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  • Black PSC steering gear assembly displayed with pitman arm and mounting hardware on a white background.
  • Black PSC steering gear assembly displayed with pitman arm and mounting hardware on a white background.
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BIG BORE XD® Cylinder Assist® Steering Gear – Jeep JK/JKU (2007–2017) – PSC Certified Refurbished

BIG BORE XD® Cylinder Assist® Steering Gear – Jeep JK/JKU (2007–2017) – PSC Certified Refurbished

$700.00
$1,450.00 $700.00
Sale Out of Stock
Shipping calculated at checkout.

Part Number: SD-SG688R

The stock JK steering box works fine—until you add bigger tires, lock it up, and actually start using the Jeep.

These are PSC BIG BORE XD® Cylinder Assist® Steering Gears (SD-SG688R) for 2007–2017 Jeep Wrangler JK and JKU, offered as PSC Certified Refurbished units.

Each unit has been inspected, rebuilt where needed, and tested to meet our performance standards. They may show minor cosmetic wear from prior use or handling, but they’re fully functional and built to perform the same as our standard units.

This gear is built for Cylinder Assist® systems, with a 45 mm sector shaft and reinforced housing to handle the extra load without flexing or failing. When you’re on 37s, locked up, and working through rocks, it keeps the steering tight and predictable—without the usual struggle at the wheel.

Pair it with a PSC High-Flow Pump and you’ll feel the difference right away—smooth, controlled, and no more fighting it every turn.

If your steering is getting pushed past what the stock box can handle, this is the fix.

All refurbished unit sales are final.

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PSC TRAIL SCORE

3/5

Weekend Warrior

Balanced for street and moderate trails—think mild rock and mud.

About:About:

Why you’ll love it

  • 45 mm sector shaft – nearly 30% bigger than stock for serious strength
  • 16:1 ratio with 80 mm piston – more torque, better road feel
  • Includes PSC proprietary Pitman arm – no guessing, no mismatched splines
  • Bolt-on upgrade – fits JK/JKU with factory mounts
  • Handles 35s without assist – and Cylinder Assist® makes it unstoppable

Tech InfoTech Info

Heads‑up for installers

  • Weight warning: This gear tips the scale at ~57 lbs. Use a jack or a buddy.
  • Track bar brace caution: If you’re running a Synergy MFG
  • Front Track Bar Brace (or similar), you must add PSC HWK-688-PP Bolt Kit (110mm). Using factory or PSC 100mm bolts can crack the case.
  • Pump matters: This gear needs a pump that can deliver ~1650 PSI and 50% more flow than stock. PSC pump kits are tuned for it.
  • Bleed it right: Front tires off the ground, engine off, cycle lock-to-lock, then recheck fluid.
  • Pitman arm note: Supplied arm has no extra drop. Some setups may need a drag link flip kit for proper geometry.
  • Recommended Tools:

    46mm Pitman Arm Nut Socket
    Pitman Arm Puller
    Tie Rod End Puller
    Axle Caster Gauge
    Pneumatic Anaerobic Thread Sealant

Fitment

  • 2007–2018 Jeep Wrangler JK & JKU
  • Direct bolt-on for factory steering gear location
  • Works with most aftermarket track bar braces (see bolt note above)

Use it with

  • PK38JP1 – High-Flow Pump Kit for 3.8L JK
  • PK36JP1 – High-Flow Pump Kit for 3.6L JK
  • PSC Cooler and Inline Filter (always a good idea on big steering systems)
  • PSC Cylinder Assist® Kit for JK (if you’re stepping up to 40s or hardcore trails)

Ideal for

  • JKs on 35s–40s
  • Rigs with front lockers or heavy bumpers/winch setups
  • Daily drivers that double as weekend trail rigs
  • Builders planning for Cylinder Assist® down the road

Specs

  • Sector Shaft: 45 mm (stock is 35 mm)
  • Gear Ratio: 16:1
  • Piston Size: 80 mm
  • Ports: Metric O-ring (PSC includes adapters in kits if needed)
  • Case: Reinforced mounting pad and housing
  • Weight: ~57 lbs
  • Includes: PSC proprietary Pitman arm

What’s included

  • (1) SD-SG688R BIG BORE XD® Cylinder Assist® Steering Gear
California Prop 65 Warning

California Prop 65 Warning

This product can expose you to chemicals including lead and di (2-ethylhexyl) phthalate, which are known to the State of California to cause cancer, birth defects or other reproductive harm.

For more information, go to www.P65Warnings.ca.gov