progressive bumpstop acting as airspring/shock absorber/bumpstop all-in-one
Here is the link to my build using a single link air bag solution with a pan hard bar. It works beautifully, can be adjusted for height/load easily and is relatively cheap to build.
http://www.expeditionportal.com/forum/threads/77927-quot-Old-Man-s-Toy-quot-offroad-teardrop-trailer
Post #2 shows pix.
View attachment 375431
On my squareback trailer, having had spring or hanger breakage before, I made my own "airbag substitute" to use in-between my axle and frame.
Copied from a previous post:
...but from what I have seen in the past if you remove too many springs..
that the springs often break where there is no support underneath them
think of them as a foundation that flattens out when under load & flexing, when they collapse the one underneath supports it
if you remove one long one & leave too short of a one, the longer spring basically tries to flex down past the supporting one & breaks at the fulcrum point....
The quote above was the focal point of my recent trailer suspension re-build (its not a M101CDN, though my trailer is rather heavy at 1600-1800 lbs-trying new configurations-; maybe comparing apples to oranges?). Since I feared having my springs flatten-out, if over-flexed, breaking the spring (broke one on my car-hauler), and/or causing a hanger to tear off the frame at that point (happened once on my little trailer, spurring my alternative approach), I put a bump stop made to stop those mishaps from happening again. However, I wanted to have a
progressive response from the bump stop, before the limit of travel is reached. The axle (on my "being modified for soft-roading" trailer) has only 1.125" of travel from normal ride height to suspension at full droop, so I thought that the use of standard shock absorbers would not be beneficial, and opted for a non-standard approach: a progressive bump stop to serve both functions. It acts like a hollow air spring (like a Timbren Aeon $$$, Sumo, or like found on the old Ford Model A shocks -"balls"-, and similar on several older European models). I modified it to fit, and softened its "rate" (by removing the hard/stiff top). I had experience using poly bump stops on several of my trucks, and thought that the Daystar "progressive" would need little mods to fill my needs. I've tested it, in actual on-road use, and "simulated off-road" terrain (pot-holes, speedbumps, whoop-de-doos), and it does well. I can even soften the rate more, if I choose to. If you, the OP, want to use "soft-er" springs on your M101CDN, but wish to avoid the consequences of over-flexing under over-loading or rough impact, consider this approach (or similar).
It works well on the road, and on dirt roads, but I haven't been into any real bad topography (no 4wd yet), so I haven't needed to see if I need to soften the compression rate, by cutting through the center filament (will compress more-and-quicker, and increase travel somewhat).
