1997 Jeep Wrangler - Mayhem To Moab: Part 4
Rock Stopping Gears & Axles
Our cute little TJ is all grown up, what with 37-inch Pit Bulls and a flexy low-slung suspension, but that is just part of the recipe. We wanted to have a Jeep we could bounce over rocks and not worry about the axles, while also having the gearing to make up for our measly little four-cylinder engine.
Don’t get us wrong. We’re not building a Southern-style Day-Glo Orange rock-bouncing buggy. We just want a tough little Jeep to run trails with in Moab, one that is built enough that we can keep up with some of those original Southern rock bouncers like Fred Perry of the Clemson 4-Wheel center, and Chris Durham. In fact, it’s these two guys who got us excited to build a Jeep. Wranglers are so common that you’d think we would bypass one for something more unique and oddball, but it’s pretty hard to argue with a Jeep Wrangler as a build platform. Yes, we may end up swapping all the drivetrain over the life of the Jeep we’ve affectionately named Tube-Sock, but that’s nothing new—it’s just what Jeepers do.
Jeep TJ Wranglers come stock with a Dana 30 front axle and Dana 35 rear. Not a bad combo with stock tires, but throw big tires, even bigger rocks, and a big right boot on the throttle peddle and you’ll be wrenching on busted axle parts. We’re not going to tell you that these stock axles are junk, but they are not going to work for what we have in mind for the Jeep. Step one, delete the factory axles.
There are a ton of axle options for a Jeep, and just about every option has been tried, twice. For Tube-Sock we wanted new axles for ease of assembly, installation, and reliability. Plus, we were on a tight timeline to get this Jeep built so our first stop was Currie Enterprise where a pair of ARB Air Lockers and 5.38 high-pinion gears from Motive Gear were waiting for us.
Tube-Sock has a 2.5L four-cylinder engine and 37-inch tires, so although we wanted strong axles we didn’t need anything outrageous. Currie offers high-pinion Rock Jock axles in Dana 60 and 44 sizes as well as a new monster 70. We had first considered one of the Currie Fabricated 9-inch rear axles but determined that it was going to have quite the low pinion for a rockcrawler. In the end we decided on the new Jeep JK–style front Rock Jock 44 and a rear Rock Jock 60, as both high-pinion axles will help with driveline angles and keep the driveshafts above rocks.
Our front axle was built 65 inches wide, very similar to Jeep JK width but with Jeep TJ brackets. The completely new axlehousing is built to spec for each and every Currie customer with a new cast centersection and new axletubes.
We decided on Synergy ball joints and Reid Jeep JK knuckles for our front axle. We were hoping to use as many off-the-shelf parts on the build as possible, and this allowed us to use a Currie tie rod designed for a Jeep JK.
We also wanted to run a 5-on-51⁄2-inch bolt pattern wheel, but the Jeep JK axles usually have 5-on-5-inch pattern. The solution is a unit bearing from Mopar designed for the military jeep J8 axles (PN 56052930AB), which bolts right to our Reid JK knuckles. However, we had to slightly machine the rotors to fit over the J8 Hub. We are investigating getting the entire Jeep J8 unit bearing, brake rotors, calipers, and caliper stands to eliminate machining and allow any JK axle to be changed to 5-on-51⁄2.
Into that front axle we stuffed a set of custom Currie chromoly axleshafts with JK J-joints from CTM racing. CTM makes tough joints, and we like strong parts so that we can drive like an idiot off-road. The beef of the CTM joint is obvious compared to a stock JK joint, and the CTM joints are made of heat-treated 300m material.
Even though we stuffed 5.38 gears in the axles, we decided that Tube-Sock could use even more low-range gearing for Moab rocks. Our friend Tony works on Jeeps a fair bit, and he came over to help swap in a TeraFlex Manufacturing 4-to-1 low range kit in our 231 transfer case. To learn more about these low-range conversions, check out Jim Brightly’s “Gearing Down” article in our June ’14 issue.