JKS JSPEC142KFA 3.5in J-Kontrol HD Lift Kit FOX 2018-2025 Wrangler JL 4-Door

Vehicle Fitment

• 2018-2025 Jeep Wrangler JL Unlimited 4-Door (Sport, Sport S, Sahara, Rubicon, Willys, High Altitude, Freedom), 4WD

Fitment Notes

• Does not fit 2021-2025 Jeep Wrangler JL 4xe models - see JKS 4xe-specific lift kit
• Does not fit Wrangler JL Rubicon 392 models - see JSPEC160KFA for Diesel/392 applications
• 4-Door (Unlimited JL) only - for Standard Rate coil spring variant see JSPEC141KFA
• Rubicon models: shock extension brackets can be used with factory FOX 2.5 shocks, but will slightly limit suspension down travel
• HD Rate coil springs are recommended for builds carrying heavier loads - winch/bumper combos, rear-mounted full-size spare, roof rack, or significant accessory weight
• Factory wheels cannot be reinstalled without wheel spacers after lift
• Maximum recommended tire size: 35x12.50 (Sport/Sahara/Willys); 37x12.50 (Rubicon with 5" backspacing)

Features

• JSPEC Heavy Duty dual-rate front and rear coil springs specifically tuned for the 4-Door JL platform at 3.5" lift - engineered to handle winch/bumper combos, full-size spares, and roof racks without sagging
• Custom-valved FOX 2.0 Adventure Series IFP monotube gas shocks matched to this JL J-Kontrol 3.5" HD system
• Front Control Arm Correction Brackets (heavy-duty, fully boxed 7GA steel - JKS6201) flatten upper and lower control arm angles to correct caster and mimic factory suspension geometry
• Retains OE control arms - no replacement arms required
• JKS front adjustable track bar and rear track bar bracket correct axle positioning at lifted ride height
• JKS2033 Quicker Disconnect front sway bar links unlock up to 30% more front axle articulation on the trail
• Rear extended sway bar links correct operating angle and improve strength at lifted height
• Front and rear bump stop extensions properly limit suspension up-travel at lifted height

Specifications

• Lift Height: 3.5 inches
• Platform: Jeep Wrangler JL Unlimited 4-Door (2018-2025)
• System Level: J-Kontrol (step above J-Venture - adds Front Control Arm Correction Brackets)
• Shock Series: FOX 2.0 Adventure Series IFP (custom-valved for this system)
• Spring Type: JSPEC Heavy Duty dual-rate coil springs (HD Rate - front JSPEC1352, rear JSPEC1358)
• Control Arm: OE arms retained; geometry corrected via fully boxed 7GA steel correction brackets (JKS6201)
• Max Recommended Tire Size: 35x12.50 (Sport/Sahara/Willys); 37x12.50 (Rubicon)
• Recommended Wheel Backspacing: 5 inches
• Installation Type: Bolt-on, no cutting or drilling
• Warranty: Limited Lifetime (JKS components); FOX Shocks covered by FOX limited warranty
• Made in USA

Included Components

• 2x JSPEC Heavy Duty Dual-Rate Front Coil Springs (HD Rate - JSPEC1352)
• 2x JSPEC Heavy Duty Dual-Rate Rear Coil Springs (HD Rate - JSPEC1358)
• 2x FOX 2.0 Adventure Series IFP Front Shocks - FOX98450323 (custom-valved)
• 2x FOX 2.0 Adventure Series IFP Rear Shocks - FOX98450327 (custom-valved)
• 1x Pair Front Control Arm Correction Brackets (7GA steel, fully boxed - JKS6201)
• 1x JKS Front Adjustable Track Bar
• 1x Rear Track Bar Bracket
• 1x Pair JKS2033 Quicker Disconnect Front Sway Bar Links
• 1x Pair Rear Extended Sway Bar Links
• 1x Set Front and Rear Bump Stop Extensions
• 1x Installation hardware pack

Product Description

The JKS JSPEC142KFA is the Heavy Duty coil spring variant of the 3.5" J-Kontrol suspension lift system for the 2018-2025 Jeep Wrangler JL Unlimited 4-Door. Identical in system architecture to JSPEC141KFA, this kit swaps the standard-duty JSPEC coil springs for Heavy Duty dual-rate springs - front JSPEC1352 and rear JSPEC1358 - specifically wound to handle the additional static load of front winch bumper combos, rear-mounted full-size spare tires, roof racks, and other substantial accessory weight without compromising lift height or ride quality. For heavily built JL 4-Doors, the HD springs maintain the intended 3.5" lift height under load where standard springs may settle.

Like all J-Kontrol systems, the defining upgrade over J-Venture is the inclusion of heavy-duty fully boxed 7GA steel Front Control Arm Correction Brackets, which lower the frame-side mounting point of the front control arms to flatten their operating angles and mimic factory suspension geometry at 3.5" of lift - improving on-road handling and correcting caster without replacing the factory arms. Custom-valved FOX 2.0 Adventure Series IFP shocks, a JKS front adjustable track bar, JKS2033 Quicker Disconnect sway bar links, and rear extended sway bar links complete the system. Does not fit 4xe or Rubicon 392 models.