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Transfer Case Low-Gearing Product Guide

Posted in Product Reviews on August 15, 2017
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Photographers: Courtesy of Manufacturers

The transfer case—one of its benefits is that low gear. It’s one of the selling points for the Jeep Wrangler Rubicon. How low you need to go is a talking point around the campfire. And it’s a focal point of what it takes to be capable of crawling a 4x4 over impassable terrain. Sure, big tires and loads of horsepower help get the job done, but ain’t nothing like low gearing to ’wheel with finesse. The aftermarket has some hardcore options in this capacity, from gears and doublers to low-range boxes and all sorts of innovation in between. Here’s a sampling of what’s available.

Magnum Gearbox from Offroad Design

What: The Magnum underdrive is a planetary gearbox, and finds its home between the transmission and NP205 T-case. By adding the Magnum, think of it as having four ranges: the NP205’s stock 1:1 high range and 2:1 low range and two more low ranges—the Magnum in low range coupled with the NP205 in high range for 2.72:1, and 5.33:1 when both are in low range.
Some tech: The company utilizes a one-piece input for connecting to the NP205, and it’s big—a diameter of 1 3/4-inch—plus the underdrive is short and lightweight.
Helpful to know: “We can build entire systems for you with the NP205 and Magnum shipped to you ready to install with common upgrades like HD yokes and bearing retainers, new shift rails, and HD output shafts.”
Price: You’re looking at $1,990
How to get: Offroad Design, offroaddesign.com

Trail-Gear Trail-Creeper

What: The name kind of says it all for what you’re gonna get, but just in case…it’s a T-case reduction gear kit. This equates to a 4.70:1 low range ratio for the ’79-’95 Toyota pickup and 4Runner T-case. You can buy the Trail-Creeper gears as 21 or 23 spline, and the kit has replacement gears, gaskets, and seals. The gearset will reduce the stock low range from 2.28:1.
Some tech: The company said it chose Japanese alloy SCM415 for its strength and wear-resistance, and because it’s a material that also remains strong under high-temp usage.
Helpful to know: “V-6 applications require the transfer case be replaced with a four-cylinder gear-drive unit and V-6 adapter plate. Speedo cable, floorboard, driveshaft, and crossmember changes may also be required.”
Price: $549
How to get: Trail-Gear, trail-gear.com

NorthWest FabWorks Blackbox Series

What: The Blackbox Series is a line of shiftable underdrive gearboxes—you’ll have a gear-reduction box that can take you from 1:1 to 2.72:1 low range, for three low ranges (with your current T-case). It fits many vehicles, including Jeep, Ford, GM, Toyota, and Dodge/Ram, but also aftermarket cases, such as the Hero and Atlas II.
Some tech: The company says the planetary gearbox has an 80mm roller bearing support at the input and output of the 8620 mainshaft. It also has an adjustable shifter assembly, an optional cable shifter, billet input retainers, and 360-degree clocking for rotating the T-case 360 degrees.
Helpful to know: “Due to the unique design, the Blackbox can often adapt transmission/transfer case combos without any additional parts.”
Price: Ranges from $729-$1,749
How to get: NorthWest FabWorks, northwestfab.com

Novak 300RX

What: The 300RX from Novak works with all ’80-’86 D300s (this includes the ’80 short and IH). This heavy-duty Dana 300 output—as short as you’ll likely find—equates to 4.625 inches, which is 1.8 inches shorter than the long-output version and .75 inch shorter than the short-output version, Novak said, regarding the measurements taken from the rear face of the T-case to the center of the U-joint.
Some tech: There’s a 32-spline alloy shaft, two tapered roller bearings, a grooved input shaft pilot bearing, and a tailhousing cast from 356 aluminum, then strengthened.
Helpful to know: “It works with all known gearsets and adaptations in standard or flipped configuration with dual breather ports to accommodate either orientation. Because of the extreme short length, it will only accommodate an electronic speed signal. The 3-pulse (stock later-model Jeep) or 40-pulse (standard late GM) reluctor options are available. If no sensor is ordered, that port will come with a plug where the sensor would go.”
Price: MSRP is $619
How to get: Novak Conversions, novak-adapt.com

Marlin Crawler Dual Transfer Case

What: Know that if Mount Rushmore got redone as “Mount Slowmore,” this would be one of the founding faces in that reimagined carving. The TacoBox Supreme is for the Toyota Tacoma, 4Runner, FJ Cruiser, and T100, and turns the transfer case into a four-speed, with up to 28 different speeds (as in, 24 forward gears, 4 reverse). Selectable gear ratios are 1.00:1, 2.57:1, 4.70:1, and 12.08:1.
Some tech: Japanese-made chromoly gearing, 32-ball-count double roll main bearing.
Helpful to know: “Installing a dual transfer case into a four-cylinder-equipped truck requires moving your existing T-case back approximately 6 1/2 inches. The additional crawl box is installed between the transmission and T-case. All four-cylinder gear-driven T-cases are 21 spline except for the ’86-’87 turbo, which is 23 spline. 2.28:1 or 4.70:1 gears can be used in any combination in the two T-cases. The most common choice is one set of 2.28:1 gears and one set of 4.70:1 gears, known as a Dual Ultimate Crawler.”
Price: MSRP of $2,199
How to get: Marlin Crawler Inc., marlincrawler.com

Low-Range Gearset for Dana 20

What: Summit Racing’s got what you need if you’re trying to slow your ’63-’79 Jeep CJ, Jeepster, pickup, or Wagoneer. Ditto a ’72-’79 IH Scout. This Advanced Adapters low-range gearset is a five-gear kit that knocks out the factory 2.03:1 low for 3.15:1 gearing.
Some tech: There are kits for either the Dana 18 or Dana 20 transfer cases, and include all the hardware and gaskets you need.
Helpful to know: “A slight amount of internal case grinding is necessary.”
Price: Approximately $1,200
How to get: Summit Racing Equipment, summitracing.com

LoMax 4-to-1 Reduction Gearset from JB Conversions

What: The LoMax from JB Conversions is for the Jeep Dana 300 T-case with a 4:1 reduction in low range. This “five-gear set” features notable tooth volute shapes and gear-hub beefiness.
Some tech: The LoMax features one-piece construction, and there are two 27-tooth gears and two 18-tooth gears, plus an idler gear and custom shift rail included in the kit.
Helpful to know: “The LoMax gears are compatible with both the long- and short-tail versions of the Dana 300. Although not required, it is highly recommended that a complete rebuild accompany the installation of the LoMax gears. Supplemental rebuild kits are available from JB Conversions.”
Price: Starts at around $1,000
How to get: JB Conversions Inc., jbconversions.com

Advance Adapters Atlas

What: The Atlas has been around since 1996, and both two- and four-speed are available (Atlas 2 and Atlas 4, respectively). There’s also a race version with extra beef. You can customize your Atlas based on yoke, shifter, tailhousing, and other needs.
Some tech: Gear-driven T-case. There’s a new internal oil pump for flat-towing your rig while still oiling the gears, plus an optional parking brake. And you have multiple choices in gear ratios for two- and four-speeds. Low-range ratios run from 1.5-5.0—multiplied in the Atlas 4.
Helpful to know: “The installation of an Atlas four-speed should be nearly the same as the standard Atlas two-speed. The Atlas four-speed is just a bit longer.”
Price: Varies by app since they’re custom built. For example, the four-speed for the Jeep JK could cost you around $3,500.
How to get: Advance Adapters, advanceadapters.com

TeraFlex Two-Wheel-Drive Low-Range Kit

What: The 241OR 2Low 2WD Low Range Shift Sector Kit is for the Jeep Wrangler Rubicon and will up (er, down) your low-range shift pattern to include a two-wheel-drive low range.
Some tech: Your new shift pattern? 2-Hi, 4-Hi, Neutral, 2-Lo, and 4-Lo. A bonus should be better turning capabilities for you on narrow switchbacks. Another bonus could be steering bind going away.
Helpful to know: “The 2Low retains the use of all factory low-range options, such as ESP disabling, electronic sway bar disconnect, and locker engage and disengagement.”
Price: About $272
How to get: TeraFlex, teraflex.com

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