|
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 "Hercules"High Impact’s Klune-V / Left Drop Dana 20 comboreplacement for Wrangler NP231 Tcase |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 |
|
or Call 818-517-6145 |
Developed for applications where the top-of-the line
available gearing system is needed. This is what I run in my Grand Cherokee
project vehicle.
Atlas II Transfer case
The Atlas II is the Top-of –the-heap, the culmination
of development in the “low geared transfer case” side of the fence. This
box is all gear drive, no chains. It has all helically cut gears, no
straight cut gears. It comes with a twin stick shifter. It is stout,
stronger than the factory T-cases used in Jeeps and sport utilities, and in
many larger pickups over the years. The case is aluminum, avoiding the
brutal weight of a big stout old time gear drive case, but is thick and
durable, unlike the paper thin aluminum used in most modern T-cases. And it
is fully synchronized, meaning you can shift it on the fly easily. Almost
all T-cases recommend that you stop or almost stop the vehicle before
shifting into or out of low range. The final feature is a big one: The case
was designed to fit almost any vehicle, with left or right drop versions
available, and with different input shafts available to match all popular
transmissions.
Klune-V Extreme Underdrive
This unit is the top of the heap in the “Dual
Transfer Case” group. Actually, it is not a transfer case at all. It is a
purpose and built gear reduction unit designed to bolt in between the
transmission and transfer case of a 4 wheel drive vehicle. It comes in two
versions: The “David” and the “Goliath”. The David uses a
double-compound planetary gear set to achieve a 4 to 1 reduction. The
Goliath is a 2.7 ratio planetary gear reduction. Both models have achieved
an excellent reputation for durability in their application niche. Since the
unit is used in front of the transfer case, it can be shifted in leaving the
T-case in high, or the T-case can be shifted into low leaving the Klune in
high, or they can both be shifted into low, with the Klune box multiplying
the gearing of the transfer case for “extreme underdrive”
Klune-V plus Atlas: The Twain shall meet
In our Grand, we will need it all. (Or at least we want it, and have figured out how to get it. Doesn’t that amount to “Need”?) In our Grand, we elected to shoot for the ultimate by mating an Atlas to a Klune. In order to get the maximum gearing options possible, we selected an Atlas II 4.3 ratio transfer case, and coupled that to a Klune-V Goliath 2.7 ratio unit. When one unit has a much deeper reduction that the other, 4 different gear ranges can be achieved: Normal high range: Both boxes left in high range, axle ratio chosen for optimal highway driving. Shift the Klune into low, and the Atlas into high: Results in a “Normal” 2.7 ratio low range, best for forest trails, mud and sand. Shift the Atlas into low, leave the Klune in high: Now we are 4.3 to one and have the right gearing for good rock trails such as most of the Rubicon. Shift both into low, and you are in “Extreme Underdrive”. Almost 12 to one! This is far too slow for most trail riding, but is awesome for those super technical boulder groupings and “waterfalls”. By slowing it WAY down, we get the control to make it over some pretty tough stuff with a healthy degree of confidence we can make it through and back without breaking, and maybe even keeping the sheet metal off the rocks (tread lightly: don’t want any paint on those rocks!). And if we do have to winch, the tires will turn at winch speed allowing the winch and engine to work together smoothly.
Gear Ratio Tables
| Effective Klune-V / Atlas 3.8 combined Ratios | |||||
| Application | Klune-V "Goliath" | Atlas II 3.8 | Combined | ||
| shift pos | ratio | shift pos | ratio | ||
| Highway | In "Hi" | 1.0 | In "Hi" | 1.0 | 1.0 |
| Trail | In "Low" | 2.7 | In "Hi" | 1.0 | 2.7 |
| Rock | In "Hi" | 1.0 | In "Low" | 3.8 | 3.8 |
| Extreme Underdrive | In "Low" | 2.7 | In "Low" | 3.8 | 10.3 |
| Effective Klune-V / Atlas 4.3 combined Ratios | |||||
| Application | Klune-V "Goliath" | Atlas II 4.3 | Combined | ||
| shift pos | ratio | shift pos | ratio | ||
| Highway | In "Hi" | 1.0 | In "Hi" | 1.0 | 1.0 |
| Trail | In "Low" | 2.7 | In "Hi" | 1.0 | 2.7 |
| Rock | In "Hi" | 1.0 | In "Low" | 4.3 | 4.3 |
| Extreme Underdrive | In "Low" | 2.7 | In "Low" | 4.3 | 11.6 |
 |
|
|
double-click pictures for larger view
Developed
as a replacement for the Wrangler NP231 Tcase, this combo capitalizes on the
early Bronco Dana 20 transfer case. Since this unit is Left Drop, and is only
10,5" long, it puts the front driveshaft on the correct (driver) side for
a Jeep Wrangler, The assembled combo is 18.5 inches long,
from the front mount surface to the center of the rear yoke (Where the center
of the U-joint would be). This is about 3" shorter than the stock NP231
as used in a Wrangler, and is only about 1" longer than an NP231 with a slip yoke eliminator kit on
it! It will bolt in where the stock NP231 Tcase comes out. It comes with 1310 CV type yokes, front and rear. It can be made to work with
the factory Wrangler shifter, by extending the linkage rod.
With this system, you can have four different Tcase ranges to shift between:
1 to 1 high range, 2.46 to one low range (Bronco box in low, Klune in Hi),
4:1 low range (Bronco box in Hi, Klune in Low)
Almost 10 to one low range (Both
boxes in low)
Gear Ratios Table
| Effective Klune-V / Bronco D20 combined Ratios | |||||
| Application | Klune-V "David" | Bronco Dana 20 | Combined | ||
| shift pos | ratio | shift pos | ratio | ||
| Highway | In "Hi" | 1.0 | In "Hi" | 1.00 | 1.00 |
| Trail | In "Low" | 4.0 | In "Hi" | 1.00 | 4.00 |
| Rock | In "Hi" | 1.0 | In "Low" | 2.46 | 2.46 |
| Extreme Underdrive |
In "Low" |
4.0 |
In "Low" |
2.46 |
9.84 |
(calculations based upon 1966-1972 Tcase 2.46 low range ratio. 1973-1977 box has 2.34 low ratio)
Klune/Wrangler
system comparisons:
Stock
NP231: Typically 21"
NP231
with 32 spl Slip Yoke eliminator: 17.5"
Klune/NP231
with slip yoke eliminator: 23.5"
Klune/Atlas
combo: 21.5"
Klune/Dana
300 Combo 19.5"
or 21.5" depending on if D300 has short or long tail housing.
Klune/Bronco
Dana 20 Combo: 18.5"
Frequently Asked Questions:
What is generally involved in installing in a Jeep Wrangler?
Behind stock Jeep transmissions used in Wranglers, the Hercules system will bolt up directly where the NP231 came off. Size and length are slightly shorter than the stock NP231. It will easily fit inside the stock Tcase or even a belly up (The unit comes with the ability to select different Tcase clocking). Shifter, driveshaft and speedo hookup details are covered below.
What do I need to do for a Tcase shifter?
The system as supplied above can be set up to shift the Dana 20 2Hi-4Hi-N-4Lo simply by running a link rod from the stock Wrangler T-case shift lever.
Can I Twin Stick this system?
The system can also be supplied with a Tcase ready to for twin stick operation, The Atlas twin stick shifter lends itself to this operation. The twin stick levers will come out where the stock Wrangler Tcase shifter was. The twin stick system will allow front wheel drive, rear wheel drive or 4WD in any gear range. It is not a completely bolt in set up: You will need to fabricate a bracket to bolt the Atlas twin stick assembly to, off the body or off the tranny tail housing. You then can use all thread to make up a pair of shift rails to shift the Bronco Dana 20. Some external modification to the Tcase shift rails is necessary to do this, Instructions supplied.
Twins Stick Details at Bronco Dana 20 Data sheet
Will I need to Modify my driveshafts?
You will definitely need a CV jointed driveshaft with a slip-yoke in it Front and Rear. It is likely you already have this in the front, however if you still have the stock shaft in the rear, you will need a new rear shaft.
As for length, well it's close. Since you have probably lifted your Jeep, and that has already altered the math from a stock driveshaft application, I cannot say for sure.
In the rear, If you already have a Slip Yoke Eliminator on your 231, you would also have a CV jointed, slip spline type shaft. The shaft will need to get about 1" shorter, typically, although all Slip Yoke Eliminator Kits are not the same size. You may have enough slip in your current driveshaft to accommodate the change without any further correction. Just MAKE SURE the rear shaft will not bottom out under full compression of the suspension. The Hercules system is 18.5" long from the front of the Klune where it bolts to the trans adapter to the center of the U-joint in the 1310 CV output yoke.
In the Front, again, MAKE SURE your shaft will not pull out of the slip spline under full droop. Under full droop you still want at least a couple inches of slip-spline still in there. This setup tends to need a shaft a few inches longer than with a 231. The center of the u-joint in the front output yoke (1310 Spicer CV type) is 5-1/2 inches back of the front of the Klune, where it bolts up to the rear of the trans/Tcase adapter.
In short don't count on the driveshafts fitting as-is, but they just might.
32 spline output kit for the Bronco 20
Data on the Bronco Dana 20 Data Page
How will I hook up my speedo?
Data on the Bronco Dana 20 Data Page