The rear end of a 2022 Ford Bronco 3.5 inch lift build is where things start to come together. In this installment, Spence and Marissa from Core 4x4 install the bronze powder-coated rear control arms, rear track bar, and Falcon 3.5 inch coilovers on their Eruption Green Wild Track — the same Bronco that got the front suspension treatment in the next episode. If you are doing a Bronco lift, the rear goes on first, and this guide covers arm adjustment, install sequence, torque specs, and the Falcon coilover swap.
Fitment: 2021+ Ford Bronco (all trims). This build is on a 2022 Wild Track with the factory Trailhawk one-inch lift, going to 3.5 inches total.
Parts Used in This Build
This rear suspension install uses a combination of Core 4x4 control arms and Falcon shocks, all color-matched in Method bronze to complement the Method wheels going on later:
- Rear lower control arms (pair) — Core 4x4 adjustable arms with Johnny Joints, bronze powder coat. These set your wheelbase by centering the axle in the wheel well.
- Rear upper control arms (pair) — Core 4x4 adjustable arms with Johnny Joints. These set your pinion angle to keep the driveline straight and avoid vibrations.
- Rear track bar — Core 4x4 adjustable track bar (panhard rod). Centers the rear axle left-to-right under the truck.
- Falcon 3.5 inch coilovers (rear pair) — adjustable reservoir coilovers with included mounting bracket for the eyelet-to-frame connection.
Shop Bronco Rear Suspension Kit
Setting Control Arm Lengths Before Install
Before bolting anything onto the Bronco, Spence sets all the arm lengths on the bench. This saves time under the truck and ensures both sides start at the same length. Here are the starting measurements for a 3.5 inch lift on the Ford Bronco:
| Component | Starting Length (vs. Factory) |
|---|---|
| Rear lower control arms | 1/4 to 1/2 inch over factory length |
| Rear upper control arms | About 1/2 inch over factory length (depends on pinion at ride height) |
| Rear track bar | 1/4 inch over factory length |
Critical: Starting length matters, but what matters more is that your left and right arms match. Spence sets one arm first, then lays the second arm on top and adjusts until both bolts drop in freely. Any adjustments you make later should be made equally on both sides to keep the axle centered.
Upper Arm Note: The S-Curve
The Bronco rear upper control arms have an S-curve to clear surrounding components. Core 4x4 accounts for this by using Johnny Joints at each end — the joints sit at a slight offset angle and flex through the range of motion without binding. This is one of the reasons Johnny Joints are preferable to polyurethane bushings in a Bronco rear setup.
Passenger Side Install and Gas Tank
Spence installs the passenger side first for a practical reason: the gas tank. In the teardown video, the gas tank had to be dropped to access the upper control arm bolt. By completing the passenger side and torquing everything down, the gas tank can go back up and out of the way for the rest of the build.
Installation is straightforward — the new arms bolt directly into the factory mounting points. The Johnny Joints on Core 4x4 arms have an independent crush sleeve, which means you can torque the bolts with the Bronco in the air at full droop. This is a significant advantage over rubber or polyurethane bushings, which must be torqued at ride height to avoid preload.
Torque Specs for Bronco Rear Control Arms
| Fastener | Torque Spec |
|---|---|
| All control arm bolts (upper and lower) | 160 ft-lbs |
| Jam nuts (final tightening) | 250 ft-lbs |
Important: Torque the control arm bolts to 160 ft-lbs during install, but leave the jam nuts loose. Final jam nut torque (250 ft-lbs) happens after the front is lifted, the tires are on, and the truck is sitting at ride height under its own weight. That is when you can properly center the wheel in the wheel well, dial in your pinion angle, and lock everything down.
Why You Can Torque Johnny Joints in the Air
Rubber and polyurethane bushings have the sleeve fused to the rubber. If you torque them at full droop, the sleeve locks in that position and creates a preload that destroys the bushing when the suspension cycles. Johnny Joints and polyurethane bushings with an independent crush sleeve do not have this problem — the bolt clamps the crush sleeve, not the joint itself, so you can torque at any suspension position.
Driver Side and Track Bar Install
With the gas tank back in place, the driver side goes in using the same process. Then the track bar mounts between the axle and the frame. The track bar is set to a quarter inch over factory length as a starting point — final centering happens once the Bronco is back on its wheels.
Falcon Coilover Install
The Falcon 3.5 inch coilovers replace the factory rear shocks. There are two differences from the factory setup:
- Top mount: The factory coilovers use a top hat that bolts directly to the frame. The Falcon coilovers use an eyelet-style mount, so Falcon includes a bracket that bolts to the frame and accepts the eyelet. Install the bracket first, then bolt the coilover to it.
- Axle side: Falcon includes spacers that allow the new coilovers to bolt directly into the factory axle brackets. No modification needed.
Spence notes that you may need to disconnect the sway bar to get enough droop for the new coilovers to slide in. On this Bronco, the factory sway bar end links are extremely short — the shortest Spence has ever seen — so Core 4x4 is making longer Crawl Series end links to replace them. If you are lifting a Bronco, longer sway bar end links are essentially required to let the sway bar sit at the correct angle.
Final Adjustments at Ride Height
With the rear suspension fully assembled, the Bronco already looks transformed. However, final adjustments are not made yet. Here is what happens once the front is lifted, the tires are on, and the truck is sitting under its own weight:
- Center the wheel in the wheel well — adjust the lower control arms equally on both sides until the tire sits centered front-to-back in the wheel opening.
- Set the pinion angle — adjust the upper control arms until the driveshaft and pinion are aligned. Even a slight misalignment causes vibrations and premature U-joint wear.
- Center the axle left-to-right — adjust the track bar until the axle sits centered under the body with equal spacing on both sides.
- Torque the jam nuts — once all adjustments are dialed in, torque every jam nut to 250 ft-lbs.
- Get an alignment — the alignment shop handles the final fine-tuning.
What Each Rear Component Does
If you are new to solid-axle rear suspension, here is a quick breakdown of why each component matters on the Bronco:
- Lower control arms: Control where the axle sits front-to-back (wheelbase). When you lift a Bronco, the axle shifts rearward — longer lower arms bring it back to center.
- Upper control arms: Set the angle of the differential pinion relative to the driveshaft. Wrong pinion angle equals driveline vibrations and accelerated wear on U-joints.
- Track bar (panhard rod): Centers the axle left-to-right. On a lifted truck without an adjustable track bar, the axle shifts to the driver side and the truck crab-walks down the road.
- Coilovers: Support the weight of the truck at the new ride height and control the damping through the suspension travel. The Falcon units have an adjustable reservoir for tuning compression and rebound.
Frequently Asked Questions
Related Content
- 2022 Ford Bronco Front Suspension Install — 3.5 Inch Lift — the front-end companion to this rear suspension build, covering Falcon coilovers, Icon UCAs, and heavy-duty tie rod ends
- Core 4x4 Ford Bronco Rear Suspension Kit — the K5 rear control arm and track bar kit used in this build
- Why You Need Control Arms — educational overview of what control arms do and why upgrades matter on any solid-axle vehicle
Shop Ford Bronco Parts
Fitment: 2021+ Ford Bronco (all trims). Product questions: sales@core4x4.com | (385) 375-2104
