C5 ride

[aneesh84]

Sorry I hadnt read to the end of the Forum. This was what pas posted latest:

Citroën now subcontracts to IFHS the manufacture of its spheres (Citroën no longer manufactures its spheres) and apparently those of the Eurorepar brand are no longer multi-layered.

Multilayer membrane spheres are the subject of a Citroën patent and can therefore only be sold by Citroën.

[white exec]

Thank you for posting the link to that Caradisiac forum Aneesh.
Interesting to read that recent information about Citroen's, Eurorepar's and IFHS spheres.

[aneesh84]

Like with any other information found in forums, it is not from an authorative source, so merely speculation by users. Infact from what I understood (my french is terrible) that they tested Eurorepar spheres from 2 years ago and found them to be multicouche since no loss in pressure, but due to recent changes in part numbers they removed the advise of asking to buy Eurorepar spheres as a precaution since they are not sure if they are still selling Multicouche spheres. It may be very well that the sphere quality of Eurorepar is still multicouche, and of same quality (since they make a 10 year life claim for C5 spheres on their website)

With time we will have more clarity.

[aneesh84]

Another french forum posted some pictures of the EUROREPAR Sphere membrane made by IFHS:

https://www.planete-citroen.com/forum/s ... /page5#124

It was reported as not being multilayer. Citroen spheres are also now reported to be made by IFHS which I would assume to have the multilayer membranes.

However the black membrane in EUROREPAR spheres seem to be different from the yellowish IFHS membranes posted in earlier posts here: viewtopic.php?t=55077&start=15

[411514]

Multilayer membrane spheres are the subject of a Citroën patent and can therefore only be sold by Citroën.

If Citroen ever did have a patent for the multi-layer membrane it'd be gone by now - the maximum term being 20 years. The C5 was launched March 2001, so any patent would need to have been filed before then, and would have expired no later than March 2021. But just from a brief look another Citroen patent US5992832A has a priority date of 1995, and mentions multilayer membranes. So assuming '832A was the first patent to disclose it, which seems unlikely, no patent could have lasted beyond 2015.

[white exec]

Patented formulations and products can be tweaked so as to enable fresh patents to be taken out.
At some point, the cost of doing this becomes not worth it, so they slip.

[aneesh84]

Multilayer membrane spheres are the subject of a Citroën patent and can therefore only be sold by Citroën.

If Citroen ever did have a patent for the multi-layer membrane it'd be gone by now - the maximum term being 20 years. The C5 was launched March 2001, so any patent would need to have been filed before then, and would have expired no later than March 2021. But just from a brief look another Citroen patent US5992832A has a priority date of 1995, and mentions multilayer membranes. So assuming '832A was the first patent to disclose it, which seems unlikely, no patent could have lasted beyond 2015.

I believe you are right. The patent expired in 2017.

https://patents.google.com/patent/EP0777065B1/nl

https://patents.google.com/patent/FR2772099A1/en

However, since peogeot has already a partnership with IFHS to produce spheres for both Eurorepar and Citroen Brands, it would be Citroen dictating to IFHS which membrane to put and in which sphere. Also Membrane technology may have evolved so it may not be easy to cut open a sphere and judge the nitrogen escape rate (a function of membrane porousity) simply by the thickness of the membrane. Only periodic pressure loss tests will prove it. Previously Eurorepar C5 spheres (Pre IFHS) were reported to have the same membrane as citroen spheres, so it would be bad for Peogeot to downgrade Eurorepar quality (a brand they are trying to promote) without warning to consumers.

Due to the expired patent, it should be legally fine for any third party to make multilayer or long lasting membranes, but the issue is, that due to reduced number of older hydropneumatic C5s on road, the demand is always decreasing. So do third parties even consider it a product worth making much investment on! Also a longer life sphere would mean only a one time sale, further reducing demand!

[411514]

Patented formulations and products can be tweaked so as to enable fresh patents to be taken out.
At some point, the cost of doing this becomes not worth it, so they slip.

That's true, but in that situation it's only the tweak that has the extended patent protection. Fundamentally, the multi-layer spheres were disclosed at least as early as March 2001 (probably much earlier), and so the multilayer concept itself cannot have patent protection.

[aneesh84]

Unless there's something about a C5 mk2 I don't appreciate, I don't understand why the ride should be inherently so much worse.

Non-hydractive models normally provide a very good ride, as the four wheel spheres are chosen to be softer than their hydractive counterparts.

Aggravating factors that won't help (apart from the very slight volume reduction of the saucer spheres) are incorrectly-spec'd aftermarket spheres, low gas pressure, or even slightly over-inflated tyres, maybe with stiff side-walls.

Citroen had a long history of non-HA models riding extremely comfortably - CX, BX, XM and Xantia - so I'm puzzled by this. There has to be a solution.

Dropping tyre pressure by 0.2 bar (no more, and check the pressure gauge is accurate) is an easy experiment, to see if ride improves. I've found that just 0.15 bar (2.2 psi) can make a difference on poor roads.

Got 4 new standard spheres, and I must admit the ride has significantly improved! Completely satisfied! I even compared with my friend's C5 X7 H3+, and found my H3 to be less wallowy and more stable but soft enough on big bumps and country roads. Only on extemely broken roads, i found the H3+ better, but such bad roads are not so common. Maybe the comfort spheres could improve things but i am afraid the ride might get underdamped.

[falling-out-with-my-car]

on my Mk2 C5 2007, hatchback facelift exclusive, the tyre pressure sensors screamed at me if the tyre pressures stooped below 42 psi , fortunately as the car is earlier than 2015 it was perfectly legal to have them removed , I now run the tyres at 34 psi rear and 32 psi front (car unloaded) and the longevity of the tyres has increased immensely and the ride is so much better than it was.

[Peter.N.]

Certainly it will improve the ride, I have been known to run mine slightly below the recommended pressure for that reason.

Peter

[aneesh84]

on my Mk2 C5 2007, hatchback facelift exclusive, the tyre pressure sensors screamed at me if the tyre pressures stooped below 42 psi , fortunately as the car is earlier than 2015 it was perfectly legal to have them removed , I now run the tyres at 34 psi rear and 32 psi front (car unloaded) and the longevity of the tyres has increased immensely and the ride is so much better than it was.

why do you run the rear at a higher pressure than fronts? shouldn't it be the opposite?

[white exec]

That is indeed an odd arrangement.

[Dormouse]

I have found that different makes of tyres respond differently to tyre pressures. I start off at the recommended pressures and then adjust (sometimes up) until I get the tread wear pattern/comfort I am looking for. Usually it is only a few psi, if anything. My camper is the perfect example of extremes. The book says 57 psi but I run them at 44 psi - the important bit is contact patch/tread wear and side wall flex under load. Too hard and the ride is firm and the centre tread wears out first. Too soft and contact patch/side wall flex is compromised. Most vehicles spend 99% of their time in the same load configuration and are used on the same journeys so once they are set they stay there. I must be unusual in that I reset my tyre pressures for different types of journeys but I know people who never check their tyres and they are still in one piece, so is it all worth it? Handbooks will often give the same pressures even for different tyre sizes and types and, occasionally, gives pressures for fully laden or high speed driving but they never specify make and construction.

[GiveMeABreak]

I need to update the info for the camper as I have just about finished the next stage of fitting out and have now done enough miles to report that I now do 44 psi front and 48 psi rear. I have added batteries and more insulation, panels, fittings etc and the rear axle weight has increased by 250 kg. Pint Pot is an ever evolving project and the figures first quoted were when she was little more than a bare van with some insulation and linings. Things like rear step/towbar, rear door spare wheel carrier and twin leisure batteries have all added more weight to the rear hence the new figures I have settled for.