Synergy Mfg 4170-04 HD Knurled Ball Joint Kit for 2018-2026 Jeep Wrangler JL/JLU

Vehicle Fitment

• 2018-2026 Jeep Wrangler JL/JLU (2-door & Unlimited) - front suspension, heavy-duty ball joints
• 2020-2026 Jeep Gladiator JT - front suspension, heavy-duty ball joints

Features

• Fully greaseable metal-on-metal bearing design for superior durability
• Knurled upper and lower ball joint housings to fit enlarged axle end bores
• Heavy-duty high-carbon alloy steel housing (1045) for maximum strength
• Induction heat-treated 4140 Chromoly steel ball joint stud for high load capacity
• Wear-resistant nitro-butyl rubber (NBR) dust boots for extended off-road life
• Sintered graphite & oil-impregnated bronze bearing race for smooth performance under load
• Compatible with aftermarket axle shafts (including RCV), no modifications required
• 12-month unlimited-mileage warranty from manufacturer

Specifications

• Part Number: 4170-04
• Brand: Synergy Mfg
• Kit includes: 1x Upper Ball Joint + 1x Lower Ball Joint ("Knurled" style)
• Housing Material: 1045 high-carbon alloy steel
• Stud Material: 4140 Chromoly steel (induction hardened)
• Dust Boot Material: Nitro-butyl rubber (NBR)
• Fitment Years: 2018-2026 (Wrangler JL/JLU) & 2020-2026 (Gladiator JT) - final confirmation 2026 listed, 2027 not yet confirmed

Included Components

• 1x Knurled Upper Ball Joint (for vehicle specified)
• 1x Knurled Lower Ball Joint (for vehicle specified)
• Installation hardware (as supplied by manufacturer packaging)

Product Description

The Synergy Mfg 4170-04 HD Knurled Ball Joint Kit delivers a robust upgrade for front-suspension ball joints on Jeep Wrangler JL/JLU (2018-2026) and Gladiator JT (2020-2026) platforms. Designed specifically for drivers with lifted suspensions or heavy off-road use, this kit replaces the factory nylon-liner joints with a fully greaseable, metal-on-metal bearing system that dramatically improves durability, steering precision, and longevity.

Featuring high-carbon 1045 steel housings, 4140 Chromoly studs, and knurled bodies to fit enlarged axle housing bores, the 4170-04 kit is tailored to high-demand conditions. The sintered graphite/bronze races and NBR dust boots make it ideal for wet, rocky, or muddy environments. Installation is direct (1 upper + 1 lower per side), and once broken in (typically 100-500 miles), you'll experience tighter steering without the "wander" or looseness common in worn joints.

Whether you're upgrading a JL/Gladiator for large tires and rugged terrain, replacing aging joints before long expeditions, or restoring steering confidence, the 4170-04 offers a proven solution engineered for off-road performance. Professional installation is strongly recommended to ensure proper press-fit and alignment due to the knurled design and high-load application.