Hi, I bought my autobiography 3.0 sdv6 about 5/6 months ago and too date (I shouldn’t say this) has been ok with only a few minor glitches which is to be expected with the green oval.
About a month ago a dull clonk started in the centre rear of the car when the body changed direction so I hoped it was the drop link a nice easy fix, wrong it’s the active anti roll bar. I disconnected one of the drop links and there is about 1-2 cm of movement before the other end takes up tension (slop I would say) and if you pull up and down on the end you can replicate the donk noise you can hear inside the car.
My questions are, has anyone experienced this and what was their cure? Is the hydraulic side of it only for the off road mode to split the bar in the middle? Inside the unit on the bar is it a mechanical link (which could have worn to give the slop)? do the hydraulics force one side up when you corner to keep the car level? Has anyone had one of these stripped to see how they work inside?
Sorry for all the questions but these bars are so expensive I’m trying to cover all bases before parting with cash and trying to fit it.
Thanks for any help or advice Gaz.

The bar is basically a hydraulic cylinder with a spiral groove around the piston part. As fluid is added/removed the spiral groove causes a torque to be applied. The bar is active during driving and resists roll by applying a counter torque to the direction of the roll moment. In off road conditions (basically at low speed), the bar acts as if it is decoupled which gives maximum articulation (and suppleness on road at low speed). If side angles exceed a certain figure, the bar will be locked up to reduce roll and thus reduce the chance of a roll over.

The bar doesn't lift a wheel when off road - the air suspension causes the articulation by cross linking the airbags and thus allowing air to move from one side to the other.

Edit: I see you cross posted and that Col has given you a link to a manual excerpt detailing the bar's internals. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

Thanks for the explanation makes sense how it works, I just can’t work out how it would get play in it and what could be physically worn inside to make it clonk. I will have a look at the diagram on the other post, I wasn’t sure which to post this question on, thanks again.