Atlas 4 Speed Transfer Case Builder (#Atlas4)

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 a low range, and a 1:1 in a 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 a front only option). All of the gears are the same. The front output uses all of the same parts along with the cluster. 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 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. CASE: Material: 356-T6 Heat Treated Aluminum Weight: 125 lbs. (dry) INTERNAL COMPONENTS: Gears: Helical Cut Planetary Gears: 6 Gears Helical Cut Bearings: Needle & Taper Rollers Synchronizers: Borg Warner Available Input Shaft Splines: 23, 27, 29, 31, 32, 34 Tail Shaft H.D., 32 Spline Front Output 32 Spline

RATIOS:

Low Range:1.5:1, 2.72:1, & 4.08:1 or

2.0:1, 2.72:1, & 5.44:1 or

2.72:1, 3.0:1, & 8:16:1 or

2.72:1, 3.8:1, & 10.34:1

2.72, 4.3:1, & 11.69:1

To start your order of a new Atlas 4 speed Click Here

High Range 1:1 LUBRICATION: Quarts: 2.5 Liters: 2.36 We are currently shipping Redline 75W-90 GL4 with all new Atlas units, this along with the other lubricants that are printed in our Atlas Installation Guide are the recommended fluids for the Atlas. LENGTH COMPARISON: *Atlas Short tailhousing is 16.75" *Atlas Long tailhousing is 18.75"

New Process 231 is 20.5"

New Process 241 Rock Trac T/C is 15-1/4"

Dana 300, 12"

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 now has 6 different low gearing options to suit the needs of your driving habits and your drivetrain components. Along with the these different Atlas 2 speed ratio options, we are now producing our new 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. Whether you're looking at the 2 speed Atlas or the 4 speed Atlas, your ratio options will be diverse.

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 2 Speed 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.

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

3.0:1 : This unit is popular in numerous applications. Used in quite a few competition rigs

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.

4.3:1 : This unit is popular in numerous applications.

5.0:1 : This unit is popular in numerous applications.

Atlas 4 Speed Ratios

1.0:1 / 2.72:1 / 1.50:1 / 4.08:1

1.0:1 / 2.72:1 / 2.00:1 / 5.44:1

1.0:1 / 2.72:1 / 3.00:1 / 8.16:1

1.0:1 / 2.72:1 / 3.80:1 / 10.34:1

1.0:1 / 2.72:1 / 4.3:1 / 11.69:1

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 and the 5.0:1 are available in two strength grades, a Trail Series and a Pro 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.

• Pro 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.

Choosing the Proper Input Shaft:

There are currently over 20 different Atlas input shafts in production today, varying in length and spline count. To completely understand your particular need when it comes to Atlas inputs first you have to look to the transmission that it will be mating to, and if any special adapters will be needed. Below is a list of the most popular transmissions currently being used today and the requirements for mating up to the Atlas. If your application is not listed below, it does not necessarily mean that we don’t have anything for you, it just may take a little more work to make it happen and will require call for further assistance.

Jeep Transmissions

GM Transmissions

Ford Transmissions

Dodge Transmissions

Choosing a Case Rotation:

When making the decision on what case rotation is best suited for you're vehicle there are a few things to consider:

• What side is your front differential on?

This will determine if you are in need of a passenger or a driver side drop case.

• What angle would you like the case to hang at?

In some cases the preference would be to have the case sit as close to level as possible, however in some applications this is just not possible due to clearances or interference issues.

OPTION #1

This stock transmission bolt pattern is found on transmissions that were originally bolted to a Dana 300 transfer case with a stock case rotation of 35 degrees. This stock transmission bolt pattern is also found on some Jeep transmissions when bolted to a New Process transfer case that had a stock rotation of 23 degrees. Atlas rotation option 1

Atlas 2sp Left Drop 0, 18, 25, 32, 39, 46 Degrees

P/N ALC-T (Trail Case)

P/N ALC-G2 (Pro Case)

P/N ALC-D (Divorced Trail Case)

P/N ALC-G2-D (Divorced Pro Case)

P/N ALC-43F-G2 (Ford 6R140 transmission case assy. Pro Series)

P/N ALC-G2-FT (Flat Tow case assy. Pro Series)

Atlas 2sp Right Drop 5, 12, 19, 26 Degrees

P/N ARC-T (Trail Case)

P/N ARC-G2 (Pro Case)

P/N ARC-D (Divorced Trail Case)

P/N ARC-G2-D (Divorced Pro Case)

Atlas 4sp Left Drop 0, 17, 24, 31, 38 Degrees

P/N A4-LC-G2 (Pro Case)

P/N A4LC-G2-FT (Flat Tow case assy. Pro Series)

Atlas 4sp Right Drop 5, 12, 19, 26 Degrees

P/N A4-RC-G2 (Pro Case)

OPTION #2

This stock transmission bolt pattern is found on some Jeep transmissions when bolted to a New Process transfer case that had a stock rotation of 13 degrees. Atlas rotation option 2

Atlas 2sp Left Drop 0, 8, 15, 22, 29, 39 Degrees

P/N ALC-T (Trail Case)

P/N ALC-G2 (Pro Case)

P/N ALC-D (Divorced Trail Case)

P/N ALC-G2-D (Divorced Pro Case)

P/N ALC-43F-G2 (Ford 6R140 transmission case assy. Pro Series)

P/N ALC-G2-FT (Flat Tow case assy. Pro Series)

Atlas 2sp Right Drop 0, 15, 22, 29, 36 Degrees

P/N ARC-T (Trail Case)

P/N ARC-G2 (Pro Case)

P/N ARC-D (Divorced Trail Case)

P/N ARC-G2-D (Divorced Pro Case)

Atlas 4sp Left Drop 6, 13, 20, 27 Degrees

P/N A4-LC-G2 (Pro Case)

P/N A4LC-G2-FT (Flat Tow case assy. Pro Series)

Atlas 4sp Right Drop 5, 15, 22, 29, 36 Degrees

P/N A4-RC-G2 (Pro Case)

OPTION #3

This bolt pattern is found on most of our adapter housings. If you are currently using one of our castings equipped with the dual bolt pattern, you will have all the options listed above.

Atlas rotation option 3

Mechanical Speedometer Housing

he Atlas Standard 32 Spline tailhousing is the only housing that offers a speedometer option. The Atlas Standard 32 Spline tailhousing is designed to fit a stock Jeep (1982 & up) mechanical driven speedometer housing. These housings drive a cable that operates the speedometer. This speedometer housing is from a 1983 to 1986 Jeep CJ. The speedometer gear is not included with this housing, but by using the charts (Fig. E) that follow you can select the correct gear for your tire size and axle ratio. Some of these gears are hard to come by, so we may not offer the gear for your application. Note: The mechanical speedometer housing use the long style pinion gears. (pinion gears are not included with housing, however may be purchased separately) PN300620

Plug The Speedometer Hole

If your application does not require any speedometer connections, we also offer a plug for the tailhousing to keep any dirt and debris out of the transfer case, and provide a sealed environment. PN300621

Electronic Style Speedometer Housing

The Atlas only accepts the mechanically driven YJ & TJ Speedometer. The late model Jeep TJs with the Rock Trac 241J transfer case used a tone ring and sensor for the speedometer pickup source. This combination is not able to be used on the Atlas tailhousing. The earlier NP231 style speedometer will work the same as the later model tone ring and sensor. One advantage is the mechanical unit is easy to modify when larger tires or different ring and pinions are used. The charts (Fig. E) that follow offer different drive gear part numbers to calibrate your speedometer. Note: The electronic speedometer housing use the short style pinion gears.(pinion gears are not included with housing, however may be purchased separately) PN300637. Tire diameter is figured with the actual tire diameter not the size listed on the side wall. Most tires are smaller in diameter than the size printed on them.

Speedometer Calibration Chart

Ford Full-size truck & Bronco 87-91speedometers:

Regardless if your speedometer is mechanical or electronic, you must use our PN301506.

If you have a mechanical cable driven speedometer, a custom cable will need to be made. The 301506 has a 7/8" thread and the Ford is a metric thread. If your stock unit had a electronic set up, a cable adapter can be used from the 7/8" thread to a pulse generator that will send the computer the correct pulse needed. Both the mechanical and electronic components can be obtained from Nevada Speedometer 775-358-7422.

Toyota Speedometer Cable Adapter 1995-97:

This cable adapter allows the Atlas speedometer drive housing (P/N 301506) to couple to the stock Toyota speedometer cable. You can then retain the factory gauge and have all the added benefits of the Atlas transfer case. This cable adapter is sold under PN300613 and has a Toyota side- 22mm w/ .203 female fitting, and on the other end couples to the Atlas speedo housing side- SAE 7/8"-18 .104 square.

Toyota Speed Sensor 1998-Newer , FJ Cruisers, T100, Tacoma:

This kit allows you to retain the factory Toyota Vehicle Speed Sensor when installing an Atlas Transfer Case. A speedometer cable is used with a sensor housing to remote mount the VSS that was originally installed in the Toyota transfer case. This kit is sold under PN300605. You will also need the speedometer housing PN301506 for the Atlas and the proper drive gear.

With the Atlas transfer case being such a diverse case fitting into such a wide variety of vehicles, naturally we needed a variety of available transfer case yokes.

All of our yoke options are called out by their series number, and style.

Series Number

The series number is a classification that was standardized by the Spicer corporation that refers to the size of the yokes bearing width and cap diameter.

Yokes we offer are:

1310CV, 32 spline PNA1310CV

1330CV, 32 spline PNA1330CV

1350CV, 32 spline PNA1350CV

1310, 32 spline PNA1310

1350, 32 spline PNA1350

1410, 32 spline strap PNA1410

1410, 32 spline U-Bolt PNA1410U

1310/1330/1350 FLANGE YOKE, 32 spline PNAF1300

(1300 series Flange yoke is drilled and tapped for (4) 1/2"x 20 bolts on a 4.25"diameter,(4) 7/16"x 20 bolts on a 3.50"diameter and has a 2.0" male index for the mating yoke.)

Spicer companion yoke numbers are as follows:

(1310 C.V., P/N 211229x), (1310 non-C.V., P/N 2-2-939), (1330 C.V. - P/N 211631x), (1330 non-C.V., P/N 2-2-1369), (1350 C.V., P/N 212024x), (1350 non-C.V., P/N 3-2-1579).

1350,1410 FLANGE YOKE CV, 32 spline PNAF1350 ( Yoke has a 3.125" male index for the mating yoke.)

1350,1410 FLANGE YOKE non CV, 32 spline PNAF1410

(1410 Flange yoke is drilled and tapped for (4) 12mm x 1.25 bolts on a 3.75"diameter and has a 2.75" female index for the mating yoke.)

1410 non C.V. flange yoke. Spicer companion yoke number is 3-2-1329 (1410 non-C.V.)

1480FLANGE YOKE, 32 spline PNAF1480

TOYOTA FLANGE YOKE (3 BOLT PATTERNS 60mm x 60mm, 64mm x 56mm, & 68.3 x 60mm) PNAFTOY

Flange yoke may require the companion flange bolts to be installed through the yoke before the yoke is installed onto the transfer case. This depends on the series of companion yokes used. If the flange yoke is currently installed on your transfer case, you may be required to first loosen the yoke retaining nut, pull the yoke away from the transfer case enough to install the companion flange bolts. Once the bolts are in place, a new yoke lock nut should always be installed and torqued to 150 ft.-lbs. to secure the yoke to the transfer case.

Size Chart

Yoke Style

The two common yoke styles are CV (Constant Velocity) also referred to a "Double Cardan" and Non-CV. The CV style utilizes a carrier block (Cardan) that contains a set of two bearings, one per side. One side of the carrier (Cardan) is bolted to the transfer case output yoke, capturing a bearing between the transfer case output yoke and one side of the carrier, and the other bearing is captured between the other side of the carrier and the yoke affixed to the drive shaft. This type of yoke setup is most commonly used when attempting to overcome step or compound drive shaft angles.

The Non-CV style yoke uses only one bearing that is secured between the transfer case output yoke and the drive shaft yoke using straps or u-bolts.

Yoke Modifications: Changing the style of yokes on the Atlas transfer case may require your new yoke to be modified. When installed on an Atlas, the yoke will load up against a tapered roller bearing. Some yokes require a chamfer to be machined to clearance the cage of this bearing. All the yokes we offer have this chamfer. Yoke

Advance Adapters has started a change in product design with the mating components of its rear output shaft, front output shafts, and on divorced unit front input shaft. The modifications can be found on the follow instructions. CLICK HERE

Standard Atlas Tailhousing

The standard Atlas transfer case comes with a rear tailhousing that accepts a stock Jeep speedometer from Jeep vehicles 1982 & newer. Atlas units ordered for earlier Jeeps or other vehicles can order a mechanical drive speedometer housing. This housing is the same as an early style Jeep. To connect to this housing, a special cable fitting may be necessary. The speedometer provision on the Atlas also allows you to calibrate your speedometer for tire and gearing changes. This Atlas tailhousing is P/N ALT-T. If a speedometer is not needed, the speedometer access hole can be plugged by using PN300621.

Atlas Short Tailhousing (No Speedometer)

The rock crawling & racing industry drove the demand for the creation of the short tailhousing. We had inquires for new drivetrain combinations, shorter drivetrains and light weight rear engines combinations. With these newer combinations, we were prompted to build a shorter Atlas tailhousing. This tailhousing is 2” shorter than the standard Atlas tailhousing. It is designed for trail or competition use only since it does not provide provisions for any type of speedometer. This new tailhousing can be retrofitted to any Atlas case by ordering PN301499R. If you’re ordering a new case, this item can be included on a new Atlas by using P/N AST-T. Not recommended for street use.

HD Atlas Tailhousings with 300M Output Shaft

The HD Atlas rear tailhousing is basically the same as the standard and short housing with the exception on the output shaft. The output shafts in these tailhousings are manufactured out of 300M steel. This was introduced into our product line for a special aftermarket military vehicle but also used in many of the performance racing applications. This high grade steel shaft is 130% stronger than our standard output. This kit is not necessary for most applications; however, for extreme horsepower and torque this Atlas HD tailhousing may be for you. The HD tailhousing is available for the all Atlas transfer cases at an additional cost, Part No. ALT-G2 or AST-G2.

GM VSS Tailhousing (No Speedometer)

Vehicle speed sensors (VSS) are mandatory for computer controlled engines and transmissions. The VSS sends information to the vehicle computer system for both engine and automatic transmission operations. Early Chevys up to 1992 used a computer that required a D.C. square wave input into the computer. These early computer system requirements could be fed by either a special speedometer drive or a reluctor ring. Chevys 1993 & newer required a A.C. sine wave. This sine wave creates a voltage that increases with vehicle speed. The only way that this voltage can be generated is through a reluctor ring mounted to either the transmission or transfer case shafts. This information was obtained from various sources, so please verify your requirements before doing any vehicle modifications.

Our tailhousing allows a sensor and reluctor to be installed in place of the speedometer drive. Our Atlas tailhousing had to have some slight pattern changes to incorporate this new feature. To add this option to an existing transfer case would require the purchase of a new tailhousing. This new option was primarily developed so that the Atlas could be installed into a newer Chevy 4WD vehicle. When ordering this tailhousing with an Atlas, we also include a standard shift control unit that is drilled and tapped to accept a low range switch. This allows the Chevy computer to re-calibrate the output shaft signal when in low range. Note: The Chevy computer may require some wiring and computer program changes for the different low ratios.

On Vehicles with computer controlled engine swaps, this tailhousing kit can provide the proper VSS signal when using a manual transmission. Vehicles with a computer controlled engine swap and an automatic transmission requiring a VSS should not use this tailhousing option unless a low range switch is installed and the computer program is modified. When installing this type of engine and automatic transmission combination, we highly recommend a reluctor ring location in the adapter or the transmission. This will give the engine computer system a correct 1-to-1 reading in or out of low range.

The VSS tailhousing kit we offer is P/N AVT-T

The VSS tailhousing kit for the 300M is P/N AVT-G2

If you have installed a newer GM engine into a Jeep with a manual transmission, you may want to retain the Jeep speedometer, but the GM engine needs the 40 pulse reluctor to function correctly. The standard Atlas transfer case tailhousing should be retained and one of our TruPulse kits should be used. These TruPulse reluctor kits fit on all of our Atlas tailhousings. These kits are an externally mounted unit that provides the True 40 Pulse required for the computer system. The reluctor ring gets mounted to the transfer case yoke. The kit is offered in several yoke styles. Note: These kits will not work with a flange yoke.

TruPulse Kits:

PN50-5040 with a 1310 non C.V.

PN50-5041 with a 1310 C.V.

PN50-5042 with a 1350 non C.V.

PN50-5043 with a 1410 non C.V.

Flat Tow Tailhousing

Introduced in 2018 the flat tow option was released for the Atlas transfer case. This new option uses a new rear output shaft that is connected to a gerotor pump assyembly. The Atlas pan has a pick up screen that pulls oil from the main case pulling it into the tailhousing and down the output shaft lubricating the bearings while driving and being flat towed. The length of the tailhousing is the same as the standard Atlas. It does not have the mechanical speedometer gear but offers an electronic pick up for a Jeep , GM, or STD which has no pick up.

P/N AFT-JP Flat Tow tailhousing with Jeep sensor

P/N AFT-GM Flat Tow tailhousing with GM sensor

P/N AFT-STD Flat Tow tailhousing witout a speed sensor