Need some help with shock logic for trailers

[UK4X4]

As you know I have the airbag shock arrangement with my lightly loaded trailer

It never sits still on the highway, it bump steers/shimmies over every ripple in the road.

I used some spare bilstiens from the rear of a disco 2 but I don't think that
the gas pressurised and the airbags go together that well.

Ie both the shock and the bag are pushing in the same direction, when I touch the trailer even fully loaded, it moves way too easy.

I'm even thinking of adding limit straps and pressurising up against then on the road sections.

Now the movement is not that much, but I can see it all the time.

even up to 85 miles an hour its still there- you can't feel it in the car
but you can see the shimmying around in the mirrors.

Its not speed wobbles or rythmic, its just alive !!!!

 

[Tucson T4R]

I don't understand what the difference is but the independent suspension on my KK is extremely stable. I get almost zero sway and it is dead steady in my mirrors when towing on a variety of road conditions and speeds. When I do hit a one tire dip or bump, even a nasty one at speed, the trailer stabilizes and recovers very quickly.

Here are couple pics of the design. Mine has the Fox shocks. They all have the limit straps inside the coil springs and the red poly bump stops.

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[ntsqd]

The self leveling/adjusting ride height has been done on passenger cars and RV's too. I have just such a switch from a Cadillac. The front drive GMC RV's had a pneumatic switch for their air ride tandem rear suspensions on the earlier coaches. Those were problematic and most owners removed them from the system. I'll bet Cinnabar Engineering has something to replace it. I had thought to use the Cad switch with some Clipper or Skinner solenoid valves on my grandparent's GMC coach, but granddad decided that manually adjusting it wasn't a big deal.

UK, are there no dampers at all, or are those in place performing poorly?

The only force that acts as a 'spring' in a gas charged damper is the charge pressure acting on the area of the shaft since that is the differential in area of the two sides of the piston. Which obviously isn't very large. Charge pressures tend to max out at about 300 psi. So roughly 70 lbs force max from the gas charge of a 5100.

In a Bilstein the valving numbers quoted are Newtons required to move at some set shaft velocity, with rebound quoted first.

Looking at the KK it just struck me (I've seen pics of it before, but never noticed) that the damper is mounted behind the spindle. Increases the motion ratio which makes for better damping when using deflective discs (Fox, Bils, etc.). It may do the same for other damper styles, I've just no info or experience there. One of the issues in F1 with damping is that their total wheel travel is so low that the damper pistons barely move. Here is the reverse, which is much better.