JKS Manufacturing J-Flex Adjustable Rear Upper Control Arms

2018–2026 Jeep Wrangler JL

Part #: JKS1666

Overview

The JKS Manufacturing J-Flex Adjustable Rear Upper Control Arms are engineered specifically for the 2018–2026 Jeep Wrangler JL, delivering enhanced suspension geometry and improved ride comfort. Designed for Jeep enthusiasts who demand both on-road refinement and off-road capability, these control arms allow precise adjustment to maintain proper alignment and suspension articulation. By upgrading to JKS J-Flex arms, Wrangler JL owners can expect a quieter, smoother driving experience with increased durability and articulation for tackling challenging terrain.

These rear upper control arms are ideal for those seeking to optimize their Jeep’s suspension performance without sacrificing comfort or reliability. Whether you’re upgrading your stock suspension or building a capable off-road rig, the J-Flex arms provide a robust solution that balances strength, adjustability, and noise reduction.

Key Features

JKS J-Flex Adjustable Rear Upper Control Arms combine innovative design with premium materials to enhance your Jeep’s suspension system. Key features include:

• Adjustable length design for precise suspension geometry tuning
• Heavy-duty 2” OD x .250-wall DOM tubing for superior strength and durability
• CNC bent tubing for added clearance and optimized fitment
• OE-style rubber bushings at the axle mount to absorb noise and reduce vibrations
• Unique hex-shaped threaded bung at the frame-side for easy adjustment
• Forged flex end with 1-1/4”-12 threads jam nut for secure locking
• Flex end design allows up to 30 degrees of misalignment (15 degrees each direction) for exceptional articulation
• Greaseable flex ends to extend bushing life and maintain smooth operation
• Rebuildable flex ends for long-term serviceability
• Durable gloss black powder coat finish for corrosion resistance and lasting appearance
• Backed by JKS’s limited lifetime warranty for peace of mind

Construction & Design

The J-Flex control arms are constructed from heavy-duty DOM (Drawn Over Mandrel) steel tubing measuring 2 inches in diameter with a .250-inch wall thickness, ensuring exceptional strength and rigidity. The tubing is CNC bent to provide additional clearance around suspension components and obstacles, preventing interference during articulation.

At the axle mount, premium OE-style rubber bushings are employed to isolate road noise and vibrations, delivering a quieter and more comfortable ride. The frame-side mount features a forged flex end with a unique hex-shaped threaded bung, allowing for straightforward length adjustments and secure locking with a jam nut. This design accommodates up to 30 degrees of misalignment, enabling impressive suspension articulation without compromising durability.

Installation & Fitment

Designed as a direct fit replacement for the rear upper control arms on 2018–2026 Jeep Wrangler JL models, the JKS J-Flex arms install with basic hand tools and no major modifications. Their adjustable length allows for fine-tuning suspension geometry after installation, ensuring optimal alignment and handling characteristics. The greaseable flex ends simplify maintenance and extend the lifespan of the bushings, while the rebuildable design offers long-term serviceability.

What's Included

• Pair of JKS J-Flex Adjustable Rear Upper Control Arms
• Grease fittings installed on flex ends
• Jam nuts for secure adjustment locking
• Installation instructions

Ideal For

The JKS J-Flex Adjustable Rear Upper Control Arms are perfect for Jeep Wrangler JL owners who want to improve suspension articulation, maintain proper geometry after lift kit installation, or enhance ride comfort and noise reduction. They are well-suited for off-road enthusiasts, daily drivers seeking better handling, and anyone looking to upgrade their Jeep’s rear suspension with durable, adjustable components.

JKS Manufacturing builds Jeep and off-road suspension parts—lift systems, control arms, track bars, disconnects, and supporting hardware—engineered for articulation and durability. It’s a popular choice for Wrangler and Gladiator owners looking to improve clearance, ride quality, and capability for real trail use.