25% thrust surface area for higher thrust loads, 7% reduction in weight
- The super finished gears provide a number of benefits: less friction / lower operation temperatures, extended component life, increase efficiency & reduce lubrication requirements.
Obsolete Gear Sets
2.09:1 This gear set was the early 2.0:1 ratio but was updated in April of 2014. The updated gear set added strength to the 2.0 ratio, however, the new design was not interchangeable with this gear set. This ratio 2.09:1 is an obsolete gear set for new units but we still offer gears replacements for old Atlas transfer cases. Input P/N 309120-FF, front output P/N 309320-FF, idler gear P/N 310420-FF, and 2 low speed gears P/N 309520-FF.
Please call and check availablity on any of the 2.09:1 gears.
6.00:1 This gear set was discontinued in November of 2007. we no longer have any of these gears available.