ow vehicle suspensions play a vital role in ride quality, safety and the ability to handle hitch and overall weight imposed by a trailer or fifth wheel. Owners who tow with a pickup truck must pay attention to axle ratings, gross vehicle and combination weight ratings and towing capacity. Typically, trucks have enough payload to handle most trailers on the market, but in many cases, the springs don’t have enough “backbone” to keep the truck on a level stance under heavy — or maximum — loading, like towing a big fifth wheel.
That can be dangerous. Too much rear-end sag can impact front-axle loading, headlight aiming and handling — to the point where safety can be compromised. Unfortunately, too many owners end up with a truck that doesn’t meet expectations when it comes to towing. A case in point: a new RV owner who purchased this 2022 F-350 long-bed truck to tow a 38-foot fifth wheel. The rather large fifth wheel had 3,800 pounds of pin weight and the rear axle payload was rated at 5,600 pounds. Although Ford claimed the truck could handle the 5,600 pounds, the rear end still sagged when the fifth wheel was hitched — which in turn forced a nose down attitude for the trailer.
According to the manufacturer, the RAS reduces bounce and wheel hop when towing or hauling, and rear-end bounce was unmistakable on the project truck. The RAS is also designed to prevent body roll from side to side and improve axle wrap when heavy loads are placed on the truck. Also, there was no need to deal with air springs, which don’t prevent side-to-side sway. The RAS suspension provides a variable-rate tension coil that applies proportionate force as the weight is applied. This unique design, when adjusted properly, does not affect the ride of the truck while it’s empty. If weight changes, the capacity can be adjusted with common wrenches. No drilling or welding is required as the kit comes fully assembled — and the company provides a 30-day money-back guarantee.
The Installation
Figure on spending a couple hours, at most, to install the parts. The process starts by setting chocks on both front tires, then the rear end is jacked up to remove the wheels — always use jack stands. The RAS kit comes fully assembled right out of the box, so it’s just a matter of placing the parts on the existing springs and bolting them down. You’ll first place the RAS eye-bracket hook over the leaf spring rear wrap eye and proceed with an adjustment of the gold threaded rod inside the tension spring. The gold threaded rod is set at approximately 5 to 6 inches for shipping purposes and will need to be lengthened to accommodate positioning of the round spacer that will be placed in front of the spring-pack U-bolts to hold the RAS extension brackets in place.
Make sure that the bolt and the spacer are located directly under the leaf spring pack, which is very important. The instructions do not provide a torque value for the bolt and spacer, but we tightened the bolt to 75 ft.-lb.
The next step was to adjust the coil spring to the correct tension. Before doing this, we made sure that the eye bracket was in the center of the rear leaf-spring hanger. Two nuts that are on the threaded rod were adjusted using a 14mm ratcheting wrench and a standard 24mm wrench. These two nuts were snugged together when the kit was assembled from the factory and were adjusted by holding the threaded rod stationary and turning the coil spring until the gap between the coils started to open.
That’s it; job completed, and the rear wheels can be put back on and the lug nuts tightened to factory specification.
Since this was the first RAS we installed, it took about two hours to get it right, but the install is straightforward. The kits run between $539 and $589 and are backed by a 5-year warranty.
Does It Work?
A resounding “Yes!”. Overall, the truck handles much better — and after the RAS components were installed, the suspension bounce and annoying porpoising were virtually eliminated. And there was a noticeable, 3 ¾-inch improvement in rear-end sag when the fifth wheel was hitched. Nothing changed when the truck was running solo because the RAS gear remains idle until loaded.
You will likely want to “fine tune” the spring tension after a few miles of towing, which only takes a few minutes. For this project, the RAS system has worked flawlessly during more than 20,000 miles of fifth-wheel towing. The owner of the truck was happy with his decision to pass on the overload springs, which were more than compensated for with the installation of the RAS hardware.
