Multicouche spheres, How long do they last?

[Jan-hendrik]

In the following thread the topic of these spheres came up:
http://club-xm.com/forum/index.php?showtopic=5106

To expand on that I think I could say that the life of these spheres or any other spheres cannot be decided by how long they have been on the car or what distance they have covered.

When I bought my current XM in March 2007 with 36658 km on the odometer, all spheres were replaced with new ones and I got to keep the 'old' ones, which were really not that old but had been fitted not too long prior to the purchase.

In recent months I thought I began to notice the front suspension becoming a little harsher, although pushing down on the front of the car did not confirm that (engine running and all that of course). On this beautiful late Saturday afternoon (sunny, 35 degrees) I suddenly decided to try something. I de-pressurised the system and replaced in no time at all the front suspension spheres, the dimpled ones that are supposed to last, well, not forever, but longer than the urepan ones.
The replacement spheres being the ones I had kept in the garage for more than 4 years. Test drove the car and instantly noticed the difference. Less bumpiness and noise from the front train, smoother springing and damping. I drove around the next day, Sunday too and confirmed it was not my imagination.

I have no way to measure pressures of these spheres and the dealer does not have a test stand either. But I noticed something that might be significant: on the right hand sphere there was a tiny piece of rubber-like material lodged in the discs of the damper (yeah, I should have taken a picture . It seems likely that that sphere had failed, a membrane damaged. More shredded rubber may have gotten into the system and I can only hope this will end up in the filters. But I don't think I need to worry too much as the particle I found was really small and it was stuck. For something to get through the damper it has to be really tiny.

What is there to learn?
Well, for me I can conclude that sphere life span depends a lot on the road abuse they get to endure and the climate. The roads in the suburbs I drive here aren't that great (high ways and motor ways are OK) and the suspension gets quite a bit of hammering contributing to an early demise of the spheres - I think.
On the other hand I did the first replacement of all the spheres on my 1995 XM, which I had bought new, 5 years after buying it which produced only a marginal improvement. Hmm
Anyway, I tell myself, don't put too much faith in the quality, reliability, longevity of hydraulic spheres. Replace them at the start of any trouble shooting.

BTW, the set of spheres I got delivered with the car also had 4 comfort spheres that were like new, as they had been fitted just to please a possible buyer who reneged on the deal. That kind of spheres totally defeats the hydractive qualities of the vehicle and I was happy to sell them on an internet auction!

[Peter.N.]

Can't agree with you on the comfort spheres I'm afraid, the softer the better as far as I'm concerned, I would very much like it to ride like a DS - I don't care if it leans on corners, as long as I can't feel the bumps.

My GSF spheres usually last about 60,000 miles but they don't get a lot of hard uses except for driving in and out of our place which involves about 1km of very rough forest track.

Having said that, they used to last 60k when I was doing about 30k a year but it takes me two or three years to do that now so I expect time will have an effect.

We don't hear much about Japan now. what's the situation with the radiation leaks?

Peter

[Jan-hendrik]

QUOTE

We don't hear much about Japan now. what's the situation with the radiation leaks?

Forgive me for not wishing to go into this. It depresses me.

[Peter.N.]

Ah right. I'm sorry.

Peter