Jeep Wrangler Axle Wrangling - Part 3Posted in How To: Transmission Drivetrain on May 14, 2014
In the world of front axle upgrades, the reverse-rotation (aka “high- pinion”) Dana 60 differential is by far the most coveted. The attraction of any high-pinion front axle is that the pinion gear runs the stronger drive-side ring gear. Compared to a low-pinion Dana 60 front differential that rides on the weaker coast side of the ring gear, the high-pinion 60 is more reliable and robust. Given that the pinion is placed above the centerline of the axletubes, the high-pinion design also aids in protecting the front driveline. Using a 9.75-inch ring gear, the Dana 60 front differential is more than capable of handling high-horsepower demands and extremely large tires.
Last month, we showed you the ins and outs of our East Coast Gear Supply semi-float Dana 60 rear that we placed under our ’97 Jeep Wrangler TJ. In this installment, we are moving up front with an ECGS high-pinion 60 front that will match the durability of what we have out back. As was the case with our rear, we opted for a custom-width East Coast Gear Supply TJ-series Dana 60 axle. While ECGS offers the TJ-series high-pinion front 60 in a bolt-in configuration with stock axle brackets, our V-8-powered Wrangler was far from OE spec.
In fact, our front suspension had a tremendous amount of custom work done to it, so our install was a bit more complex than if we had an off-the-shelf kit. Despite the challenges, our heavily modified Wrangler presented, East Coast Gear Supply was able to complete the install with relative ease at its Raleigh, North Carolina, headquarters. Gathered here are highlights from the front axle build, and the options and upgrades we sprung for.
1. Given that East Coast Gear Supply starts with a used ’99-’04 Ford Super Duty high-pinion Dana 60, it needs to be trimmed down to fit under a Jeep Wrangler TJ. This narrowing process is done by removing the passenger-side C and trimming the axletube down to the desired length. In our case, we opted for a 65-inch WMS. A 63½-inch option is also available.
2. Welding the original C back to the axletube is a slow process that requires pre-heating the knuckle. For this, ECGS uses an oxyacetylene torch and infrared thermometer.
3. To ensure that the axle fits easily under a ’97-’06 Jeep Wrangler TJ application, the axle is placed into a welding jig. Once the caster is set between five and seven degrees, the ¼-inch TJ bracket set is welded to the axle.
4. A unique aspect to the ECGS 60 is the high-clearance lower control arm brackets. These brackets not only raise the lower control arm mounting points, but tie into the front side of the axle mount for increased strength. Since our Jeep was running coilovers, we left off the coil buckets and shock tabs that come standard with the kit.
5. For many at-home axle builders, the differential casting is the largest fabrication hurdle to overcome. Using a specific MIG wire that is engineered for welding to cast, ECGS tackles the welding challenge the best way possible. In addition to welding to the housing, a ½-inch-thick steel truss is bolted to the differential housing. For upper control arm mounts, beefy and rebuildable Johnny Joints are used.
6. To match our rear 60, we went with the brute strength and reliability of a 5.13:1 Yukon gearset. Secured to the 9.75-inch ring gear is a Detroit Locker from Eaton. For our trail rig, the Detroit Locker makes the most sense, as the rugged and simple automatic locker doesn’t require any additional lines or parts.
7. East Coast Gear Supply offers a couple of steering options for its front 60. We opted for the crossover setup—it fits the passenger side with a high-steer arm that bolts to a modified Super Duty knuckle. We used ARP studs in our arm, but Allen-head bolts are standard. New ball joints are also standard with every front 60.
8. While 35-spline 4340 chromoly inner axleshafts come standard with the axle, we upgraded our front with optional 35-spline 4340 chromoly outers as well. To match the strength of our heavyweight shafts, we sourced a set of Yukon 4340 chromoly Superjoints. The Yukon Superjoints have induction-hardened 4140 chromoly caps, along with a 4340 cross. For our tire range of 37 to 40 inches, the shafts and U-joints are nearly bulletproof.
9. You can choose from a few bolt patterns, but we had our unitbearings machined for a 5-on-5½ pattern. Although not serviceable, the load-carrying capacity is more than double that of the Wrangler’s notoriously problematic stock unitbearings.
10. Unlike a conventional unitbearing, these allow the axleshaft to be disengaged via a selectable hub. Since we upgraded from the stock 30-spline outers, we outfitted the unitbearings with Hardcore lockouts from Yukon. Featuring chromoly internals, the 35-spline, low-profile hubs are built with off-road use and abuse in mind. Where a conventional hub would default to an unlock position when broken, the Yukon hubs actually default to the locked position, so you’re not stuck out on the trail.
11. A major braking upgrade comes by way of dual-piston calipers. While the rotors are custom for this application, the calipers and pads are easily sourced F-250 parts.
12. The new length and offset of the differential housing required us to source a new front driveline. We opted to get our custom ’shaft built by Oliver’s Custom Drive Shaft in Winston-Salem, North Carolina. Fitted with a 1310 CV-style yoke at the transfer case and 1310 U-joint at the diff, the heavy-duty shaft provides plenty of range for our 12-inch-travel front suspension.
13. Since we changed over from the Jeep’s 5-on-4½ to a 5-on-5½-inch bolt pattern, we needed new wheels. We’ve had great luck with our 17-inch ATX Slab beadlocks in the past, and the 3½-inch backspacing provided the optimal amount of offset needed to clear our steering and suspension components.