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PSC Steering

PSC Steering Performance Steering BIG BORE XD Steering Gear Conversion – Jeep TJ LJ (2003–2006) SG400R | SG400R

$925.75 19% off MAP Pricing
$1,150.00

Big Bore XD Cylinder Assist Steering Gearbox 2003-06 Jeep LJ/TJ 

The factory Mercedes ZF box on ’03–’06 TJ/LJ Wranglers? Weak. Small piston, thin case, and a bad habit of giving up when you add bigger tires or a locker. The BIG BORE XD Conversion Gear fixes all that with a Saginaw-style box, a bigger piston for more torque, and ports for Cylinder Assist when you’re ready to step up.

This isn’t a quick swap—it’s a proper conversion. You’ll need the right hoses, maybe a little steering shaft work, and in some cases a 1" body lift for clearance. But once it’s in, you’ll have a steering gear that can handle real trail abuse without crying uncle.

  • This is a conversion. It’s not a 30-minute swap. Plan for hoses, shaft mods, and maybe a body lift.
  • Hose kit required: Use PSC HK2000 Hose Conversion Kit for a clean install.
  • Intermediate shaft: Factory shaft usually needs to be shortened ~2". Or install Jeep/MOPAR PN 52078705.
  • Clearance: Some rigs need a 1" body lift to clear the bigger gear and lines.
  • Ports: Metric O-ring, machined for -6 AN fittings to Cylinder Assist®. No welded junk here. 
  • Fluid: PSC recommends PSC 715 for best performance and component life.

  • Stronger Saginaw design – replaces the failure-prone ZF box
  • Bigger piston = more torque – turns big tires without a fight
  • Cylinder Assist ready – ports are machined into the case, not welded
  • Billet aluminum top and end caps – built for strength and serviceability
  • 14:1 ratio, 3.25 turns lock-to-lock – quick response without twitchy road manners

 

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