Made-to-OrderSwapping a Stock Dana 35 for a Currie 9-inch
Any Jeep owner who engages in serious off-roading will likely snap a rear end; it's just an accepted risk in pursuit of the adventure. Swapping to a stronger rear end comes at one of two times in a vehicle's lifetime: when there's breakage or when the owner has the foresight to prevent breakage.
Currie Enterprises has a solution for both. A Currie-Built Rearend (CBR) is a premium kit that includes a bolt-in axle housing with vehicle-specific heavy-duty suspension brackets, a properly prepared third-member with the desired gear ratio, high-strength axles, choice of drum- or disc-brake assemblies and all necessary hardware. Based on the Ford 9-inch design, a CBR is built with all-new components designed for strength. None of the parts are rebuilt or reconditioned used pieces from a salvage yard.
A CBR might seem like an expensive solution for a busted ring or spider gear in a stock unit. Those problems can be repaired at a reasonable cost. But can you afford to make the same repair again if you keep going off-road or if you want to attempt tougher trails? Also, just about any one with entry-level mechanical skills and basic hand tools can perform this swap. A broken rear differential should be repaired by a trained technician, so labor costs enter into the bottom line.
When swapping to a stronger rear end, most Jeep owners won't stop there. Stronger links, taller springs, appropriate shock absorbers and beefier brakes are usually considered. With so many choices, Currie builds the rear end to suit those needs. If a different pinion angle is required, then the welding jig is adjusted. Lower gears are needed to support larger tires, just let Currie know the ratio needed; or tell Currie the tire size and tech support will recommend a ratio.
The beauty of this system is how easily it can be upgraded, especially when dealing with brakes. Currie worked with three major brake suppliers to standardize many of the dimensions. Choice of axles or wheel-bolt pattern size won't interfere with installing either Currie drum brakes, Currie Explorer disc brakes or disc brakes from Baer, Stainless Steel or Wilwood. With a removable third-member, gear ratios and locking devices can be swapped with ease.
To illustrate just how easy the CBR system is assembled and installed, we followed the procedure on a stock TJ. The swap took less than five hours with an experienced mechanic, Tony Sato, handling the tools. But owners with average wrench skills and a friend or two can easily finish the job in a day in a driveway. Access to power tools and a lift will reduce the time even more.
Necessary tools include basic wrenches and sockets in both standard and metric. Also, hammers, pry bars, a floor jack, jack stands and a torque wrench will be needed. An impact wrench speeds up disassembly but isn't necessary. Other necessities include RTV silicone, anti-seize lube and spray lubricant like WD40. Small boxes or trays to keep track of hardware will come in handy as will shop rags and a drain pan to collect any leaking tranny or brake fluid.
The vehicle should be parked on a level surface with a chock or block placed under the front wheels. Once the vehicle is lifted and supported with jack stands, the rearend is supported with a floor jack. Removing the stock rearend is a routine operation. Currie suggests unbolting the shocks at the lower mount, then loosening and removing the nuts — but not the bolts — on the upper and lower links. Once all the brake lines are disconnected, the link bolts can be removed and rearend lowered to remove the coil springs. Once the Panhard bar is disconnected, the rearend can be removed from the vehicle.
When inspecting the CBR parts, customers will notice a few unique features about the kit. All the joints on the axle housing are MIG welded and the housing ends have the larger Torino-style bolt pattern. All the brackets are laser cut and MIG welded to the housing. On the TJ, the Panhard or trac-bar mount has multiple holes to accommodate different lift kits. The shock mounts are rolled back enough to allow more clearance between the shock absorber and spring pad. Also, the spring indexing hub is already drilled and threaded for aftermarket bump stops. Finally, the 31-spline, 1541 forged axles are double drilled for both 5-on-4.5 and 5 on 5.5 bolt circles. The third-member assembly featured a Detroit Locker with 4.57:1 gears.
For this install, the Currie 11-inch disc brake kit based on the Ford Explorer design was used. Currie also offers 11x2.25 drum brakes and a choice of popular high-performance aftermarket disc-brake kits with up to 14-inch diameter rotors and 4-piston calipers.
Hard brake lines must be installed, but there are no provisions to mount the lines on the rearend. Currie can supply steel lines with all the necessary fittings.Currie also has flex-hose kits to the calipers than include weld-on bulkhead fittings. These fittings were already in place on the axle we installed, but the fittings can either be tack-welded or secured with a hose clamp. We did bend new hard lines from the bulkhead fittings to the stock junction block, which was adapted to the Currie rearend at the vent-tube provision by drilling and tapping the hole. A customer can also mount the stock junction block with a hose clamp. If drum brakes are used, then the stock E-brake cables can be retained. When switching to disc brakes, the cable must be changed. Currie can supply all the necessary parts.
Assembly of the rearend is straightforward. A silicone seal helps secure the third-member to the axle housing. The axles come in two different lengths: the longer one is for the passenger side and the shorter one goes on the driver's side. Once the Currie rearend is installed, the brake lines must be connected and the brakes bled. Currie recommends a 10-minute test run at idle while the rear wheels are lifted and the transmission is in gear. Allow the rearend to completely cool before taking the first test drive. For the first 100 miles, Currie suggests short drives of no more than 10 miles to keep the pinion bearings from building too much heat.