The truck ads on TV look so cool with a 4WD romping over ruts and sloshing through deep mud. But face it. Factory suspensions just aren’t built for that kind of regular abuse, nor will your shocks last long with that kind of punishment.
So, one of the best things you can do for your truck is upgrade the shocks to something that can better damp heavier tires running over rugged terrain. Enter the new Fox Performance Series of off-road shocks. These application-specific shocks lie somewhere between the marginal stock vehicle shocks and full-bore race units in both price and performance. We recently visited Fox Racing Shox at its off-road service center in Santee, California, to witness the installation of a set of new Performance Series (Internal Floating Piston) IFP shocks on our F-150 2WD project truck. As delivered, the adjustable nitrogen-charged coilovers yield about 2 inches of front lift which leaves the truck close to level.
Along with the front coilovers, we added a pair of Performance Series IFP smooth-body shocks to the rear of the truck. These bolt right on quickly, and offer a big improvement at the tail of the truck. The late model F-150 already has a decent suspension from the factory., but Fox was able to improve upon that performance and setup the suspension so that it’s more suited for tackling some rough dirt. The slightly firmer spring rate helps, without making the ride overly stiff.
We also added a set of 33x12.50R17LT sized Interco Vortrac tires after the Fox install. This is an all-terrain-type tire with a fairly aggressive sidewall tread. This size fits well in the fenderwells of a 2WD F-150, especially with the front raised and the truck leveled out.
The Performance Series shocks feel a bit firmer than stock on surface streets and seem to work together well with upgraded Vortracs. Jump off pavement and this is where you really notice the benefit of the firmer spring rate. The shocks soak up the bumps well and keep the factory suspension under better control through whoops and bumps.
01. This is Fox’s new Performance Series line. Coilovers adjust for different ride heights by simply spinning the spring collars up or down the threaded shock body. Tightening the spring preload raises the ride height, but does not affect the spring rate of the shock. Both coilover and smooth-body shocks utilize aluminum bodies that save weight and offer effective heat dissipation over the conventional steel body shocks. The shocks are valved to match a number of production vehicles to optimize performance per specific application.
02. Just below the top aluminum mount plate is a polyurethane isolator puck that helps cushion the upper shock mount point to quiet the shock movement and make the action a little smoother. Full metal-to-metal mounts may be fine for race applications, but street driven vehicles can benefit from a little built-in isolation.
06. Here’s a side-by-side comparison of our stock F-150 unit and the Fox coilover. The Fox assembly uses industry standard 3-inch coil springs and is a bit more compact than the stock unit. The coilovers utilize an internal floating piston (IFP) design. Oil resides on the shock rod side of the internal piston and high-pressure nitrogen resides on the other side. Since the Fox coilovers come completely assembled, there’s no need to bother with swapping springs around.
07. The top of the coilover mates to the top strut mount with three studs; same as the factory unit. New hardware is included. Below, the shock eye is positioned and new hardware installed. It is usually necessary to pry downward a bit on the upper A-arm to install the bolt in the lower end.
08. Here’s the finished assembly with the new Fox coilover in place. We should also mention that the shocks can be rebuilt and revalved as needed by Fox or by off-road shops that service Fox shocks. The front Performance Series IFP coilovers for the 2WD F-150 use a slightly stiffer spring than the stock strut. The new spring rate is 650 pounds per inch versus 600 for the stock springs.
09. The rear shocks took only a few minutes to install and fit perfectly. Both front and rear shocks use redundant seal packs, and wiper and scraper seals to best keep dirt out and oil inside the shocks. The shock rods are 5/8-inch hard chrome plated and the assemblies are designed for good longevity for the street driver and weekend warrior off-roader.
10.0 We added a set of Interco Vortrac tires in a 33x12.50R17LT size. Interco is known for making some of the most aggressive dirt tires ever. But, they also manufacture the all-terrain Vortrac in sizes ranging from about 33 to 37 inches to fit wheel diameters from 16 to 22 inches.
10.5 The tread of the Vortracs uses a fairly tight lug pattern to keep the noise down and offer good tread life. It’s enhanced with some side-biter tread at the outer edges and the tread is siped to increase traction in wet and snowy conditions.
|Interco Vortrac Specs |
|Height:|| 33 inches|
|Overall Width:|| 12.7 inches|
|Tread Width:|| 9.8 inches|
|Tread Depth:|| 16/32 inches|
|Weight:|| 63 pounds|
|Plies:|| Tread=10, Side=2|
|Max Load:|| 3,085 pounds|