Flexstasy: BDS Four Link Suspension for the Ford Super Duty

Pickup truck fans were riveted when Ford trotted out the 2008 Super Duty. Compared to its predecessor, there were numerous changes to the vehicle that included a bold new exterior look with a 4-inch-taller hood height. Under the rig, the front coil spring/radius arm suspension was tweaked for better steering feel, improved braking, and a reduced turning circle. Out back, the rig got a new rear leaf spring suspension with 8-inch-longer leaves. The result was a pickup that was incredibly refined but notably rugged. It was so good that it won our 2008 Four Wheeler Pickup Truck of the Year competition.

As is often the case in the truck world, the aftermarket has found ways to make this great truck even better. BDS Suspension, based in Coldwater, Michigan, offers a variety of kits for the 2008-'10 Super Duty F-250/F-350 ranging from 1- to 8-inch lifts. One of those kits is this 4-inch system we installed, which replaces the factory radius arms with a four-link system. Why would you want this? Two words: wheel travel.

Stock

Glen Hard, BDS engineering manager, says, "Our goal was to maximize wheel travel and increase off-road performance while maintaining the vehicles street mannerisms." In addition to the increase in wheel travel, BDS notes that replacing the radius arms with a four-link system dramatically reduces caster change through wheel travel. This translates to reduced steering wheel feedback during high speed off-road maneuvers as well as reduced coil bow created by the swinging arch of a radius arm. "We replaced a single boxed arm with two massive DOM control arms that not only slide nicely over rocks, but also distribute the forces created while off-roading," Hard notes.

This particular kit was installed by the folks at Attitude Performance in Arlington Heights, Illinois, on a customer's vehicle. Technician Blake Vanderheyden completed the install, which was straightforward and harbored no nasty surprises. Here's an overview of the major components of the BDS four-link kit and how they install.

RTI Before

Bottom Line
The owner of this rig replaced the stock LT275/70R18 (32.1-inch-diameter) Continental Contitrac TR tires with 35x12.50/20 Nitto Trail Grappler M/Ts. Combined with the lift, the Super Duty gained approximately 5 1/2 inches of front air dam-to-ground height (16 1/4 inches to 21 3/4 inches) and approximately 1 3/4 inches of trailer hitch-to-ground height (20 1/4 inches to 22 inches). Approach angle improved by approximately seven degrees and departure angle improved by approximately four degrees. Even though the new four-link brackets hang down approximately 2 1/2 inches further than the stock radius arm brackets, the bracket-to-ground measurement improved by approximately 3 1/4 inches.

The even bigger story was on the RTI ramp. In stock form, the 137-inch-wheelbase Super Duty climbed 58 inches up our 20-degree ramp to earn a score of 423 points. After the BDS four-link install, the Super Duty climbed an impressive 79 1/2 inches up the ramp (with the sway bar connected) to earn a score of 580 points. This 21 1/2-inch improvement on the RTI ramp shows just how well the BDS kit frees up front wheel travel.

RTI After

We tagged along on a brief test drive of the Super Duty and were impressed at how well the truck drove on the paved road. The front end was smooth and stable, and it tracked very well. BDS says with 10 inches of front wheel travel, there's less than one degree of caster change, thus it's easy to understand why this translates to outstanding steering control over rough terrain.

At the time of print, the kit we installed was advertised on the BDS website for an MSRP of $2,133.83. The same kit with new rear leaf springs has an MSRP of $2,934.89.

Two versions of the 4-inch four-link kit are available. We installed the version with rear lift blocks, but there is also a system with new leaf-spring packs. BDS also offers 6- and 8-inch-lift four-link kits.
Two versions of the 4-inch four-link kit are available. We installed the version with rear
The first step is to remove the wheels, the track bar at the frame mount, the brake line brackets from the axle, the sway bar end links, the shocks and steering stabilizer.
The first step is to remove the wheels, the track bar at the frame mount, the brake line b
The factory track bar bracket is removed, as is the drag link from the pitman arm. The pitman arm is then removed (shown) so the new, longer pitman arm can be installed. Tip: It's important to ensure that all of the factory threadlocking compound is removed from the OE nut and sector shaft so the new threadlocking compound included with the kit will adhere properly.
The factory track bar bracket is removed, as is the drag link from the pitman arm. The pit

Next step: lower the axle and remove the factory coil springs. Here's what the frontend looks like with the springs removed.
Next step: lower the axle and remove the factory coil springs. Here's what the frontend lo
Included is a new, longer track bar bracket made from 1/4-inch steel, and it mounts in the factory location using the five factory bolts. Here you can also see the new, longer pitman arm installed.
Included is a new, longer track bar bracket made from 1/4-inch steel, and it mounts in the
Bumpstop extensions mount between the bumpstop cups and the vehicle's frame to compensate for the added suspension height.
Bumpstop extensions mount between the bumpstop cups and the vehicle's frame to compensate

The stock radius arms are 1/8-inch thick, and each is held in place with three bolts. Both factory radius arms are removed and discarded.
The stock radius arms are 1/8-inch thick, and each is held in place with three bolts. Both
Large polyurethane bushings with metal sleeves mount in the frame-end of each new upper and lower control arm. The ends are also tapped for greaseable zerks, which are included with the kit.
Large polyurethane bushings with metal sleeves mount in the frame-end of each new upper an
In order to fit the new BDS four-link frame mounting brackets, the factory radius arm frame mounts have to be removed. This is the most challenging part of the install because each factory mounting bracket is fastened to the frame with seven rivets. These rivets must be ground, drilled, or chiseled completely out and they're very stubborn. BDS says not to use a torch because the factory undercoating is highly flammable. Further, fuel lines travel inside the driver-side framerail. Here you can see the driver-side framerail with the factory mount removed.
In order to fit the new BDS four-link frame mounting brackets, the factory radius arm fram

The new four-link frame mounting brackets are made from 1/4-inch steel, and they're designed to mount using the factory holes that were previously occupied by the rivets, so there's no drilling required. New hardware is included. Here you can see the driver-side bracket installed.
The new four-link frame mounting brackets are made from 1/4-inch steel, and they're design
Behind the driver-side framerail is a fuel module and it needs to be spaced away from the frame to make room for the new four-link frame mounting bracket bolts. Pictured here is the fuel module spacer plate that's included for that purpose.
Behind the driver-side framerail is a fuel module and it needs to be spaced away from the
Beefy 2-inch-diameter upper and lower control arms mount to the axle and frame brackets using supplied hardware.
Beefy 2-inch-diameter upper and lower control arms mount to the axle and frame brackets us

New 2 1/2-inch sway bar drop brackets are included with the kit, and they mount between the factory sway bar and the frame using the factory hardware.
New 2 1/2-inch sway bar drop brackets are included with the kit, and they mount between th
Here's the finished front suspension. There are a few things noteworthy here. The 4-inch-lift coil springs are specific for our diesel-powered application, and the shocks are the optional BDS 9500 Series gas-charged units. Also, note how the new upper control arms are designed with tabs for attaching the ABS wires. Finally, notice that the kit comes with new brake-line brackets and hard brake-line extensions.
Here's the finished front suspension. There are a few things noteworthy here. The 4-inch-l
The rear of the truck is lifted via 5-inch blocks and they utilize built-in bumpstops. They replace the stock blocks. The instructions direct how to align the center pin in the rear hole of the block to ensure that the axle is moved slightly forward and the wheels are aligned properly in the wheelwells. The kit contains new U-bolts and plates and the owner of this rig chose to upgrade to the BDS 9500 Series gas-charged shocks (the kit comes standard with 5500 Series hydraulic shocks). The 9500s feature a brushed stainless appearance, a 46mm piston, urethane bushings, and Correct Application Valving (CAV), which BDS says is based on extensive shock dyno and ride control research.
The rear of the truck is lifted via 5-inch blocks and they utilize built-in bumpstops. The

SOURCES
BDS Suspension Inc Coldwater MI 517-279-2135 www.bds-suspension.com	Attitude Performance 2349 E. Oakton ST. Arlington Heights IL 847-593-0505 www.attitudeperformance.com