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SG688 - Big Bore XD Steering Gearbox for 2007-2018 Jeep JK


Quick Overview

The BIG BORE XD is the most powerful and strongest replacement steering gearbox on the market for the Jeep JK. Any Jeep JK with larger tires and/or locking front differential needs this bolt-on upgrade. The BIG BORE XD, when combined with our PK1858 XD Pump Kit, provides up to 35% more turning power over the OEM steering gearbox.  

The sector shaft diameter has been increased from 35MM to 45MM to handle the extra torque output and prevent shear in extreme duty environments. Every Big Bore XD Steering Gearbox includes a NEW proprietary Pitman arm designed for the larger sector shaft.  

Improved on-the-road driving characteristics and significantly increased torque output are achieved by using a 16:1 85MM piston assembly. This increased torque output will turn tire sizes up to 35" without the installation of cylinder assist, and will enable you to enjoy superb on-the-road handling as well as tackle 1-4 rated trails with ease.


  • 45MM Sector Shaft
  • NEW XD proprietary Pitman arm
  • 16:1 Ratio 85MM Piston Assembly
  • Reinforced mounting pad and case


Add HWK-688-PP hardware kit when installing any Synergy MFG Front Track Bar Brace (or similar) with this product.

Using the Factory or the PSC supplied bolts with a Synergy MFG Track Bar Brace could result in steering gearbox case failure.

The larger size of the BIG BORE XD Steering Gearbox may prohibit the use of some aftermarket track bars.

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