Dear valued customer,

Due to the new California wide shelter at home order, we are now no longer able to operate at full capacity or carry on with business and usual. We will continue to ship orders on a reduced capacity and limited schedule as well as receive and process new orders via our website. We will do our best to answer your technical support and customer service inquiries via email, once again we will be working at a reduced capacity so please bear with us as wait times may be longer than usual. We appreciate your understanding during this very challenging time and value your business.

The Advance Adapters Team.

Atlas 4 Speed Transfer Case Builder (#Atlas4)

Starting at: $0.00

Atlas 4 Speed Transfer Case:

Advance Adapters has built upon the proven design of the Atlas 2, to create the revolutionary Atlas 4sp. No other transfer case on the market today has 3 separate low range ratios built into a single unit. This transfer case was designed for the off road enthusiast that likes to tackle a large variety of terrain with one vehicle. Selecting one low range ratio that works well for mud, sand and rock crawling, is a compromise but the Atlas 4sp overcomes this limitation. One transfer case that is perfectly suited to any terrain that you may want to conquer.

The 4SP has essentially two parts. The first is the reduction housing. This housing holds a planetary assembly that has a gear ratio of 2.72:1 when in "low" range, and a 1:1 in "high" range. It has one shifter coming out of the top to select the desired range. The planetary is not a synchronized shift-on-the-fly design and must be operated when the vehicle is stopped. (The main case still retains the shift-on-the-fly capability just like the standard Atlas). The reduction housing shifter is designed for a cable shifter.

The second part of the 4SP may look the same as the standard Atlas, but it does have some differences. The main case of the 4SP is the same raw casting, but has some machining variations to make it into a 4SP. The main case functions independently from the front reduction housing and retains all of the normal Atlas features (front and rear outputs controlled independently, and the "front only" option). All of the gears are the same. The front output uses all of the same parts along with the cluster.

Ratio's of the Atlas 4Speed are:

1.5:1, 2.72:1, & 4.8:1 Recommended for all applications

2.0:1, 2.72:1 & 5.44:1 Recommended for all applications

2.72, 3.0:1 & 8.16:1 Recommended for all applications

2.72:1, 3.8:1 & 10.34:1 with this low gear ratio, high horsepower engines are not recommended

2.72:1, 4.3:1 & 11.70:1 with this low gear ratio, high horsepower engines are not recommended

The strength of this unit is not an issue. We use a planetary assembly that was originally run in a NP241-HD transfer case. The six planetary gear setup has proven its durability and has been used in countless heavy-duty vehicles. Other attributes to the planetary assembly include a very quiet operation, easy shifting, and low rolling resistance. When all of this is put in front of a legendary Atlas Transfer Case, you get the best combination of gear ratios and reliability.

The 4SP units will fit nearly all applications that the standard Atlas will bolt to. These will include spline counts of 21, 23, 27, 29, 31, 32 and 34. The unit has a circular bolt pattern on the front, identical to the one found in Jeep, Ford & Dodge vehicles. We have a variety of different adapters available to retrofit the 4SP into nearly any application. The twin sticks for the main unit can be either the standard linkage or the cable linkage. The standard linkage is offered in a variety of custom packages available for particular vehicles and can be modified to fit many custom applications. The installation of an Atlas 4 speed should be nearly the same as the standard Atlas 2 speed. The Atlas 4 speed is just a bit longer.

We do not recommend flat towing vehicles equipped with the 4 speed due to the additional bearings used in the planetary housing.

Since every Atlas transfer case is custom built to order, the unit will be customized to your vehicle. Please browse this site or give us a call to determine how to configure the ultimate transfer case, and have us build you one for your vehicle.

  • Current Average Estimated Wait Time for New Orders - (5-7 Weeks)


2. Atlas Transfer Case - 4 Speed Units

3. Atlas T/C - Gear Ratio Options

Atlas T/C - Input Shaft splines with Adapter Options

5. Atlas T/C - Rotation & Clocking Options

8. Atlas T/C- Speedometer Options

7. Atlas T/C - Yoke Options

6. Atlas T/C Tailhousing Options

Top Reviews


by George Sabat, from Ontario, Canada

Thank you AA!

I have been in the four wheeling scene for over 15 years, I have owned several stock application transfer cases in my different jeeps and off-road buggies. Recently, I have been building a new rock-crawler chassis and I finally can afford buying the atlas 4sp. Even though there was a wait time to get it, I could not have been happier with my decision, Advance Adapters is a great company to deal with, and I am extremely pleased with my purchase.

1238 of 2400 people found the following review helpful.

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