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  • Black PSC steering gear assembly displayed with pitman arm and mounting hardware on a white background.
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BIG BORE XD® Steering Gear - Jeep Wrangler JK / JKU (2007-2018)

BIG BORE XD® Steering Gear - Jeep Wrangler JK / JKU (2007-2018)

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

Part Number: SG688R

Do you want Cylinder Assist® Now for Future Plan?

The stock JK steering box? It’s fine for stock tires and errands. But throw on 37s, a locker, and a weekend in Moab, and that thing’s begging for mercy. The BIG BORE XD is the fix—built with a beefy 45mm sector shaft and a reinforced case so it won’t twist, crack, or cry when you crank it hard. Pair it with a PSC High-Flow Pump Kit and you’ll feel the difference the first time you turn the wheel—smooth, strong, and no more arm wrestling at the trailhead.

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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

  • 45mm sector shaft – nearly 30% bigger than stock for serious strength
  • 16:1 ratio with 80mm 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: 45mm (stock is 35mm)
  • Gear Ratio: 16:1
  • Piston Size: 80mm
  • 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

  • BIG BORE XD® Steering Gear (SG688)
  • PSC proprietary Pitman arm
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