Done In A Day: Jeep Steering Box SwapPosted in How To: Transmission Drivetrain on August 7, 2018
You might be at that point in the development of your Jeep build at which a steering upgrade has become the obvious next step. The suspension system that led to the bigger wheels and tires has also led to much more effort needed to get those big meats pointed in the right direction when the trails you’re exploring begin to get into the “black diamond” category. There are a number of options ranging from completely gutting and replacing the steering system with a full hydraulic setup to bracing the factory box so it can handle the twisting and tweaking a bit better.
Of the broad range of options, we’re going to shoot for something in the middle and explore the simple yet effective method of upgrading the steering system on a Jeep Wrangler JK¬–swapping out the factory steering box with a beefed up aftermarket version. It’s a quick and easy job that you can have done in a day in your garage, but the lasting result will be a much better driving experience on- or off-road.
The Big Bore XD (P/N SG688) from Performance Steering Components (PSC) has applications for ’07 to ’18 Jeep JK Wranglers, and that’s what we’re going to focus on here. However, the company also makes a Big Bore XD unit for the TJ/LJ, XJ, and CJ back to ’80. Claimed to be the most powerful (producing 35 percent more turning force than the factory part) and strongest replacement Jeep JK steering box on the market, it is highly recommended for any JK running large tires or a front locker.
Much of the Big Bore XD’s claim to fame is due to the larger piston (80mm as opposed to the factory 70mm); the same as found in late-model Ram 2500/3500 diesel trucks. The gearbox’s sector shaft is also fatter (45mm compared to the factory 35mm). The case (15 pounds heavier than factory) is much sturdier than stock, and all the mounting areas have been beefed up too.
A couple of notes before we go any further: The larger size of the Big Bore XD can create a fitment problem with some aftermarket track bars. It may also have clearance issues that need to be addressed with certain V-8 swaps. Check with PSC about your specific application.
The Big Bore XD steering box is made to operate at pressures as high as 1,800 psi, and PSC recommends the use of its high flow/pressure pump kit (that runs at 1,800 psi and produces 50 percent more volume per revolution than the factory pump) with the Big Bore XD box. However, it is not absolutely necessary, as the factory pump puts out 1,500 psi and will operate the Big Bore XD just fine, just not at the gearbox’s full potential.
The 2012 Jeep Wrangler JKU Rubicon used for this steering gearbox swap rides on 37-inch tires and was built to be a multi-purpose trail runner and off-road camping vehicle, not a hardcore rock crawler, so we determined the Big Bore XD gearbox alone was enough to make a noticeable difference in the performance of this trail runner/daily driver. We now have more than 5,000 miles on the unit and it has solved the “steering moan blues” and instantly brought the steering feel back to factory levels. On the road, the steering is light and responsive, unimpeded by the larger tires. On the trail, the steering remains light to the touch and it takes less fighting with your steering wheel when going over the rough stuff. We have been rewarded with greatly improved steering feel and muscle with the installation of this PSC Big Bore XD steering gearbox.