By
building a strong aluminum adapter plate, Marlin
Crawler is able to bolt an additional reduction
housing unit between your existing transfercase
and transmission with each case having its own
shifter. By combining the factory Toyota transfercase
low range reduction gear sets of 2.28:1, a final
transfercase ratio of 5.2:1 is achieved. This
new low range gear ratio is 119% lower than
a stock setup.
Each of the two reduction housings
can accept either the stock, 4.00:1, or our
Marlin Crawler 4.70:1 gear
set. With the dual case setup you will also
have access to 2WD low range, which is very
useful on the trail between major obstacles,
or while towing boats out from steep lake docks.
Having dual cases gives you access to 20 forward
gears and 4 different reverse gears (with a
5-speed transmission).
The second case and adapter
plate measures to only 6 ½" long. Except
for reworking the drive shafts, it's a fairly
easy installation. The adapter flanges are 5/8"
thick. The cross member is able to remain in
its original factory mounting location. Depending
on the application, the second shifter rests
6½" to 11" behind the transmission,
and the third shifter will rest 6½" to
10" behind the crawl box. Other locations
for the second shifters are available by using
Off-Set shifter kits
and Short Throw shifter
kits.
In our opinion, the Ultimate
setup is when a dual transfercase is built with
one set of stock gears (2.28:1), and one set
of Marlin Crawler's 4.70:1
gear sets. This is known as the Dual
Ultimate Crawler. In a 21-spline
application, due to the excess torque generated
by the 4.70:1 gears, we will only build a 21-spline
Ultimate Crawler with the 4.70:1 gears in the
back case. But in a 23-spline
application, the factory 23-spline input
is much stronger, and therefore, the 4.70:1
gears can be placed in either the front case
or in the rear, the choice is yours. In any
of the available applications, two sets of
4.70:1 can be used to achieve a low range crawl
ratio of nearly 500:1! More than 9 times lower
than stock!We call this a Dual Ultimate
Overkill Crawler since such a low crawl ratio
is merely for bragging rights.
Beauty of Two Shift Levers
 With
a dual transfercase setup, the front shifter
is simply a high/low shifter. High range is
1:1, and Low range is 2.28:1 (or 4.00:1 or 4.70:1).
The rear shifter is the same "J" pattern
you have now, with High range as 1:1, and Low
range as 2.28:1 (or 4.00:1, or 4.70:1).
With the addition of just the
Marlin Crawler Dual Transfercase Crawler to
your vehicle, you have the ability to leave
one shifter in Low Range, and the other in High
Range. And as you might have guessed, this would
be the same ratio that you are now. So you would
still be able to keep up with your friends when
you come to these long flat dirt stretches between
obstacles. And then, with the push of the second
lever into Low Range, a new transfercase overall
ratio of 5.20:1 enables your vehicle to crawl
at gear ratios only dreamt of.
With a Marlin Ultimate Crawler
setup you can place one case in low range (2.28:1)
and use stock 4WD low range. You can also use
just the 4.70:1 gears and keep the other case
in High range, giving you just over twice the
low range gearing of stock. For the really tough
trails, or whenever the trail demands more torque,
traction, timing, or control, you can put both
cases in low range and have 4.5 times the reduction
of the stock case.
The ability to shift each lever
separately gives you the following low range
options:
| Setup |
Overall T/case ratio, low range |
| Stock
4 Cyl |
2.28 |
| Stock
6 Cyl |
2.57 |
| Single
case with 4.70 gears |
4.70 |
| Dual
case / stock gears (2.28 & 2.28) |
2.28
and 5.20 |
| Dual
case / stock (2.28) and 4.70 gears |
2.28
and 4.70 and 10.70 |
| Dual
case / two sets of 4.70 gears |
4.70
and 22.09 |
| Triple
cases can also be done |
2.28,
4.70, 5.20, 10.70, 22.09, and 50.36 |
Crawl
Ratio Table
| This chart helps
you to see all the common crawl rations
available from stock and modified dual crawlers.
Start by finding the column with your ring
and pinion ratio at the top. All ratios
are based on a 3.93 first gear ratio, the
most common Toyota 4WD first gear transmission
ratio. Other common Toyota first gear ratios
are 3.83, 3.95, 4.31, and 5.15 Ring
& Pinion
T/Case
Gears |
3.90 |
4.10 |
4.37 |
4.56 |
4.88 |
5.29 |
| 2.28 |
35 |
37 |
39 |
41 |
44 |
47 |
| 2.57 |
39 |
41 |
44 |
46 |
49 |
53 |
| 4.70 |
72 |
76 |
81 |
84 |
90 |
98 |
| 2.28
X 2.28 |
80 |
84 |
89 |
93 |
100 |
108 |
| 2.28
X 4.70 |
164 |
173 |
184 |
192 |
206 |
223 |
| 4.70
X 4.70 |
338 |
356 |
379 |
396 |
424 |
459 |
|
Additional Information:
|
