Overview
The Rubicon Express JK4400 is a radius long arm upgrade kit with a four-link front and three-link rear layout. It is sold as a direct fit kit.
Radius arms locate the axle and control its travel, so this kit is meant to take over that role on the vehicle it is matched to.
Key features
- Extreme-duty radius long arm design
- Four-link front layout
- Three-link rear layout
Before you install
A radius arm kit takes over the job of locating the axle, so the new arms carry the forces that the factory arms and springs handled before. Acceleration and braking loads pass through the arm mounts into the frame and axle, which makes the mounting points the first thing to inspect. Look for cracks around the brackets, worn bushings and any bolts that have loosened since the last service.
Changing the arm layout also shifts the axle’s position under the vehicle, which affects pinion angle and steering geometry. Many owners set aside time for a driveline angle check and an alignment after the arms are in. Plan for new bushings to settle, and recheck torque on all fasteners after the first several drives.
- Inspect frame and axle mounts before assembly
- Check driveline angles once the axle has moved
- Recheck torque after the first few drives
Specifications
| Brand | Rubicon Express |
|---|---|
| Part number | JK4400 |
| UPC | 70000707133 |
| Front layout | 4 link |
| Rear layout | 3 link |
| Fitment type | Direct fit |
Vehicle fitment
Confirm fit for your vehicle’s year, model and trim before ordering.
Installation notes
Changing the arm layout alters axle location and pinion angle, so alignment and driveline angles need to be checked once the kit is in.
What’s included
Check the package contents against your installation before starting.
