Striking the right balance between smooth ride and confident handling has always been a challenge for chassis designers. Especially in a motorhome, a smooth ride means soft shock absorbers and small sway bars, which results in excessive sway in corners, and “porpoising” over bumps. Aggressive shock valving and larger sway bars can result in good handling, but also a jarring, noisy ride over rough roads and railroad crossings.
For years, SuperSteer parts and our service division, Henderson’s Line-Up www.hendersonslineup.com have worked diligently to create the best handling/ride improvement solutions for our customers–to the point that we never stop researching and testing new products and technologies that can address a specific issue. We now offer several suspension/handling products for specific motorhome chassis, the most common of which today is the Ford F-53. SuperSteer offers Trac bars, Koni shock absorbers and larger sway bars that really transform this motorhome, and these can be added either individually or as a package as your needs and budget allow. Visit http://supersteer.wpengine.com/f53-kits/ or, for a complete list of products available for the Ford F53, check out http://supersteer.wpengine.com/products/motorhome–rv/class-a/f-53-chassis/index.html
One product that is creating a real buzz among RV owners right now is the Liquid Spring CLASS® suspension system, which stands for Compressible Liquid Adaptive Suspension System https://liquidspring.com/ford-f-53-rv-suspension/. CLASS does away with the original leaf spring/shock absorber suspension, replacing it with a five-link rear suspension, strut modules containing a compressible fluid as the spring/damping medium, large reservoirs for each strut module (called secondary volumes) and a sophisticated on-board microprocessor that monitors driving conditions. Like the adaptive suspension systems available in some of today’s finest luxury vehicles, CLASS allows for automatic and instantaneous (40 milliseconds) change of spring stiffness and damping at each rear wheel, which gives the system the ability to reduce ride harshness and reduce sway. A driver interface allows the user to adjust modes and suspension height.
We test drove a Ford F-53 Class A motorhome fitted with the Liquid Spring CLASS system in the past and were impressed with the results. Although it is not available for the front suspension yet (we will let you know when it is), we found that the coach road much more smoothly and more quietly than the stock suspension and did yield much improved handling. But without having any other suspension set-ups to compare it to, we couldn’t be sure how much of an improvement the system offered compared to traditional suspension upgrades like a SuperSteer Trac Bar, Koni shock absorbers and Roadmaster sway bars. The only way to find out was to conduct our own testing.
To get the ball rolling, we talked to our old friend, Wayne Wells. Wayne has a long history in the motorhome suspension business, and we have worked on many projects together over the years. He recently started working at Liquid Spring, and was also interested in conducting some testing with us. So he agreed to visit us at our headquarters in Grants Pass, Oregon and arranged for Gary Ford, the Vice President and Director of Engineering of Liquid Spring, to fly in from Los Angeles to assist in the installation and provide his technical expertise.
First, we needed to establish a baseline. Our 2016 Tiffin Alegro on a Ford f-53 chassis had served as a testbed for a number of SuperSteer and other products/kits for quite a while, and at the time of the Liquid Spring installation it had been fitted with a combination of components that yielded great handling and stability. These include:
- SuperSteer Quad shock kit with four Koni FSD (Frequency Selective Damping) shock absorbers, part number 8805-1018
- SuperSprings Sumo Spring Rebel helper springs, part number SSF-173-40-2
- Roadmaster 1-3/4-inch diameter front sway bar, part number 1139-140
- Safe-T-Plus steering stabilizer, part number 1139-140
- Koni FSD shock absorbers, #8805-1019
- SuperSteer Quad Shock mounting kit, part number SS2426R
- Ultimate Dual Rear Auxiliary Sway Bar system, part number SS293
- SuperSteer Trac Bar, part number SS525
We fitted the test coach with a variety of sensors to monitor suspension travel. This would be useful not only to measure the suspension movement over bumps, but also around corners. We first collected this data with all of the above components installed, then with four shocks (two front, two rear), SuperSteer sway bars and Trac Bar, then with stock suspension. Finally, the Liquid Spring system was installed and monitored on the same roads at the same speed. This would give us a comprehensive view of how the Liquid Spring system works compared to the stock suspension as well as to readily-available bolt-on products.
Because the Liquid Spring is a complete rear suspension system, not a product that is added to the existing system, installation is permanent and is quite involved. On average, installing the Liquid Spring System takes 30 hours to complete, which typically comes to $12,000-$13,000 in total with parts and labor factored in. Let’s go through the installation and then we’ll get to the results.
Before any testing was initiated, the motorhome was fitted with an array of sensors and data acquisition equipment to measure suspension movement before and after the Liquid Spring system was installed.
The Liquid Spring system is very comprehensive and includes heavy duty mounting brackets, upper and lower control arms, track bar and all necessary mounting hardware.
The Liquid Spring system also uses large external reservoirs (called secondary volumes) to provide the struts modules with a constant supply of compressible silicon fluid. The fluid has a wide temperature range, so it can cope with any weather a motorhome may encounter.
The first step is to remove the original leaf springs, starting with the U-bolts. Note that these are the lower plates for the SuperSteer Dual auxiliary sway bars; the original plates look different.
We use the biggest jack stands you’ve ever seen to support the frame so the rear axle can be lowered and raised as needed to install of the CLASS Suspension System.
John Henderson of SuperSteer and Gary Ford of Liquid Spring pull the original leaf springs out next. This is definitely a two-man job!
The original spring perches are cut off, then the top of the axle housing ground smooth. This is necessary so that the new control arm bracket fits flush to the axle tube.
The brake line boss that secures the brake line to the rear axle housing is also cut off and ground smooth. The new lower control arm bracket has a provision for re-attachment.
Next, the front upper and lower control arm bracket is mounted to the frame using existing holes.
Two brackets for the strut secondary volumes are mounted on the outside of the frame on either side.
With the secondary volume mounted (passenger side shown, looking rearward), the massive 1-inch I.D. (or dash 16) diameter hose is routed rearward, over the axle to the strut module mounting location. It incorporates a rate valve that controls the interaction of fluid between the strut and secondary volume.
Mounted between the reservoirs on the inside of the driver’s frame rail is the power module with ECU, which integrates the pump, motor, manifolds, control valves, filters, low pressure reservoir and ECU in one, compact unit. It comes already mounted to the bracket and pre-filled with the compressible silicone fluid. The unit monitors and processes various vehicle signals and motion at each wheel and instructs each strut module to change its stiffness and damping characteristics as required.
Here, both the reservoir mounting brackets have been mounted on the passenger side (looking rearward) and the clamps installed in preparation for the secondary volumes.
Power for the control unit comes from a wire harness underneath the dash. Identifying them takes some time depending on the coach.
Power for the power module uint is supplied by a fused connection at the positive battery terminal. Liquid Spring supplies the connector which is then crimped onto battery positive.
The controller fit perfectly on the left side of the dash and is secured by two-sided tape. Note that the user can select Sport, Normal or Comfort ride modes, and five ride height settings.
Because the weight of the coach will now be supported by struts instead of leaf springs, a massive substructure is installed between the two frame rails at the rear of the coach, tying the two frame rails together and substantially increasing structural rigidity. This step requires several holes to be drilled into the frame on either side using a special piece of equipment called a magnetic frame drill. Note that the bolts have been left loose; they will not be tightened until all the other components have been fitted.
Here, the upper and lower control arms have been installed. Normally, the stock leaf springs control axle wrap-up (where the rear axle tries to turn upward under acceleration), but since they have been removed, the control arm system is employed. As the axle tries to turn, the top bar pulls while the bottom bar pushes, helping to transfer weight rearward under acceleration and preventing axle wrap-up.
The reservoirs are made from heavy steel and are filled with the compressible silicone fluid, so they are very heavy. The shop forklift worked perfectly at lifting the reservoir in place while Gary positioned the reservoir and tightened the clamps.
Next, the system’s track bar is located. This bar bolts to the substructure on the driver’s side, and to a bracket on the passenger side that is welded to the top of the rear axle housing. Bolting it in place first helps determine correct location before the bracket is welded.
Here the bracket has been welded. Note that Liquid Spring supplies this bracket with the end nearest the housing unpainted, as the paint would burn away during welding anyway. Once the weld cools it is painted black to match the bracket and to prevent rust.
Finally, the struts are installed and connected to the hydraulic hose from each reservoir.
With everything in place, all of the fasteners are finally torqued to spec and the installation complete.
On our first test drive, we noticed there was less road noise, and low-speed body roll was practically eliminated. By the seat of our pants, we didn’t notice a notable improvement in high-speed sway compared to our quad shock/dual sway bar set-up, but the graph provided by Liquid Spring did show a small improvement on the two sharp turns we used for comparison on our test route.
The Liquid Spring system was originally developed to reduce ride harshness, so it was no surprise to us that the system provided a significant improvement here. In fact, it shows there was actually a 32% increase in shock and vibration over the stock suspension when striking a large pothole with our quad shock and dual sway bar kit installed, and an 11% increase over stock when driving over a large bump. This is caused by the spring wrap-up effect of the larger sway bars. The Liquid Spring CLASS system provided a 37% and 45% decrease, respectively.
What we learned is that the CLASS system is amazing for low-speed sway control and ride quality, while our Ultimate Dual Sway Bar/Quad Shock system really shined at higher speeds. Working with Wayne Wells and Gary Ford from Liquid Spring, our Tiffin Alegro handled better than any other Ford F53 chassis motorhome they had ever tested. That allowed us to see where we could possibly make some programming changes to improve the high-speed handling characteristics of the CLASS system. We’re confident that we can make this game-changing product even better.
Anyone that wants to drive an F53 with amazing handling characteristics should make an appointment to take a test drive in our Tiffin and prepare to be astounded by the improvements affected by our SuperSteer upgrades to the front suspension and the Liquid Spring CLASS system on the rear. Check our rally/show schedule https://www.hendersonslineup.com/rvshows and make arrangements if you aren’t going to be in Grants Pass, Oregon soon. Whatever system you choose, our goal is always to help our customers get the most out of their motorhome.