In Part 1 of our "Faster Raptor" series in which we're updating our first-generation 2013 Ford F-150 SVT Raptor, we walked through the process of installing a new set of 3.0-inch coilover shocks and billet-aluminum front upper control arms from ICON Vehicle Dynamics. The performance gains from shelving the factory front shocks were immediately noticeable and quite stunning. Naturally, this also worked to amplify the shortcomings of the rear suspension.
In the process of building our Raptor into the ultimate whoop-slaying, prerunning, overlanding, backcountry machine, we added a lot of weight to the bed of the truck. To compensate for this we again turned to the experts at IVD, this time for the company's RXT rear leaf springs and 3.0-inch bypass shocks. The RXT springs, when used with the provided add-a-leaf, are designed to compensate for up to 600 pounds of weight carried in the bed of the truck, which is about the same as we've calculated to have been added to the rear of our Raptor.
The RXT springs and shocks can be used independently, however, to get the most out of the system, they need to be paired. And when used together, the system really does impress. Working with the help of a buddy (the springs are quite heavy), we were able to install the new springs and shocks in long day in the driveway with basic handtools. The results are a leveled ride height, an increase in travel of about 25 percent (from 12 inches to 15), and incredible off-road performance. While on a recent excursion to test the new suspension, we were able to run through moderately deep whoops and rutted trails at highway speeds without upsetting the beverages in our cupholders. To say it is smooth would be a gross understatement.
While we're deeply impressed with the improvement so far, we're not quite done yet. Tune in next time as we complete the suspension reboot with ICON's rear hydraulic bumpstop kit.
| The factory first-generation Raptor rear suspension was relatively simple and worked really well. Springs were a soft two-leaf pack with an overload, and they were paired with 2.5-inch Fox internal bypass shocks. This combination produced 12 inches of rear suspension travel.
| Once out of the truck, the rear shackle can be removed from the factory springs. Save the shackles and hardware, noting the orientation during removal, as they will be used on the new ICON springs.
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| With the axle loose, the springs can be removed from the truck. First, remove the lower shackle mount bolt (shackle to frame attachment) at the rear of the spring. Next, move to the front bolt. After removing the nut, this bolt must be cut in order to be removed due to interference from the fuel tank (driver side) and muffler (passenger side). New bolts are included with the ICON springs.
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| Next, with the axle supported, the factory U-bolts can be removed and discarded. The factory lift block will also not be reused. Set the lower U-bolt plate to the side, as it will be reused with the new ICON springs.
| The first step in the installation process is to raise the rear of the truck, remove the wheels, and safely suspend the vehicle on jackstands. Now the factory Fox shocks can be removed. Be sure to retain the upper and lower mount hardware, as it will be reused.
| Desiring more suspension travel, increased load-carrying capacity, and improved durability, the team at ICON Vehicle Dynamics developed the RXT spring pack. These springs are multi-rate and come with new U-bolts, a replacement front hanger bolt, an additional add-a-leaf, and bumpstop extensions.
Spring Rate Change
One of the best features of the ICON RXT spring system is the ability to change the spring rate. Using the included add-a-leaf, the spring rate can be increased by either 10 or 20 percent. Counting from the bottom up, replacing spring number five with the add-a-leaf will increase the rate by 10 percent, which adds 1.25 inches of lift or compensates for 300 pounds of constant weight in the bed. Adding the leaf in the number six position will increase the rate by 20 percent, which adds 1.75 inches of lift or compensates for 600 pounds of constant weight.
| While a rate change can be performed with the springs on the truck, we opted to set up the springs prior to installation. Because of our desire to carry two spare tires, tools, and a Dometic fridge in a custom rack in the bed, along with our ARE bed cap, we opted to install the add-a-leaf for maximum spring rate. We started the process by clamping the upper springs together and removing the cross bolts from the spring retainers.
| Next, the two center pins can be removed. Because of the nature of the pins, we needed to use a pair of Vise-Grip pliers to keep them from spinning while removing the nut that secures them.
| An additional spring separator is included with the add-a-leaf. These separators work as an isolator, which reduces both noise and friction.
| Using a clamp to hold the spring pack together, along with the provided extended center pins, the spring pack gets bolted back together with the new spring now added to the pack.
| When observed side by side, the differences between the factory Ford spring pack and the ICON RXT pack become glaringly obvious. One of the main features of the RXT springs is the addition of a rebound leaf, which was added to reduce axlewrap.
| The RXT springs also feature a triple military wrap front eyelet, which increases both durability and safety. The rear eyelet receives a half wrap. Bushings are OE-style bonded rubber, which are both maintenance- and squeak free.
| Because the ICON RXT springs are made up of nine individual leaves instead of two like the factory pack, the factory lift block is no longer needed.
| Installation of the ICON RXT springs is the reverse of removal of the factory springs. Using the provided bolt, first install the front spring eye. Next, attach the rear shackle to the frame mount. Finally, raise the axle up to meet the springs and bolt the pair together with the provided U-bolts. Repeat for the opposite side. It pays to have a buddy handy, as these springs are heavy.
| While the RXT springs can be used with Ford's factory Fox shocks or with myriad other aftermarket dampers, the most improvement is found when paired with ICON's RXT 3.0-inch rear triple-bypass shocks. The biggest difference you may have noticed is the side-mounted upper eyelet, which allows for more suspension travel and longer-stroke shocks while retaining the factory upper shock mounting location.
| Part of the magic of the RXT bypass shock lies in the placement of the upper eyelet. Because of its placement on the shock body, ICON added a patent-pending anti-wobble link. This link provides the needed stability to prevent the body from rotating, keeping the bypass tubes clear of the springs and tires.
| To clear the anti-wobble link, a small section of bed floor support needs to be removed. Following the detailed instructions, we broke out the trusty angle grinder and set to work.
| After the initial cuts were made, we used a small flat file to deburr the rough metal edges.
| With the RXT shocks installed, you can clearly see the function of both the anti-wobble link and the clearance notch that was cut to clear it.
| To secure the RXT shocks' large remote reservoir, ICON includes this bracket, which mounts to a bed support rib. A single self-tapping screw holds the bracket in place while holes are drilled for the remaining three bolts.
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| The 3.0-inch RXT bypass shocks feature large knobs for easy bypass tube adjustment without the need for tools. Each bypass valve is individually equipped with unique spring rates and uses damped valve stops for quiet operation.
| Speaking of the remote reservoir, these RXT shocks are equipped with ICON's patent-pending dual-hose recirculating reservoir. These units use a one-way check valve to circulate hot fluid from the shock body to the reservoir while returning cooled fluid to the body. What this equates to is a shock that operates more stably and is less prone to performance degradation and fade during continuous hard use.
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| The finished product not only performs great, but it looks wicked cool as well!
| You may have noticed one piece missing: the bumpstops. Included with the RXT spring kit are spacers for the factory microcellular jounce stops. However, to get the full value and suspension travel from the RXT system, ICON's rear hydraulic bumpstop kit is needed. More on that next time