Thanks for the emperical data! My casual, eyeball observation had been that it seemed to self-level pretty well with various different loads, but I haven't put 1000 lbs in the bed yet. Glad to see it can keep up. (mostly) I didn't want to mess with a system that worked so well, so I was careful to get the rear shock extensions along with my Truxxx lift kit (front & rear lift) so that the shocks would still sit in the correct part of their stroke to properly self-level. So far it seems to be working great.

Thanks again for the data based observations!

 

Thanks for doing this the right way. Most people don't understand the self leveling system requires driving the vehicle for a few miles for it work its magic.

 

Yeah, from what I understood, inside the shock is basically an internal air spring, and when it detects its sagging (not quite sure on how) it will use the up and down motion of the suspension to pump up that air spring to increase the spring rate. Then when it detects the load is gone, it will deflate to reduce the spring rate and soften the unloaded ride. There are surely limits though to how much extra spring rate the air-spring can add, so naturally with enough weight the suspension will still compress but to a lesser degree than if it had no extra air-spring, and without the overly stiff truck like ride of just always driving around with an overly heavy rear spring when unloaded.

 

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.

 

Had anyone had problems with the rear suspension? Since about a year ago my rear shocks have been making noise when I go over bumps. And nothing is in the bed that will rattle. Looks like the Hyundai warranty doesn’t cover suspension. But I think I found an eibach suspension kit that supposed to lower the truck about 2 inches that’s cost the same is one Hyundai original shock. Ideas or opinions please

 

Friend with a Telluride (same self-level rear shocks) had what sounded like a rear wheel bearing go out, turned out to be the shock mounting point insulation had degraded and it was covered by the warranty. So yes, struts/shocks are 'maintenance' items unless they prematurely fail, but are you sure it's the strut/shock that failed?

 

I have not inspected it yet, so I am not 100% sure. I’m just preparing for the worst possible scenario which would be to replace the shocks.

 

A few around here have report squeaky rear shocks and as @Norskie said it was piece of mounting hardware that was replaced under warranty.

FYI - the aftermarket kits are not self leveling.

 

You mention an after market rear shock replacement kit. Could you provide more information on that kit. I don't need the self leveling, and want to get rid of the noise from the rear shocks. They were replace recently and still make noise. Thank You

 

I finally inspected my rear shocks and they are leaking badly. I bought the extended warranty and apparently fly they are considering it covered. So I’ll be taking to to the Dealer to handle that. Hopefully it is handled quickly.