View Inside a Suspension Sphere

G4EIY · Unread post by **G4EIY** » 03 Feb 2006, 21:21

Hi Folks,

At long last I have cut open a Sphere...

I have cut off the screwed section, and I use this to plug the hole in the rear arm hydraulic rams to prevent crud from entering, when cleaning, ready for the new sphere.

mpr1956 · Unread post by **mpr1956** » 03 Feb 2006, 21:44

I'll wager that took some hacksawing!! These spheres are pretty substantial items aren't they ?

Unread post by **Peter.N.** » 03 Feb 2006, 22:07

Mmm! interesting, are you reckoning on reconditioning it?

bxbodger · Unread post by **bxbodger** » 04 Feb 2006, 00:10

Gods teeth!!!!

You must have been bored.............what were you expecting? A pot of gold??

Someone will probably now tell you off for doing a naughty and dangerous thing.....

Mandrake · Unread post by **Mandrake** » 04 Feb 2006, 02:21

Sadly, the most interesting part of the sphere - the diaphram, and what it looks like, seems to have been destroyed by cutting it in half

Was that an accumulator or a suspension sphere ?

Regards,
Simon

Clogzz · Unread post by **Clogzz** » 04 Feb 2006, 10:57

mpr1956 wrote:I'll wager that took some hacksawing!!

bxbodger wrote:You must have been bored...

Ideal job for an inquisitive mind on a ‘cool’ winter’s day.

G4EIY · Unread post by **G4EIY** » 04 Feb 2006, 12:33

Hi Folks,

Just to expand on the queries a little:

Yes, I cut off the interesting threaded bit using a hacksaw, and it was on a very cold day in the garage, and it did keep me warm..

Cutting the remainder in half I used an angle grinder...

I was suprised to see that the membane was in fact translucent, but this was a dead one and the diaphragm was split, so no LHM or pressure...

The sphere was in fact a suspension one, but i don't want to cut the interesting threaded bit in half, as I had a good use for it, as my original post...

I did try to remove the damper disks etc from the threaded section, but this was well and truly fixed, and although I gave it some welly, it just would not budge...

Any one managed to do this ?...

Cheers
Brian

Clogzz · Unread post by **Clogzz** » 04 Feb 2006, 13:18

Translucent membrane, that's the 'multilayer' sphere from the front suspension, with 3 dimples around the plug.
Worth knowing that they can split.
Have seen opened ones at my mechanic's shed, and he did the lot with an angle grinder.
The clear membranes looked perfectly good, but the pressure had still escaped.
Many of the multilayer spheres are well over 10 years old.

bxbodger · Unread post by **bxbodger** » 04 Feb 2006, 16:17

The clear membranes looked perfectly good, but the pressure had still escaped.

What are they made of?

BL Hydragas ones are, I believe, neoprene, and they retain sphere pressure more or less indefinately-for decades.

They are, in fact, an integral part of the suspension unit and can't be changed like a Citroen one can without having to change the whole unit.

The Citroen membranes must be made of something different for them to go flat as quickly as they do.

Clogzz · Unread post by **Clogzz** » 04 Feb 2006, 16:43

Story from Pleiades:

The sphere is not laminated but the diaphragm is.
Earlier diaphragms were made from polyurethane.
This was an excellent material being resistant to both mineral fluids and low temperatures.
However, it does permit the passage of nitrogen molecules (molecular diffusion).
In the laminated diaphragm, a thin layer (about .3mm) of polythene is sandwiched between two layers of polyurethane.
The polythene is almost impermeable to nitrogen molecules and therefore does not lose pressure to any degree due to diffusion.
Snag is that in cold climates it can crack thus cutting the polyurethane and dumping the gas.
Citroen overcame this problem on the C5 by changing the sphere shape to oblate spheroid thus reducing the degree of diaphragm flex.

My uncle in Belgium has always had Austins only, including 2 Maxis, and there never were suspension problems.
They were comfy and good fun to drive, especially centring the steering with the accelerator.

Mandrake · Unread post by **Mandrake** » 04 Feb 2006, 19:29

G4EIY wrote:I did try to remove the damper disks etc from the threaded section, but this was well and truly fixed, and although I gave it some welly, it just would not budge...

Any one managed to do this ?...

The damper disc unit is held in purely by an interference fit, and according to my Dad it is possible to remove it (with considerable difficulty) although I didn't ask how.

Refitting is probably done by freezing the damper unit, heating the sphere base and pressing it in with a press...

Regards,
Simon

Mandrake · Unread post by **Mandrake** » 04 Feb 2006, 19:33

Clogzz wrote:Translucent membrane, that's the 'multilayer' sphere from the front suspension, with 3 dimples around the plug.
Worth knowing that they can split.

More than that, apparently they split a lot more easily than the standard diaphrams, when the gas pressure gets low and the diaphram is forced to start folding back on itself...

It's only the fact that they lose pressure so slowly that makes them long lasting. Once they do lose a lot of pressure they crack easily, which I guess is why Citroen have done everything possible to prevent people regassing them...once they get to the point where they really need regassing, the diaphram damage is already done...

Regards,
Simon

AndersDK · Unread post by **AndersDK** » 04 Feb 2006, 20:53

Simon -

Try ask your old man if he remembers the DS/ID spheres. Here the damper unit was fitted as a threaded unit ...
Would be nonsense to try remove it as new spheres are very cheap - and the vast selection of sphere types makes it possible to choose any modified suspension damping you want - at your own risc.

Unread post by **Peter.N.** » 04 Feb 2006, 22:43

I think that the BMC 'hydrolastic' suspension units used a considerably lower pressure than the Citroen spheres, due to there having a larger surface area. That must have been something to do with their longer life. Yes, I really am that old!

bxbodger · Unread post by **bxbodger** » 04 Feb 2006, 23:09

To clear up any confusion for our younger readers,BMC Hydrolastic was rubber sprung- no gas, as used on the 1100/1300, Maxi, Landcrab, wet subframed minis, etc, whereas BL Hydragas was nitrogen sprung, as in a Citroen sphere,and introduced on the Allegro, used on the Princess to wonderful effect, and still in use on the MG-F.

Its strange how the Citroen system is still held up as a paragon of advanced technology, whereas Alex Moulton's hydro systems are more or less forgotten!!