Martin at Pleiades very kindly lent me a sphere tester and on Wednesday I spent a happy hour or so testing my stock of (mostly) Activa second-hand spheres. I was happy to find all had a bit of residual pressure in them and even happier to find that the stock yielded a good set of front corner spheres and a good front Hydractive centre sphere. Also a couple of rear Hydractives that were 5 bars down
All the rest are not totally flat and are therefore regassing candidates.
The good ones were all the 3-layer ones with the three dimples. They do hold their pressure well it seems although Martin tells me they tend to keep good pressure for a long time and then fail suddenly.
I also pulled off the temporray spheres I'd fitted to my Activa and found although the rear felt OK (well damped) but rather hard, the rear corners were 50% down at 15 bars although the Hydractive centre was only down by 5 bars.
I'm on a bit of a quest with spheres now and yesterday, in a flash of wanting to know an answer to a question that had bothered me for some time, I sported out and bought a set of new Amtex normal Hydractive rear corners and Hydractive centre spheres. These are similar to genuine Activa items but do differ slightly in pressures and damper hole sizes.
I fitted them and was pleasantly surprised to find they work really quite well. The rear is now well damped and generally feels good. Not too soft or hard really. The main thing is the damping is spot-on as a spin around my Activa test track nicely proved
My test track is a circular run of lightly used back roads full of tight bends, poor surfaces and dips, some hidden.
Speaking of hidden dips...
In an earlier post, I pondered why the Hydractive Centre Spheres retain so much pressure. Today I worked out why. Basically, when the main hydraulic system is depressurised, the pressure in the Hydractive Centre Sphere will press on a piston in the Hydractive block and effectively shut the sphere off from the main circuit as it does when the electrovalve is switched to hard mode. Even operating the electrovalve to soft mode won't release the pressure as there is no main system pressure to shuttle the electrovalve piston across. I now see why MK2 Xantias have bleed valves on the Hydractive blocks. I don't mind undoing a sphere under pressure (and it's easy with a Pleiades tool) but it is messy
Mind you, LHM is a great hair conditioner though. I got a load in my hair the other day and when I washed it, my hair felt all silky and smooth!!!