For suspension I loved the Citroen hydropneumatic system which also powered the steering and brakes. It got a bad reputation because the steel hydraulic pipes rusted and were a pain to fix OR the body rusted and the pipes gut in the way for repairs.
The Citroen C5 and C6 iused the system. There are not many C6 about so prices are holding up. But all are diesels and they have so many early noughties electronics they are likely to cost a fortune when things break.
I always liked the look of the DS's. Way, way back we had one in the workshop which needed one of those brake pipes renewed - the boss gave me the job. Luckily I was running around in a Dyane at that time and had just done some of it's brake pipes so I knew that they were 3.5 mm diameter pipes (compared with the 3/16 inch (4.75 mm) stuff used on nearly everything else.
Because "everything" was hydraulically powered there were pipes running all over the place - quite daunting at first glance! I also knew that the flares were very different and needed different flaring tools to ours and used "O" ring seals too! My boss looked quite surprised (and impressed) when I came into his office/showroom and asked where I was to go to get the stuff needed to do the job. Did my "cred" a lot of good! Oh, and the fluid was mineral too not mixable with the stuff we stocked in our stores! - Called LHM if I remember? He was even more impressed when I told him I had a contact who would flare the ends on the pipes for us.
Citroen were very "different" cars to work on and many of my workmates would do almost anything to avoid being allocated one to work on. I remember being very surprised when doing the pipes on the Dyane to find they don't use flex brake hoses! Instead the pipe itself is wound round 3 or 4 times, in a coil - bit like a closed coil spring - inside the hollow pivot point of the suspension arm so the coil slightly tightens or loosens as the suspension goes up and down. A bit like how they used to coil metal fuel line on really old cars between the chassis and engine to minimize the chance of fracture. This was only on rear brakes of course because the fronts were mounted inboard on the gearbox so didn't have to accommodate the steering.
As you may know, but some may not, because the suspension on the DS was maintained by fluid pressure it would slowly sink to the ground overnight as the fluid leaked back to the reservoir (the quicker it settled the more problematic the suspension might be) When you returned to the car in the morning it would be virtually resting with it's floor on the road! Very alarming if you didn't know this was normal! On starting the engine the engine driven pump would cause the car to rise up to it's normal height as the pressure was restored. The fun bit was that there was a lever between the front seats which allowed you to almost double the height of the suspension for going over rough ground so, if you were so inclined, you could sit at traffic lights amusing yourself, and others around you, by making the car go up and down - it went up slowly but down quite impressively fast!
This "high" setting was used when a wheel needed to be changed (maybe because of a puncture). You simply set the lever to "high" and, once the car was at full height, put a stand under the jacking point and put the lever back to "low". The suspension would go down until the chassis contacted the stand and then the further contraction of the suspension lifted the wheel off the road. So no need of a conventional jack! I think they also advertised that you could drive around with one back wheel missing? But I never really saw the point of that?
A very good friend of mine, another mechanic so he should have known better, bought a cheap, well used, C5 estate but I never actually got a ride in it as it was always being "mended"!
