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RockJock Dana-60 Rear Axle - 60 Grand

Jeep Grand Cherokee Zj
Kevin Blumer | Writer
Posted August 9, 2013

Serious Axle Options for the ZJ

If you're building a ZJ Grand Cherokee for the trail, chances are you've considered upgrading or upsizing your axles. Yes, it's possible to put better guts inside the stock housing, but then you've still got a stock housing: weak! A close look at a stock ZJ Dana 35 or aluminum centersection Dana 44 rear axle reveals multiple brackets. To successfully swap an axle, these brackets must be transferred onto the new housing. Of course, that's easier said than done.

Currie Enterprises speaks the language of all things axle. Transferring brackets is an everyday exercise for the Currie crew, and they've got the shop fixtures and machines to make sure the brackets are right where they need to be on the new housing.

Options for ditching your stock Dana rear axle include an upgraded Dana 44 with an iron centersection, Ford 9-inch, and RockJock Dana 60. Any one of these axles offers strength well beyond the stock rearend. Abusive drivers running big tires should skip the others and go straight for the 60. Follow along as a ZJ gets the 60-grand rear axle treatment.

Step By Step

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  • The donor axle awaits its fate.

  • The rotors and calipers will be reused, which makes for readily available replacement parts. This ZJ’s build plans included a swap to a new wheel bolt pattern, so the rotors will have the new pattern drilled in.

  • Before the torching begins, the donor axle’s differential, axleshafts, and gear oil are removed. The housing is then cleaned.

  • A cutting torch easily slices through the axle tubes. In this case, it was more important to preserve bracket material than to preserve the axle tubes, so the tubes got sliced into. After this exercise, the housing is junk, but the brackets are ready for a new life.

  • A cutting torch easily slices through the axle tubes. In this case, it was more important to preserve bracket material than to preserve the axle tubes, so the tubes got sliced into. After this exercise, the housing is junk, but the brackets are ready for a new life.

  • The brackets are cleaned and ready to be fitted to the RockJock 60.

  • RockJock 60 housings consist of a cast centersection and a pair of pressed-in axle tubes. Thermodynamics come into play here. The centersection is heated up in an oven, which expands the axle tube holes.

  • The axle tubes are machined for an ideal fit inside the centersection. With the axle tubes cool, they’re easily brought home inside the heated centersection. The ends of the tubes are coated with sealant, and then the tube is fitted into the centersection using a BFH, or Big Freakin’ Hammer. A plate is placed over the end of the axle tube so that the BFH does not hammer directly on the tube. When the centersection cools down, it contracts around the axle tubes and creates a permanent bond to establish a second line of defense. There are also setscrews between the centersection and the axle tubes.

  • Axle bracket fixtures don’t have to be pretty, but they’ve absolutely got to be accurate. The fixture is leveled before the vise gets clamped.

  • The pinion is set to 90 degrees, and the housing is centered in the fixture. Next, the housing is clamped in the fixture.

  • A reference housing is brought in. Like the new housing, the pinion is set at 90 degrees and the housing is secured in place. Now the measuring, fitting, and tack welding can begin.

  • The boltholes don’t line up just yet, so there’s some fitting needed.

  • The brackets are fitted by removing a little material at a time and checking the fit frequently. Here, an area is marked that needs to be trimmed.

  • Trimming is accomplished using grinders and a plasma cutter. The plasma cutter takes off the major portions and then the grinders are used to sneak up on the desired final dimension.

  • The bolt fits smoothly, so these brackets are ready to be tack welded.

  • The coil spring seats don’t have any boltholes for reference, so correct position is established by measuring the angle and the lateral position relative to the end of the axlehousing.

  • At this point, most of the brackets are tacked into place. Sway bar link brackets still need to be added, but they’ll get in the way while the housing ends are welded. So, the housing ends are next.

  • A rotating weld positioner turns the housing and makes welding easier and therefore more consistent.

  • The weld beads look great! More significantly, they’re strong.

  • The weld beads look great! More significantly, they’re strong.

  • The sway bar end link brackets were added next, and then the housing was cleaned again. This time, a cleaning machine was used that creates a beautiful finish. This looks like silver paint, but it’s actually bare metal. The upper link brackets were only tacked into place because this axle will be used with a Clayton Off Road four-link kit, which uses non-factory upper link mounts. Even though the upper link brackets will be coming back off, we still wanted to show you a complete set of ZJ axle brackets in their correct positions.

  • Just as with the brackets, there’s a fixture for drilling wheel bolt patterns.

  • A Detroit Locker is an excellent no-fuss choice for off-road traction. Superior gears and an installation kit completed the needed differential parts.

  • New backing plates are part of the package, and they’ll join the reused brake rotors and calipers.

  • The differential is now correctly set up and at home inside the RockJock 60.

  • Wheel studs were pressed into the axle flanges after which bearings were pressed onto the axleshafts. Backing plates in place, the shaft assemblies were slid into place and bolted home in the housing.

  • The RockJock diff cover is made from heavy plate and it’s the perfect match for the rest of the RockJock 60’s bombproof construction.

  • One RockJock 60, adapted to a ZJ and ready to go.

Sources

Currie Enterprises
714-528-6957
www.currieenterprises.com
Superior Axle & Gear
Rancho Cucamonga, CA 91730
888-845-0470
www.superioraxlegear.com
Eaton Detroit Locker
www.eaton.com

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