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2018 Jeep Wrangler JL with JSPEC™ J-Rated 3.5" Lift System

JKS J-Flex Rear UCA Kit for Jeep JL

Coldwater, MI — JKS Manufacturing adds to its lineup of suspension upgrades for the 2018-2020 Jeep Wrangler JL with new J-Flex rear adjustable upper control arms. These rear J-Flex UCAs join the rest of the J-Flex to allow you to fully upgrade all 8 control arms for a significant improvement to the stock JL control arms both in strength and performance. The arms are constructed from 1.5” OD x .120" DOM tubing and feature robotically welded ends to ensure precision welds and strength. At the axle mounted end OE-durometer premium quality Clevite rubber bushings are preinstalled for great durability, quiet operation and better isolation of road noise and vibrations. At the other end a forged flex joint is threaded in allowing plenty of adjustability for use with with a wide range of lift heights. The forged flex joints use a 1.25”-12 threaded shank along with a jam nut to lock down the length while allowing 30-degrees of misalignment for impressive articulation. Servicing is easy via the grease fitting at the base of the joint.

The adjustable design allows for correctly position the rear axle while correcting pinion angle at a wide range of heights from stock height up to 6” of lift and are a direct bolt-in with all Jspec suspension systems for the Jeep JL. These arms come fully assembled right out of the box finished in a gloss black powder coat. Get more out of your Jeep JL with JKS.

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New Product:

J-Flex Rear UCA Kit for Jeep JL

Kit ID Number(s):

#1666 (J-Flex Rear UCA Kit for Jeep JL)




2018-2020 Jeep Wrangler JL 2 Door

2018-2020 Jeep Wrangler JL 4 Door

J-Flex Rear UCA Kit for Jeep JL Features:

  • High strength 1.5" x .120" wall DOM construction.
  • Adjustable design utilizes a forged flex joint and jam nut.
  • Specially formed for proper tire, frame, and axle clearance.
  • Axle mount uses OE-style rubber bushing to isolate NVHs.
  • Adjustable for use with 0-6" lifts
  • Fully assembled, ready to install right out of the box.

Related Kits/Products:

  • #1616 - J-Flex Front UCA Kit
  • #1625 - J-Flex Front LCA Kit
  • #1661 - J-Flex Rear LCA Kit

Available Accessories:

  • #1696 - 1-1/2" Jam Nut Wrench


© JKS Manufacturing

About JKS: Since 1989, JKS Manufacturing has developed some of the most widely used and respected products for Jeep vehicles in the off-road industry. From the original Quick Disconnect™ brand of quick-release swaybar disconnect systems, to the innovative ACOS Pro™ variable height coil spring spacer with integrated bump shock, JKS® only manufactures products that provide unquestionable benefits to vehicle performance. It's no coincidence that those who know Jeep performance best choose JKS products for their own vehicles.

JKS Manufacturing, 491 W. Garfield Ave. Coldwater, MI 49036

(517) 278-1226 | |


Factory Protection Plus Badge

The Ultimate Lifted Suspension Protection Coverage and it’s FREE!

Limited Lifetime Warranty
Factory Protection Plus
  • 5 Year, 100,000-mile PLUS Protection
  • Free, no cost protection for JKS customers
  • Could save thousands on possible repairs
  • Easy online application process
  • Available for most late model vehicles
Drivtrain 5year 60K Mile Protection Drivetrain Warranty

A 5 year - 100,000-mile plus drivetrain warranty is available for Jspec equipped vehicles as a Supplemental Drivetrain Limited Warranty to match your new vehicle express drivetrain limited warranty Jeep. The protection applies to any Jspec eligible suspension systems purchased on or after November 1st, 2013.

Drivtrain 5year 60K Mile Protection
What is FMVS No. 126?

When you see the FMVSS Compliant Symbol you will know with confidence this application has been tested and successfully passed the Federal Motor Vehicle Safety Standard No. 126 compliance test. This highly specialized test was performed to prove the installation of the particular Jspec suspension system, with specified wheel and tire package will not compromise the performance and effectiveness of the vehicle’s Electronic Stability Control (ESC) system keeping you safer on the road.


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