My mates 2cv has very soft suspension. When you rock up and down (back and front) it is too easy and soft. And too much roll on corners and bends. It sits on a 5 year old galvo chass. I suspect it is something to do with with the shocks or suspension can. Ride height seems correct. Any ideas?

Check that the rear shock absorbers have been fitted the right way up.

sorry forgot to say.............when rocking up and down when car is stationary you can hear a low pitch non metalic noise from underneath

hardy,
the groaning sound could be dry suspension canisters or a damper.
There's no substitute for getting underneath to check, though...

How much gap is there between the bump stops on the sides of the chassis and the bracket on the front arms?
If that's more than the specified 3mm to 6mm, there will be excessive roll.

Is the suspension soft on every corner of the vehicle, or maybe only on a diagonal?
The latter would suggest that the corner weights are incorrect, which can be checked by 'tripoding' the car.
You need a high lift jack and a spreader beam, which are used to lift one end of the car at a time, with the jack positioned as close to the front or rear of the car as possible and centrally on the beam.
Compare the heights across the axle which is on the ground and the side which is low is carrying less of the weight than it should...

Of course, if the dampers are fitted incorrectly, worn out or 'Brand X' all bets are off...

ken