Bolt-On Suspension Performance
Regular shock absorbers are boring, yet they do an adequate job of controlling most suspensions on- and off-road. Cellular foam shocks, the kind included with your standard suspension lift kit, are the norm. These dampers offer bolt-in installation and do a decent job over smooth surfaces, but tend to fade quickly when trying to control heavy tires and wheels over irregular surfaces.
At the other end of the spectrum are race-oriented shocks with remote reservoirs for increased fluid volume to resist fading, bypass tubes to tune compression and rebound independently, and the ability to control suspension movement over rough terrain at incredible speeds. The problem is that high-end race shocks are difficult to package under most vehicles due to their size and mounting requirements. As a result, they require custom fabrication and expert tuning that is beyond the budget of most wheelers.
Fortunately, Icon Vehicle Dynamics (IVD) bridges the gap by offering high-end, race-quality shocks that bolt directly into popular vehicles. Their adjustable height front coilovers are available for a variety of Ford, Dodge, Chevy, Toyota, and Nissan 4x4s. These popular coilovers provide more than just lift for larger tires; they are valved for the specific application—no one-size-fits-all mentality here. Other race-inspired features include billet aluminum end caps, cadmium-plated shock bodies to resist corrosion, and the ability to rebuild or revalve the shocks to your specifications. They are made entirely in the USA.
Recently, IVD introduced bolt-in rear shocks to compliment the company’s line of proven front coilovers and also introduced rear dampers for ’97-’02 (third-generation) 4Runners. This is a platform that shares the front suspension with the widely supported Tacoma, but instead of using simple leaf springs in the rear the 4Runner uses coil springs located by a four-link and a Panhard bar. The low floor in the back of the 4Runner is great for getting your gear and tools in and out, but it leaves little room for larger rear shocks underneath the vehicle. As a result, this platform has been nearly ignored by the aftermarket. Some owners have gone so far as to add custom hoops and bypass shocks outside of the frame or through the cab, but neither of these options is ideal. Putting the shocks into the interior takes up valuable cargo room and also means that the cab is no longer sealed. Mounting the shocks outside the frame requires the wheels to be spaced out and any additional wheel travel is negated in order to keep the tires from hitting the fenders on compression.
IVD has made all of these compromises unnecessary with its rear 4Runner shocks, which use upper bar pins to bolt into the stock mounting locations.
Our test 4Runner was previously upgraded with Light Racing Jounce shocks before IVD rear shocks were available, but we still needed a shock that can complement our Jounce shocks and put up with the hard use our 4Runner is subjected to. Placement of the piggyback reservoir on the rear shocks not only allows for easier fitment, but it also results in a 20 percent increase in compression in the last 2 inches of travel to prevent harsh bottoming. We headed to IVD dealer Samco Fabrication for the installation, which was easily completed in half a day.
Josh Ogg of Samco Fabrication used a pickle fork to remove our tubular upper control arms. This is the only specialized tool necessary for the front install. If you use uniball upper control arms from Total Chaos, Camburg, or All-Pro, you can simply unbolt the upper control arm.
The threaded shock collar on the Icon Vehicle Dynamics coilovers allows anywhere from zero to 3 inches of lift. This allowed us to level our 4Runner front-to-rear and account for our aftermarket bumper and winch. The upper mounting bracket for the coilovers is machined from a single piece of aluminum, which makes for a strong and light suspension mounting point.
IVD coilovers are available to work either with the factory upper control arms or with aftermarket tubular control arms. Factory arms use a quiet, long-wearing ball joint, while aftermarket arms use a high-travel uniball that complements the IVD coilovers with additional wheel travel.
The rear springs and factory suspension links were retained with the new IVD shocks. The IVD rear shocks use a larger shock body, larger shaft, and a remote reservoir for increased performance over a variety of terrain when compared to factory and common aftermarket shock absorbers.
The rear upper shock pin is one of the keys to the bolt-in installation of the IVD 4Runner shocks. Most race-quality shocks use spherical rod ends at each end and leave the mounting up to the end user. On the other end of the shock, IVD uses high-quality 5⁄8-inch Teflon-lined FK rod ends instead of urethane bushings. This provides less deflection while allowing a wider range of motion.
IVD uses a shock dyno to tune all of its shocks for specific applications. The area on the right side of the graph where the curve gets steeper represents the “bump zone” in the last 2 inches of travel to prevent harsh bottoming.
The rear shocks utilize a Schrader valve for nitrogen charging. The shocks come charged to 250 psi and should only be checked with a screw-on manifold gauge to ensure that minimal charge is lost.
The rear shocks come fully pressurized, which means that you do not need to add nitrogen after the installation. The downside is that they are nearly impossible to compress. Samco’s Austin Tischler used a jack under the axle to line up the shock mounts during installation.
The reservoir is on the fixed end of the shock and will not move relative to the frame. Cycle the suspension through the full range of travel to ensure that the suspension components and axlehousing do not contact and damage the reservoir before heading to the trail.
Once the shocks were installed we were eager to test them out. It wasn’t long before our hired stunt driver was airing out the 4Runner and running over rough terrain at speeds that would have been impossible.
Installing & Testing
The front coilovers can be installed at home with handtools; however, an alignment should be performed afterward. With a 250-psi nitrogen charge in the rear shocks, we found it beneficial to position the chassis and the axle independently to line up the shock mounting locations. This was much easier on a two-post lift; however, if you have access to a nitrogen source, the shocks can be discharged, installed, and recharged at home. To take advantage of the additional travel available with our new rear IVD shocks, we also needed to extend our rear sway bar end links and purchase a longer rear brake line.
Installation complete, we were eager to hit the desert and push the shocks through rough terrain. We hadn’t even made it off the pavement before the difference is suspension handling was apparent. The higher spring rate of the chrome silicone coil springs and the flutter-stack in the 21⁄2-inch front dampers provided a controlled ride and eliminated the brake dive that we previously experienced. Once we hit the dirt, the benefits continued. While the compression damping was noticeably improved, the change in rebound was dramatic and made the 4Runner much more stable at speed. The new IVD rear shocks also minimized the sway our 4Runner previously exhibited over a variety of terrain.