No guarantee but likely the SC rear shocks are using the patented Nivomat technology. I was interested in it, read it, and this weekend had a chance to test it. The below pictures show the empty standard ride height 38”, then I loaded 960 lbs of softener salt it dropped to 35.5”. If felt “wiggly” in the rear as I pulled out, within a mile about it seemed to stabilize and the vehicle tightened up noticeably. After an 18 mile interstate run at 70mph I unloaded and the rear suspension was up to 36.5”. Pointless to state the specifics of what my QX56 can handle but its rear air leveling suspension can just level back out if I keep the tongue weight below 500ish lbs so I’m impressed with this system providing an inch lift with 1000 lbs in the bed. I doubt it’s design is supposed to lift to original ride height anyway. The bed lifted to 38 3/8” as soon as I unloaded, forgot the final pic but you’ll have to trust that after 3 miles to the next store it had settled back to right at 38”. Tire temperature for those interested stabilized quickly on the interstate at 39psi indicating around a 25ish degree increase in tire temprature.
Maz
This website describes the shocks: Nivomat Shock Absorbers: Self-Leveling Monotube Ride Control Units it appears to use oil and air pressure to control the leveling motion.
Based on the diagrams of the shock's internals I believe this is how it works:
The leveling is controlled by a two valves, one is set as the "low" position while the other is set at as the "high" position. When the shock moves up or down during normal driving an internal diaphragm passes one of the valves depending on the load (weight of the vehicle). In this new position a bypasses condition occurs. During bypass the internal shock damper sends pressure into a different area of the shock tube which pushes the whole shaft up or down. This action will raise or lower the vehicle (like pumping the handle of a floor jack) until the opposite end of travel is reached by the shaft - which causes the opposite valve to become the bypass. As the vehicle continues bouncing along at some point the pressure equalizes and diaphragm remains inside a "normal" zone between the two valves - and then the vehicle is level again. If the load changes (IE: you add or remove weight) the shock will move outside the normal zone causing the whole process to repeat again. Regardless of direction (up or down) the system is always trying to stabilize in the normal or level zone if possible.
The system is brilliant in simplicity as it uses the natural way shock absorbers / dampers already work. The only difference is the pressure created by the shock compression is redirected by the valves to increase or decrease the overall lift force of whole system. I can only imagine that driving in the low position would result in excessive wear on the valves or diaphragm. This might be where the infamous 660# weight limit for the bed comes from, but that is pure speculation on my part.
Most the articles I found reference Volvos but other OEMs use these type of shocks.
Based on the diagrams of the shock's internals I believe this is how it works:
The leveling is controlled by a two valves, one is set as the "low" position while the other is set at as the "high" position. When the shock moves up or down during normal driving an internal diaphragm passes one of the valves depending on the load (weight of the vehicle). In this new position a bypasses condition occurs. During bypass the internal shock damper sends pressure into a different area of the shock tube which pushes the whole shaft up or down. This action will raise or lower the vehicle (like pumping the handle of a floor jack) until the opposite end of travel is reached by the shaft - which causes the opposite valve to become the bypass. As the vehicle continues bouncing along at some point the pressure equalizes and diaphragm remains inside a "normal" zone between the two valves - and then the vehicle is level again. If the load changes (IE: you add or remove weight) the shock will move outside the normal zone causing the whole process to repeat again. Regardless of direction (up or down) the system is always trying to stabilize in the normal or level zone if possible.
The system is brilliant in simplicity as it uses the natural way shock absorbers / dampers already work. The only difference is the pressure created by the shock compression is redirected by the valves to increase or decrease the overall lift force of whole system. I can only imagine that driving in the low position would result in excessive wear on the valves or diaphragm. This might be where the infamous 660# weight limit for the bed comes from, but that is pure speculation on my part.
Most the articles I found reference Volvos but other OEMs use these type of shocks.
I would get them replaced under warranty again, they should not make any noise.
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