An update
...And yesterday we did 600km of smooth tarmac only - my newly rebuilt Wilbers leaked again. So it went to get it's 4th rebuild.
My Wilbers warranty is over, no hope to any help from them so I could experiment with it and find the reasons why it's been doing so bad for me.
First of all the overall design of Wilbers - tube+cap design for the pressurized part is maybe not the best way to go.
Cap from beneath.
We found some variance in the cap radius (not a perfect circle). Meaning it will make the tube slightly oval from one end and - if the shock piston hits the upper part of the tube it may have "squeeze-effect" for the moving details that drag against the tube wall.
The cap didn't "teeth" well with the tube too. I.e. in one side you see the contact marks:
And on the other side of the circle it was hardly noticable:
This could also be un-evenly cut tube from one end and in theory shouldn't affect the overall performance or reliability of the shock, but enough to notice "bad manners" on manufacturing the details.
I let a new cap to be machined to have more precision:
The new aluminium is considerably stronger than the original alu that was relatively soft and thus probably more prone to go out of shape and have "teething" problems. Hopefully the new cap sorts out the ovality problem for the tube.
The emulsion-type shock body design concept in comparison: Öhlins pressurized part in one solid chassis IMHO making it considerably more stable solution compared to Wilber's separate tube+cap solution:
From where I can see why Wilbers was cheaper than Öhlins for my bike - I reckon it's noticeably cheaper to CNC-machine small more simple cap to combine with (cheapish?) tube instead to CNC out a whole big complicated upper part like Öhlins does.
And indeed my Wilbers leaked from between the cap. It is thread-glued on the tube making it prone to twist or leak - i.e. if you need to adjust the spring preload you need a supporting spot, which is normally the top cap to hold the shock still while you adjust the preload.
It also weirdly leaked from inside the piston rod (small diameter pipe), which I can fine no other reason than a bad inner-seal (small o-ring)?
Anyways, altough with some sense of humor as seen on some pics, this thread IS NOT about making look Wilbers bad. It is just to argument and let the more suspension-experienced guys give their word about my (non-specialist but hopefully logically-put) observations.
So tech-gurus, give us your input!
I've now put brand new Öhlins on, let's see how it does under our abuse.
Ride safe, Margus