aerodynamica wrote:Cheers mandrake it is looking like the rears are wrong after all. The previous owner supplied an invoice for the spheres being ' checked', and 5 regassed, one replaced (rear centre) - it wasn't a cheap bill but they seem to have screwed up. Haha, apparently it was the ' young guy'..
These days when you can buy decent IHFS spheres for a reasonable price there isn't much point to regassing... When I lived in NZ where spheres were hideously expensive it was worthwhile!
I put a full new set of spheres on the V6 when I got it in 2014, the rear ones were completely punctured... They're coming up on two years old in another month or so. I'd say that the ride is slightly firmer than it was when I first put them on but not much, so they seem to be lasting well.
Not sure I agree the fitment of a damped sphere in the centre negates the hydractive as its damper is stronger than those fitted in the firmness regulator so for independent left or right. Wheel movements it'll serve to damp that volume of fluid each (discounting the corner damper effects that is) it is where both wheels move together that the damping would be greatly increased.
I'm not saying that it won't work, just that anything that you do to stiffen the centre sphere is only going to reduce the difference between soft and hard modes, thus somewhat neutering its ability to change the handling/ride characteristic under computer control.
I played around with the tuning of my first HA2 Xantia a lot and found that I kept coming back to pretty much stock. About the only modification that I preferred was reducing the bypass holes in the damper valves in the "firmness regulator" slightly - I reduced them from 1.1mm to 0.9mm which took away the slight floatiness that car had but still left the ride very smooth and stable.
I wouldn't bother trying to do that modification on the V6 I have now though - with UK road salt the pipe fittings etc are rusty enough that I'd rather not touch them, whereas the one in NZ everything was rust free and like new underneath!
By the way, don't spend too much time trying to tune the centre sphere or damper until you have the correct strut spheres on, because the two interact in a somewhat counter intuitive way in soft mode. It turns out that when the strut spheres get low in gas and become stiffer, this makes the hard mode stiffer (as you would expect) but actually reduces the damping in the soft mode causing the soft mode to become a bit wallowy over large undulations and seem like it doesn't have enough damping. Regassing/replacing the strut spheres in this situation actually restores normal damping in soft mode!
I think the reason for this is due to the two parallel paths that the oil can flow when you hit a bump in soft mode - it can either go into the strut sphere, or it can go into the centre sphere or in reality a bit of both. The strut spheres have small bypass holes and stiff leaf valves so they will not pass any significant flow for gentle movements, forcing all that flow into the centre sphere through the much softer damper valves in the firmness regulator.
When everything is balanced properly if you hit a large undulation in the road a good part of the resultant oil flow goes in to the strut sphere and then is "trapped" there and only released very slowly by the stiff damper valve - so the rebound damping for a large undulation is quite strong. A gentle movement only passes into the centre sphere so only has soft damping for the rebound. Effectively HA2 in soft mode is a multi-stage variable damping system where the degree of damping on the rebound depends on the nature of the initial movement/impact, (which affects what proportion of the oil goes in/out of the strut spheres vs the centre sphere) rather than having a fixed tuning.
If the strut spheres are low in gas it forces even large undulations to be absorbed by the centre sphere thus the rebound is not as well damped and the car feels like it is lacking in damping. I've seen this on two cars now where a good centre sphere but relatively flat strut spheres caused the soft mode to seem quite wallowy. As soon as the strut sphere were replaced the soft mode damping actually firmed up.
In your case you have the wrong damper valves in the strut spheres though, which complicates things even more. If it were me I'd throw on two new strut spheres and put the original centre sphere back in place and evaluate it again to see if you like the result and go from there.
but would anyone know if it's the temp sensor or an earth or somthing that is most suspect? Also, where is the temp sensor located? Couldn't see any obvious sign of it on the mirrors. 
