There is a great difference in drive comfort and quality if you have hydrocompensator on rear axle.

I have on my w108 rear axle which bought 14 years ago and driving car only summer time and nothing happened. But as a disadvantage, You can't load car and trunk at the same time full like spring. As the system works on hydraulic fluid over high pressure as a damping medium(As I remember correctly around 75 bar pressurized Nitrogen filled in), in the case of falling in ditches on bad roads when car fully load, high pressure nitrogen can destroy piston oil ring and gets out from hydromat upper cap rubber manchette. Finally gets defective and car rear drops down as the pressure decrement to 0)

In the past I worked on this hydromats as a curiosity to check what exist inside) and open one which I bought from dismantler about 20 years ago. Hydrocompensator was defective and even I can push piston with my hand till almost half( normall you can't move piston even mm by hand) so losen upper cap and piston flew away and hit the concete wall and destory it. As it's written on outer chamber that never open even defective)) I repaired oil gaskets and replaced oil rings on piston and check the condition of 2 rubber chambers, filled with thich suspension fluid and pick it up back.However, the problem here is not repairing the compensator. For me, problem is how to and from where to fill pressurized Nitrogen into compensator. I guess, Boge has special filling aparatus to fill from 2 star screws which are on the outer chamber as well or its filled in already pressurized medium.

Because if you use special nozzle to fill compensator with high pressurized gas, here its over 70 bar Im sure, at the time filling is completed how you can close seal it? Because it gas will escape to air. This is the part that I still don't understand, if I find solution it's not so mcuh difficult to repair I guess, unless in rubber chamber inside are torn? Which is imposible to find anywhere. I think this is the criterion that After inspection Sachs says after inspection that Hydromat can't be repaired.

Sorry for my detailed maybe boring story just expained my experience with this weird useful device)

Regards,

Kutluhan