We begin with the front axle of a '97 TJ first featured in the May '08 issue. Sporting a 4-inch JKS J-Spec suspension system, our donor Jeep was ready to step up to 35-inch-tall tires. We feared the increase in tire diameter would result in broken parts on the trail. A little investigation revealed several new products we've never tested before.
TJ owners have always benefitted from legendary capability in the dirt. No other vehicle can quite match the sure-footed '97-'06 Wrangler's trail prowess in stock form. Well, that is until the new JK recently hit the scene. But still, when it comes to an affordable 4x4, a TJ is hard to beat. As such, people love to tinker with them. Bolt-on products such as flexy suspension and body parts that allow fitment of larger tires make it easy to outgrow the factory Dana axles.
Conventional wisdom tells us that stock TJ axles will survive just fine with up to 33-inch-tall tires and smart driving. It's the 35-inch-and-up range where the factory underpinnings of a TJ start to really show signs of weakness. So we thought we'd examine the strength threshold and showcase a group of new parts that should collectively increase the durability of the Dana 30 front and 35 rear axles. This two-part series will shed some light on what's required to gain additional strength without swapping in a portly pair of Dana 60s. Follow along now as the good folks of DC Customs of Ukiah, California, push the envelope to make a Dana 30 survive against 35-inch tires.
In stock form the Dana 30 doesn't have much to offer those of us who want to run larger tires. However, unpopularity makes them cheap and easy to find in wrecking yards. Thanks to a healthy production run, they are quite easy to get parts for too. Today the aftermarket has tons of upgrades that improve strength. You can find these axles in Cherokees (XJ) and Wranglers (YJ), as well as the previously mentioned TJ. The best version to start with is the unit found under the '91-'01 Jeep XJs. This particular model offers obvious benefits thanks to its high-pinion design and are inarguably the stoutest of Dana 30s built. These axles use a live spindle design which features sealed wheel bearings and no locking hubs. Try to avoid the pre-'91 units that came with a vacuum-operated CAD (axle disconnect), which split the passenger-side inner axleshaft into two pieces with a coupling in between. It is known that the weakest part of the Dana 30 is the 5-297 Spicer axle U-joints.
Reid Racing now offers a Dana 30 conversion knuckle that allows users to run Dana 44 outers on the model 30 front housing. This conversion eliminates the problematic unit bearings and allows use of stronger tapered roller bearings. This is a good thing for those who want the option of locking hubs. These knuckles are cast from high-strength ductile iron and feature extra material and ribbing where it counts. Flat tops are machined and drilled to allow fitment of high-steer arms, and cast-in dual steering stops eliminate bent stop bolts that can lead to U-joint and axle failures. High-steer arms are available for these stout knuckles from PartsMike.com, a manufacturer who specializes in Jeep upgrades and modifications.
Stage 8 manufactures a vastly improved locking spindle-nut system for Dana 44 and 60 outers. We like this system because they install easily without any specialized tools and they can withstand extremely high reverse torque loads while preserving targeted bearing preload. The secret is in the 1/2-degree clocking ring, which allows virtually infinite preload adjustment. In other words, with these installed you never have to over- or under-torque the locking nut to engage the locking mechanism. This system will work on all Dana 44/60 spindles with a keyway and is guaranteed not to fail.
The heart of our Dana 30 build is the awesome Eaton selectable E-Locker. This differential was built with wheelers in mind. It features a strong four-pinion design and allows users to convert to the stronger 31-spline axleshafts. Operated by electrical current rather than compressed air or cables, this differential offers further simplicity over other selectable lockers available today. We like the fact that it engages with the push of a button and takes less than a second to actuate. These differentials are standard equipment on Hummer H2 and H3 currently, which leads us to believe they have a proven track record for dependability.
Solid Axle hooked us up with one of its all-inclusive frontend kits. The package includes all the parts and pieces necessary to convert a Dana 44 front axle to the stronger 5-on-5.5 lug pattern. The Reid Racing knuckles mentioned earlier allowed us to convert our Dana 30 to the stronger Dana 44 style outers shown here. Solid Axle includes two forged hubs, two forged front spindles, two front caliper brackets, two rotors, two new loaded brake calipers, two stub shafts, and all necessary fasteners and hardware.
Superior Axle took care of our gearing needs by providing a set of 4.88:1 gears and a master install kit. We immediately sent the ring-and-pinion out to Cryo Science of Oceanside, California, to have the gears cryogenically treated. This process strengthens the metal by eliminating areas in the grain structure where stress typically causes fractions. Essentially this process doubles the strength of the material without physically changing the parts dimensionally. It took roughly a week start to finish to have this process completed.
We hit up Blue Torch Fab Works for one of its smooth-looking Kryptonite differential covers. These covers are fabricated from 1/4-inch-thick steel plate and feature a 3/8-inch-thick steel ring for the bolting flange. Built to resist "peel up" and damage that would otherwise cause stock covers to leak, this unit is perfect for rockcrawling rigs like the one we're building. To seal this awesome cover we scored a Lube Locker gasket. Lube Lockers are the most advanced differential gaskets manufactured today. Each gasket features rubber-coated, steel-core construction. What we like about these gaskets is the orange elastomer beading around the perimeter and surrounding each bolt hole. This arrangement virtually eliminates any possibility of a leaky differential, even if the cover smacks a rock and shifts slightly.
Superior Axle also hooked us up with a set of high-strength 30-spline Evolution axleshafts for the project. These shafts feature a dual heat-treatment process to improve durability. These shafts accept full circle clips and each has rolled splines that result in a 35-percent strength increase over traditional cut splines. The dark black color relates to the corrosion-resistant DuraCoat finish that prevents these shafts from ever looking like the original shown here. Another cool aspect of these shafts is the fact that Superior engineers them with equalizing-diameter profiles which allows the short side axle to have similar ductility as the long side. This means each side is equal in torsional strength. Therefore you shouldn't snap the short side just because it doesn't twist as much as the long side.
We opted to use genuine Amsoil synthetic gear lube because Amsoil claims its lubricants maintain viscosity better than other oils available today. We figure it was worth a try, seeing as this rig will likely see a lot of highway miles going forward. The proprietary additives in this lube are said to form an iron-sulfide barrier coating on gear surfaces, providing the superior defense against wear, pitting, and scoring. We'll update you on our results later towards the end of '09 and let you know what we think.
This is the completed Dana 30/44 hybrid axle just prior to installation in the TJ. Look for Part 2 of this project in the coming months. At that time we will address and upgrade the rear Dana 35 axle found under this Jeep with a similar build strategy, while showcasing some of the latest product offerings.
