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In late 1995, Advance Adapters, Inc., sought to venture
into the ultra low 4WD gear business to satisfy the high demand that 4WD
enthusiasts were looking for. With various low gear units out on the
market already, we wanted to design a product that was unique - something
we felt would command a market of its own. We heard of tooling and some
components that were available from the early Ford Courier 4WD
conversions. We felt that buying the tooling and the engineering would be
a fast start for developing a low gear ratio transfer case. |
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| Prototype unit. We called it "the
peanut" case because of it's shape. |
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The tooling was purchased from a gentleman
in Ohio. From that point on, we began incorporating new features into the
Atlas transfer case. One of the first things to be added were
synchronizers to allow "shift on the fly" capability, combined with a new
lower ratio by utilizing a full gear set. Included in this new transfer
case would be a much needed heavy duty rear output shaft. Based on our
acquired tooling, we targeted Wranglers, and early Broncos, which are of
the "left hand" drop configuration. As we took into consideration these
changes, we soon found that the tooling we purchased would be limiting. We
needed a more versatile design allowing us to also include the right hand
drop applications (CJ's), as well as early and late model left hand drop
applications.
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With the original reworked tooling, we had produced 5
prototype units that we shipped out to chosen candidates for testing.
Reports back from one prime candidate, who has a well know early Bronco,
warranted the demand for a totally new design and tooling. After his first
few trails we were not surprised to hear of a broken prototype. We
immediately received this unit back for analyzing and found that the gear
design was marginal. |
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To quickly get our candidate back on the trails, we
shipped out another prototype unit. In the meantime, we began redesigning
the Atlas to withstand the abuse that these units would be subjected to.
This meant redesigning the case of the Atlas to accommodate larger gears
and eliminating the original reworked tooling. Just about the time we had
the Atlas I completed, we were assured of being on the right track when
the second prototype failed in the burly Bronco. (He had now cracked two
"peanuts"!). Fortunately, we were ready to ship the first totally new
Atlas I to rescue the "peanut". Continuing close contacts with our Bronco
test pilot, we are pleased to report no failures. Now, he says he is
breaking other weak links like Dana 60, 35 spline axles!
With the Atlas I in production, Advance Adapters
purchased a prototype vehicle of their own to aid in the further
refinement of the Atlas I transfer case. This was a 1989 Jeep YJ with a 6
cylinder and Torqueflite automatic transmission. As we started installing
the Atlas I into the vehicle, we realized our next set of challenges to
overcome. In trying to produce the Atlas I for a wide range of vehicles,
we overlooked the front driveline clearance on this particular vehicle. We
lacked about a 1/2" of clearance on the Torqueflite transmission pan and
had some problems with the shifter linkage serving this vehicle. To remedy
these problems, we opted to retrofit a GM TH350 automatic replacing the
Torqueflite to allow the Atlas I to be installed in this vehicle. |
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Knowing that we had to make provisions for front
driveline clearance and shifter linkage, we opted once again to do some
fine tuning on the Atlas I. We found that the Jeep automatics were going
to be a popular application, so we decided to stretch the case 1" from
centerline to add clearance for the front driveline. At the same time, we
redesigned the shifter linkage to accept a modular twin stick design for
the Atlas consumer. As we stretched the unit, we utilized the added space
by enlarging the gears, creating a super strong transfer case. |
The Atlas II was then created
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With the Atlas II now in production, we were presented
with some new applications. The Jeep Wrangler TJ series seemed to be a
popular application. We were concerned with the shifting mechanisms
fitting into the new TJ consoles, so Advance Adapters purchased a 1998 TJ
for prototyping the Atlas II and to obtain the proper shift linkage
configuration. This application and installation is previewed in the Jeep
TJ Installation section of the Atlas Manual. |
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The Atlas II has proven to answer the gearing requests
that the 4WD enthusiast was looking for. Although the unit was originally
designed around the Jeeps and early Broncos, now the universal design of
Atlas II enables it to fit a wide range of vehicles. Offered are two new
super strong ratios of 3.8:1 low range and a 4.3:1 extreme trail ratio.
Since then, numerous upgrades have been incorporated
and a wide variety of ratio options have been designed to accommodate any
type of drivetrain combination. The Atlas 2 speed ratios include: 2.0,
3.0, 3.8, 4.3, 5.0 & 6.0. |
Phases of design and development
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peanut prototype |

Atlas 1 |

Atlas 2 |
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Along with these 6 different ratio options, we are now
producing our new 4 speed Atlas Transfer Case. Atlas 4 speed ratios
include: (1.0:1 / 2.0:1 / 2.72:1 / 5.44:1) OR (1.0:1 / 2.72:1 / 3.8:1 /
10:34:1) |
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The Advance Adapters gear-driven transfer cases are the ultimate in gearing
and strength. With over 7000 units sold, the Atlas 2 speed is the solution
for combining both on and off-road performance. The Atlas II from Advance
Adapters offers a solid, one- piece case design and is manufactured from 356
T-6 heat treated aluminum alloy. The massive gears are helical cut and
synchro-equipped for “shift-on-the-fly” capability. These gears are
available in six different low range ratios (2.0:1, 3.0:1, 3.8:1, 4.3:1,
5.0:1, 6.0:1) and are supported by needle bearings, precision matched to
8620 shafts. The 32 spline 1 3/8” output shafts are supported by large taper
bearing sets. The Atlas also features a unique twin stick design that offers
multiple shift positions for neutral, 2wd high,4wd high,2wd low (rear), 4wd
low, 2wd low (front).*front dig*
The Atlas 2 speed and 4 speed transfer cases is sure to bring you the utmost
in dependability and performance with the best warranty in the industry. The
Atlas transfer cases are guaranteed against defects in workmanship and
materials for the life of the original purchaser. This lifetime guarantee
covers and is limited to gear sets and castings. The remainder of the unit
is covered by their limited 1 year warranty.

This Atlas !! is bolted to the ZF 5 speed

FREE
speedo cable with any ATLAS Transfercase.
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The 4 speed has essentially two parts. The first is the reduction housing
This housing holds a 6 gear planetary assembly that has a low range of
2.72:1 and a 1:1 in high range. We use a planetary assembly that was
originally run in a NP241-HD transfer case. This assembly has been rated to
withstand 5,555 ft/lb of torque and up to 11,000 lbs gross vehicle weight.
The second part of the 4 speed may look the same as the standard 2 speed
Atlas, but it does have some differences. The main case of the 4 speed is
the same raw casting, but has some machining variations to make it into a 4
speed. The main case functions independently from the front reduction
housing and retains all of the normal Atlas features.
When all this is put together, you get a new legendary Atlas transfer case
with the best combination of gear ratios ( 1:1, 2.0:1, 2.7:1 & 5.4:1 ) or (
1.1, 2.7:1, 3.8:1 & 10.3:1 ).
The Atlas 2 speed and 4 speed transfer cases is sure to bring you the utmost
in dependability and performance with the best warranty in the industry. The
Atlas transfer cases are guaranteed against defects in workmanship and
materials for the life of the original purchaser. This lifetime guarantee
covers and is limited to gear sets and castings. The remainder of the unit
is covered by their limited 1 year warranty.
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