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ORI STX Coil-Over CJ-7 Conversion

Posted in How To: Suspension Brakes on August 18, 2016
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The DP3 hill-sensing struts hit the market in January 2003 and put Off-Road Innovations (ORI) on the off-road enthusiast map. However, that wasn’t the real beginnings of ORI, as owners Mark and Marie Jensen were racing and eventually building sand rails as early as the late ’70s. Their homegrown company evolved as their need for better suspensions grew. Soon the next step, the ST model, was released in 2005. This new design was much simpler and more user friendly, as well as less expensive, than its predecessor, all of which boosted business. Their entry into the off-road racing arena brought to light issues of heat dissipation as well as the effects of the temperature on the nitrogen charge, and thus, the STX strut was born in 2008. This third generation of the ORI strut continues to be produced today.

How It Works
There are two different pressure chambers in the STX strut. The upper chamber dictates ride height and carries the weight of the rig, while the lower chamber’s pressure applies an opposing force on the struts piston. This opposing force is how ORI struts control the stability and body roll of the rig. It doesn’t allow the strut to unload as weight shifts while traversing steep side hills, awkward climbs, and puckering descents.

The three-stage compression damping of the STX is velocity sensitive—the ride can go from soft to firm as the speed of the piston changes. There is also a seven-position externally adjustable rebound-damping feature that can be set using dial near the bottom of the strut. Those features, along with easy nitrogen filling, make the ORI STX strut easy to tune.

Easy Tuning
Tuning ORI struts is simple and can be done on the vehicle as there are no springs to swap out. Instead, nitrogen pressure is added or removed in most cases. Depending upon the weight of the rig, terrain, and driving style, ORI struts can be fine-tuned to handle almost any situation. A general tune can be dialed in to handle most driving conditions, and if you’re more particular about the off-road versus on-road performance, your rig can be tuned in less than 10 minutes for street driving, rockcrawling, general trail riding, or screaming across the desert. Reservoirs are an option that can be added to STX during or after purchase. Adding the reservoir after purchase requires rebuilding the strut, and ORI recommends that to be done by ORI or one of their dealers.

We’re going to show you how to install and adjust a set of ORI STX struts on a CJ-7, but for the rig that needs the ultimate equipment for extreme situations, a high-performance desert ORI strut was just released for 2016. This newest version of the ORI strut sports improved cooling features, higher capacity integral or remote reservoirs with up to five stages of damping, 24-position adjustable compression dampening, and seven-position rebound dampening. These “desert” units are built for abuse on the racecourse. However, development at ORI continues, and it’s already back in the lab working on something new, so stay tuned.

This cutaway view of an ORI STX strut shows the dual pressure chamber and valve system. It also features an internal hydraulic bumpstop at full compression, as well as a hydraulic end of stroke stop. This eliminates the need for limiting straps and auxiliary bumpstops.
The CJ-7 had coilovers on it when purchased used; however, it was difficult to determine the valving setup, and they didn’t work very well. Revalving would have required complete disassembly, and it may have taken many attempts to get the valving just right. Spring rates are also a factor in coilover performance. The shocks that came on the CJ-7 were not adjustable coilovers, so getting the right setup on four new springs (about $65 each) by changing springs in and out could have become expensive quickly.
Ride height is checked before and after the installation of the new ORI STX struts. The CJ-7 always sat about 1/2 to 3/4 inches lower on the driver side. The ability to tune the ORI STX struts allows for slightly different pressures left to right. The upper chamber of the struts should always be charged so that the rig sits level, as recommended by Off-Road Innovations in the company’s detailed installation and setup instructions.
Once the old coilovers were removed, the Jeep was set to full stuff (fully compressed) so that the ORI STX struts could be properly installed.
ORI struts are a compact design and have roughly the same outside dimensions of a 2-inch-diameter coilover shock. If you can fit a coilover, then there is no doubt the ORI STX struts will slip right into place. Real estate is hard to come by under the CJ-7 with a custom 56-inch-wide Dana 44 to match the factory CJ-7’s width. A proper coilover setup would also need to have a dynamic bump stop and limiting straps to prevent damage, adding extra cost and needing more space. The ORI STX struts have internal hydraulic bump stops for limiting compression and extension. The upper and lower pressure chamber design also eliminates the need for anti-sway bars for most applications.
The compressed and extended dimensions of all sizes of the ORI STX struts are comparable to that of a 2-inch-diameter coilover, and the piston shaft is a robust 1 3/4 inches in diameter. Notice the seven-position rebound dampening adjustment screw on the base mount just below the shaft.
The provided misalignment spacers were just a tad too wide to fit in the mounts that were already on the CJ-7. Luckily there was some extra meat on them, and after a little bench-top grinder action, they slipped into place without a hitch.
If you are already running coilovers or air shocks on your Jeep, then the mounting of an ORI STX strut is easy. Out with the old and in with the new! Two bolts and done. If your Jeep is not set up to mount ORI STX struts, there are companies such as Synergy and TNT Customs that make bracket kits specifically for the Jeep JK models. Those kits do require a lot of set up and welding for installation—some assembly required, in other words. For CJs, YJs, and TJs, there are many universal mounting kits/brackets available in the aftermarket, but they also require some fabrication skills to get set up properly.
It’s important that the ORI STX struts are left in the compressed state, as they came out of the box, during installation. There is shock oil in each chamber, and cycling the struts before adding nitrogen pressure could displace some of the oil. At this point, no nitrogen is added. Notice the machined ribbing that helps keep the struts cool during rapid and extended periods of use.
After the struts are mounted and fully compressed, nitrogen is added to the bottom chamber first. ORI recommends starting with 90 psi the first time around. High pressure in the bottom chamber will resist piston movement and make for a stiffer ride but will be more stable. A lower bottom chamber pressure allows the piston to drop out more easily, and provide a softer ride but will be less stable. The upper chamber must be empty and the strut at full compression when adding or removing pressure in the bottom chamber for an accurate fill. The pressure in the bottom chamber rises significantly as the strut extends.
After the bottom chamber has been set to the desired pressure, the upper chamber can be filled until the desired ride height is achieved.
For heavier rigs and high-speed off-road activity, ORI offers integrated and remote reservoir options. When a reservoir is added it is possible to have three, four, or even five stages of modular compression damping, depending on your performance needs. The reservoir setup also allows for a 24-position external rebound damping adjustment. The added oil capacity keeps the struts cooler and resists performance fading during extreme use. Many strut color options are available. The anodized coating helps protect the units from corrosion.
Here’s a tip we’ve learned from experience. To fill the struts with nitrogen, a fill kit is necessary. High-pressure braided lines are also a must when working with up to 3,000 psi of nitrogen. The fill kits seemed expensive, and we thought for sure we could piece one together to save some coin. Our biggest mistake was trying to avoid the $45 special no-loss nitrogen chuck that is included in this pictured ORI fill kit. That mistake resulted in a bent Schrader valve on one of the struts and two broken standard push type air chucks as well. It was also tough to fill the strut with any level of control. When everything was said and done, after we bought the special nitrogen chuck, we were within $25 of just buying an ORI fill kit. We had also spent time and fuel running all over town trying to piece one together, not to mention having to replace one Schrader valve. Our advice: Just buy the fill kit from ORI and don’t try to pinch pennies.
First impressions during our post-install testing left a smirk of joy. The CJ-7 soaked up the bumps and jolts from rolling over the rocks, resisted bouncing, and provided a cushy landing that kept driver and passenger from getting seasick. No creaking coilover springs or puckering on side hills. Don't confuse this performance with stiff, though. The suspension flexed nicely and was smooth as butter on the straightaways.
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Off-Road Innovations (ORI)

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