Overview
The Rubicon Express RE4000 is a driver side front lower adjustable long arm in the Extreme-Duty line, sold as a single arm. It is used with the RE4020 arms to change a factory four link into a radius arm design.
The arm is built from 2-inch by 1/4-inch wall 4130 chromoly with Super-Flex joints and a gray powder coat finish. It is designed to help ride, handling and driveline geometry on a lifted Jeep.
Key features
- Driver side front lower long arm
- Adjustable length
- Super-Flex joints for axle articulation
- Constructed from 2-inch by 1/4-inch wall 4130 chromoly
- Gray powder coat
Radius arm geometry
Radius arms control the axle’s fore and aft movement, and they change how the axle reacts to acceleration and braking. The arm’s length and mounting angle set how much the axle rotates as it moves, so both arms must match. Even a small difference can push the axle to one side and make the vehicle track poorly on the road.
Set the arms to the same length and check the pinion angle at ride height. Inspect the chromoly welds and the Super-Flex joints after early trail runs, and look for chips in the gray powder coat where rock contact can start corrosion. Touch up exposed areas promptly, and recheck the setup any time the lift height or tire size changes.
- Match arm length and angle on both sides
- Check the pinion angle at ride height
- Touch up chipped powder coat promptly
Specifications
| Brand | Rubicon Express |
|---|---|
| Part number | RE4000 |
| UPC | 614901441000 |
| Position | Driver side, front lower |
| Arm type | Long arm, adjustable |
| Material | 4130 chromoly, 2 in x 1/4 in wall |
| Joints | Super-Flex |
| Finish | Gray powder coat |
| Quantity | Single |
Vehicle fitment
Confirm the Jeep model and year that match your vehicle before ordering, since the arm is sized for a specific setup.
The arm is designed to be used with the RE4020 arms for a radius arm setup, so those parts are needed as well. Confirm your vehicle’s year, model and trim before ordering.
Installation notes
Set both sides of the radius arm setup to the same length and angle so the two arms line up.
What’s included
One driver side front lower adjustable long arm.
Not included: the passenger side arm and the mounting hardware.
