|Ever since I grenaded my stock transfer case back in '96 I was looking
forward to a heavy duty replacement for the BW 13-54. The 13-54 is a light
weight chain driven unit which does fine in all, but the most extreme off-road
One day while browsing the 4x4NOW website I saw that Mike Partridge,
General Manager of Advance Adapters
was going to be available on the "Ask the Expert" forum. I used this opportunity
to ask Mike if he had plans for the highly renowned Advance Adapters, Atlas
II transfer case to be available for our Ford Explorers. I told Mike about
this website and about all of the people who were very serious about making
their Explorers off-road worthy. Mike told me he would research the market
to see if there was interest.
Fast forward to the 1999 SEMA show in Las Vegas, Nevada. I met Mike
in person at the Advance Adapters booth. I introduced myself and gave Mike
my card. He remembered me from our online discussion and told me that the
Atlas II was being built for the Ford Explorer, I was super happy to hear
this great news. Upon returning from the SEMA show I announced the availability
of the Atlas II.. It wasn't very long before Paul Bredehoft, one of the
regulars on this website, bought the first Explorer based unit. A 3.8:1
unit which is optimal for an automatic equipped Explorer.
The Atlas II is available in two configurations. "Ultra-low" 3.8:1 and
"Extreme-low" 4.3:1. The 3.8:1 ratio is recommended for those with automatic
transmissions as the 4.3:1 is so low the stock brakes would not be able
to hold the Explorer back at an idle. With a manual transmission this is
not a concern because you can simply disengage the clutch and come to a
complete stop. For full technical details check out this page: Atlas
Installation Procedure: For '93 Explorer
w/ manual transmission
1. Given the height of my truck (5.5" lift) there was no need
to put the truck on jack stands. First I placed a floor jack under the
transmission. Next I pulled the drive shafts, transmission cross member,
stock shift lever, speedometer cable and the wiring from the stock transfer
case. At this point I supported the transfer case with another floor jack
and removed the 5 bolts holding it in place. Once the bolts were removed
I worked the transfer case free from the transmission adapter. I lowered
the transfer case with the floor jack and slid it out from under the truck.
2. I setup the shifters on the Atlas II out of the chassis as
the Advance Adapters manual suggests. This is to get the basic adjustment
down and to get a feel for the way the assembly fits together. Once I had
the shifters set up (10 minutes), I broke down the assembly except for
the long threaded rod, and the gold shifter ends.
3. I used my 2-1/2 ton hydraulic jack to raise the Atlas II close
to its mounting point. Care needed to be taken to feed the shift rail (long
threaded rod) up and over the transmission adapter. I needed to leave clearance
between the top of the transfer case and the floor. That's because the
transfer case was being lifted in perfectly flat and once the splines were
engaged and the case was mated with the adapter the case needed to be rotated
for the bolt holes to line up. It required a bit of wrestling to get the
splines mated, but it went together pretty easily.
4. I have the second Atlas II ever to be sold for an Explorer.
Paul Bredehoft has the first. Both of our transfer cases were shipped with
the wrong studs, they shipped studs with SAE threads instead of Metric
which is what's needed. The original bolts from the 13-54 are slightly
too long to thread fully into the Atlas II. I needed to get some new bolts
or studs. Note: I have spoke to Mike Partridge and he is aware of
the situation. He is now shipping the unit without studs and recommends
that the original bolts be cut. My personal recommendation is to buy shorter
bolts. My local Ace Hardware had metric bolts which were about 1/4 - 5/16"
shorter. These fit perfect and it saves from having to cut and use a die
to clean up the threads on the stock bolts. While you're waiting for your
Atlas II to arrive from the factory you could pull an easy to reach bolt
and use it to find a slightly shorter set at a hardware store.
Custom cross member
5. Reinstall the cross member and transmission mount.My transmission
cross member was custom built after my troubles at the Truckhaven pre-run.
The new cross member lowered the transmission quite a bit. This worked
out great with the Atlas II. I bolted everything up and there is plenty
of clearance all around the T-Case even though it's larger than the
stock unit. You will find that you will either need to modify your cross
member, build a new one, or use a 1" body lift to gain sufficient clearance
between the new transfer case and the floor board.
Notch was made for shifter
View from opposite side
6. The stock Explorer uses a CV on it's front drive shaft. The
Atlas II didn't come equipped with a CV yoke on the front so a new drive
shaft was made to the correct length (in this case 29"). My drive shaft
shop, Dick's Drive shaft in Phoenix, assured me that the single U-joint
setup would allow more flex than the CV type, so that's what I used. The
rear yoke on the Atlas II is a CV type yoke. Once again the CV is not needed
so the rear drive shaft was cut to the correct length and fitted with a
1310 slip yoke made for extra articulation. A 1310 strap kit was used to
hold the front U-joint in place. The standard 1310 strap is a tight fit
in the CV yoke. I told Mike about this and he told me that he has a supplier
for special straps which are made specifically for this situation. Mike
is sending me the new straps and he plans to include them in future kits.
All of my U-joints are now "Brute Force". The drive shafts were installed
at this point.
Shifter rods as seen from
Finished interior, nice
7. While the T-Case was still in place I used my friends Sawzall
to notch the drive shaft tunnel for shifter clearance. The shifter handles
which they included were pre-bent for the Explorer. They would have worked
fine with an automatic transmission, but the shifter for the rear axle
was making contact with my 5 speed shifter handle. The fix was easy enough,
I just bent the rod with a long pipe to create additional clearance. I
completed the installation of the shifter linkages per the instruction
manual and was ready to button up the installation.
8. The final details included patching the drive shaft tunnel
with a piece of sheet metal. I cut the metal to size and used sheet metal
screws to hold it in place. Black silicone was used to prevent rattles
and to keep heat out. I installed the shifter boot which was included with
the Atlas II. Next I had to remove the original transfer case shifter boot
from the stock assembly and cut the left side and the bottom from the stock
trim piece. I then fed the 5 speed shifter boot over the handle and the
Atlas II dual stick boot now protrudes from where the stock shifter used
The optional fluid level
site kit is shown here
I have been off-road with the Atlas II a several times now. All I can
say is WOW. Actually I can say more. There's a hill close
to my house which has lots of whoop-dee-doos all the way up. It stretches
the suspension pretty well as one tire goes into a hole and the other gets
picked up by a berm. Anyway I dropped it into low range at the bottom of
the hill and placed the transmission in first gear. I let out the clutch
and let the truck IDLE all the way to the top! The RPM's barely rose to
over 500 yet the progress of the Explorer never slowed.
This deep of a low range isn't for everyone. You give up speed on the
trail (at least in low range, high range remains the same) for extreme
torque and throttle control. The manual transmission is much easier
to control on obstacles with the deep low range. Rock crawling has become
a pleasure instead of a chore. Let the clutch out slowly in lowrange and
get ready to move without the need for slipping the clutch. Obstacles which
used to require revving the engine and slipping the clutch are now accomplished
with no slippage at all.
On the highway, I immediately noticed the lack of backlash that was
present with the stock chain drive case. It also feels like a few extra
horsepower have been freed up. This could be due to the gear to gear design
and the use of bearings throughout the case.
Shifting takes getting used to, but once you learn the system it's extremely
easy and has a very positive feel. From the look and feel of the unit I
believe it's going to be an excellent long term investment.