Jeep Wrangler JK PSC Hydro-assist steering upgrade

Jeep Steering Boost

Bruce W. SmithPhotographer, Writer

A few years ago, if your Wrangler was running on 35s, you were playing in the big league. Now 37-inch rubber has almost become the norm on the street, while the serious trail-running crowd is spinning 40s. Changes in gearing can give your rig the performance to cover some pretty serious terrain on those big tires. However, there’s another area JK owners soon discover that also needs addressing when rolling on rubber that’s hip-high: the power steering. The bigger the tires, the more steering muscle it takes to turn them; especially when the going gets slow, the terrain gets steep and boulder strewn, or the mud is thick and the ruts deep.

Turning Big Rubber
To offset the strain big tires bring, Texas-based Performance Steering Components (PSC) has used its vast motorsports expertise to design hydraulic steering-assist kits specifically for JKs running big tires. The hydro-assist system is said to give a 50 percent boost in turning muscle to the stock Jeep system, all without changing the steering effort and feel from the driver’s seat. PSC’s hydraulic steering-assist kits are well designed, and have all the parts needed for a clean, custom-looking installation. For the most part it’s a bolt-in kit, with the only welding needed on the tabs for the track bar bracket so the hydraulic cylinder’s ram can be attached to the drag link.

Jeff Allen, one of the co-owners of PSC, says their kits target three key components in the later-model stock JK steering system for modification or replacement: the steering gearbox, the power steering pump, and the PS reservoir.

PSC's new steering gearbox is a modified unit that provides two extra pressure ports to allow use of a steering cylinder on the front axle. The steering gear modifications include replacement of the spool valve housing and the modifications of the spool valve to accelerate the fluid through the gear as fast and unrestricted as possible. Jeff told us, “These modifications are critical to the overall speed and operating temperature of the system.”

That’s also why PSC replaces the OE power steering pump with a new one that increases the amount of fluid driven to the gearbox by 50 percent per revolution. This is the key to producing more fluid power at lower engine rpm, which is critical when wheeling in demanding conditions. Jeff says the system pressure is also increased from the stock pump’s 1,500 psi to 1,750-1,800 psi, again to facilitate the rapid delivery of fluid to the PSC steering-assist cylinder and the muscle needed to handle big tires.

Handling Heat & Aeration
Increasing fluid pressures and volume creates more heat in cylinder-assist steering systems, which is why PSC highly recommends the use of both a cooler and quality power steering fluid. “We recommend Swepco 715 in our systems because we think it’s the best power steering fluid on the market,” says Jeff. “Swepco has a anti-foaming agent that actually improves as more heat is created in the system.”

Keeping the power steering fluid from aerating aids the pump in the fluid delivery to the gearbox and on to the hydraulic cylinder, which is why PSC includes a custom aluminum P/S reservoir with internal filter that replaces the plastic OEM reservoir. The PSC reservoir holds more fluid, and its design provides special baffling to prevent aeration, which in turn prevents P/S pump cavitation.

PSC has also found that in the 2012-and-newer JKs, the pressure hose from the pump to the steering box has a restrictive Teflon lining that has been known to melt and break free under extreme conditions. This material then travels into the pressure-side port of the gearbox, causing the system to overheat; and in some cases, causes the steering system to lock up, according to Jeff. (The Teflon liner was only installed to reduce power steering noise in the OE system.) PSC fixed this issue in the cylinder-assist kit by including a new pressure hose that doesn’t have the Teflon lining.

We worked with Dunks Performance to install a PSC four-door JK Cylinder Assist Kit (P/N PSC-SK276) on a 2014 Wrangler Unlimited Rubicon running Nitto 40s hanging off a Dana Ultimate 60. (PSC makes a similar kit for D44s.) The stock power steering system had met its match trying to turn the big tires on several difficult off-road outings. Future runs over big rocks, deep ruts, and soft sand will be a piece of cake—and with no change to our JK’s highway manners.

Jp Pro Tip: If you are running a Synergy 8002 Tie Rod, hydro-assist will accentuate any vertical flop. The remedy: Replace the Synergy tie-rod boots with their JK Low Misalignment TRE Dust Boots (P/N 4131-11) like we did during our steering upgrade. These nitrile rubber boots stop flop in its tracks.

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