If you've driven or even ridden in over-the-road trucks (18-wheelers), then you probably won't be surprised that Don Scoggins has finally created the Brabnod Mountain Gear. You may even be kicking yourself for not doing it yourself. Scoggins adapted big-truck auxiliary-transmission technology to give your fullsize or downsize 4x4 a four-speed intermediate gearbox that more than triples your transfer case low range and tacks on a 21 percent overdrive. The Brabnod Mountain Gear mounts between your tranny (on most popular 4x4 autos or manuals) and your transfer case. So its 3.258:1 deep Underdrive, 2.575:1 Second Under, 1:1 Direct, and .79:1 Overdrive work in both two- and four-wheel drive, and both low and high range. Not only that, but the Mountain Gear is a complete auxiliary tranny, so you can split each of the regular tranny gears too. Whether you're four-wheeling, towing, or just climbing a steep grade, you can select that perfect half-gear to keep your engine in its powerband. The Brabnod Mountain Gear box has no shift lever. Scoggins adapted a push-button air-shift system from big rigs too. The price may sound steep at about $3,500, but that's comparable to many double-transfer-case setups and offers much more. Let's take a closer look at this gearhead's dreambox and its installation in an '87 Ford Ranger. Scoggins' 15 years of experience with big-rig trannies led him to choose Eaton gears designed for 18-wheeled diesels that generate 1,600 lb-ft of torque and carry loads up to 80,000 pounds. He made the Mountain Gear compact by designing its five gearshafts to share just two common centerlines instead of the three or more centerlines found in big-rig trannies.Scoggins' 15 years of experience with big-rig trannies led him to choose Eaton gears desig The massive Eaton gears are 1 1/4 inches thick (about the size of NP205 transfer-case gears). According to Scoggins, the square-cut teeth are used in 18-wheeler trannies because they stay engaged under intense torque loads better than helical-cut gears. And he also utilizes big-truck sliding clutches instead of smaller, weaker brass synchronizers found in light-truck trannies.The massive Eaton gears are 1 1/4 inches thick (about the size of NP205 transfer-case gear The Mountain Gear input shaft (top in box) drives the Low and Direct gears. The main shaft (center) interlinks to produce Direct and Underdrives. The gearset at right links the input with the output shaft. The gearset at left is for Direct and Overdrive. The shaft in the foreground is the output shaft and connects to the transfer case.The Mountain Gear input shaft (top in box) drives the Low and Direct gears. The main shaft To make the Eaton gears work in the compact unit, Scoggins designed numerous unique components such as this shaft and retainer. All these parts are machined from 4130 chrome-moly steel and then tempered.To make the Eaton gears work in the compact unit, Scoggins designed numerous unique compon Air-activated plungers move two shift rails that, in turn, cause the shift forks to engage or release the sliding clutches. Brabnod Machine does not supply a compressor with the Mountain Gear, but you can use an ARB or other compressor, or a converted air-conditioning compressor. Brabnod's instructions include guidelines for choosing the right compressor and plumbing the air lines.Air-activated plungers move two shift rails that, in turn, cause the shift forks to engage Brabnod offers adapters to mate the Mountain Gear to a range of popular 4x4 trannies and to bolt up a range of transfer cases behind it. The '87 Ford Ranger shown here has a 3-inch body lift, a 302 V-8, an NP435 four-speed manual tranny, and an NP205 transfer case. Most installations require some modifications to the floorpan. Here, the empty case must be bolted to the NP435 before the gears can be installed according to the instructions.Brabnod offers adapters to mate the Mountain Gear to a range of popular 4x4 trannies and t Another big-rig influence, this Eaton shift knob replaces the regular tranny knob and contains the air fittings and buttons needed to shift the Mountain Gear. One button operates Direct (1:1) and Overdrive; the other selects the Underdrives. You can shift while the 4x4 is moving (but slowly for Underdrives, especially if the transfer case is in low range too). It takes a bit of practice to rock the accelerator and hit the button in sync for smooth shifts, but the air shift is fast and engagement is sure.Another big-rig influence, this Eaton shift knob replaces the regular tranny knob and cont For a good time, crunch these numbers: Multiply the NP435's 6.7:1 Low, the Mountain Gear's 3.26:1 deep Under, the NP205's 2:1 Low range, and the Ranger's 3.54:1 axle gears. That's a cliff-climbing 151.10:1 final drive ratio with highway gears in the axles! Brabnod does not supply crossmembers because of application variations. The Mountain Gear's 14-inch length is just 5 inches longer than the stock NP435-to-NP205 adapter, but that's enough to require new front and rear driveshafts.For a good time, crunch these numbers: Multiply the NP435's 6.7:1 Low, the Mountain Gear's The Mountain Gear is the heavy hitter, but the company also offers smaller, simpler units such as this 3.23:1 Underdrive/ Direct drive. The lighter-duty box contains a planetary gear setup and uses a manual shifter. It fits between GM TH350, TH400 or TH700-R4 automatic trannies and NP205s, 208s, and 241s. Adapters are also available to mate it to Toyota transfer cases.The Mountain Gear is the heavy hitter, but the company also offers smaller, simpler units Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!
