Sphere longevity

[Styria]

I've given the matter of re-gassing the aircells for some while now - alas, as with so many things, I just haven't gotten around to doing so. Supposedly there is a Mechanical Repair shop situated close by to the city that re-gasses Citroen units, but little is known if they are able to repair the Mercedes units. Yes, it would be helpful if some form of rebuilding could be effected.

I take it that the car you are referring to is not the one you bought off Black Hands. If I remember correctly, I did replace all spheres probably ten years ago - at the time when we had the car resprayed for him. It would indeed be interesting to see some photos of any modification work that's been carried out by a previous owner. Regards Styria

 

[Oversize]

I washed MB2 (not Blackhands old car) today & can confirm it has fittings on the back of at least one cell. Unfortunately I ran outta light before I could get any photos.... I'll get them loaded as soon as I have time

 

[Oversize]

What we've long suspected can be done & here's the proof :

Engine bay diagnosis fitting location



Closeups





Main cell nitrogen port



Rear cell nitrogen port



Appologies for the state of the car; it's relatively unchanged since I got it! I'll get around to cleaning it when we have somewhere permanent to call home.... Can anyone identify the fittings??

 

[Oversize]

There's at least 2 places in Melbourne that can re-charge Citroen cells & I've sent them pics to see if the fittings are compatable. I've yet to get further info from the P.O. re the process involved in converting the cells, availability of the fittings & machine shops who can undertake the modifications. More info to follow as it comes to hand.

 

[WGB]

Thankyou - very interesting.

Bill

 

[Styria]

Hmm....indeed Sir. What have you dug up ? Further news would certainly warrant everyone's further attention. I must send you those invoices as a form of encouragement ! Regards Styria

 

[Oversize]

No go re Citroen recharging as they tell me the fittings are not compatable. However it doen't mean an adapted couldn't be manufactured... I'll ask Citroen what fittings they use to keep future conversions simple. I'll also give the P.O. a call today & hopefully get more info.

 

[Tony66_au]

Might I suggest a visit to an Enzed or hose doctor?

I used to have hydraulic fittings made for all sorts of cars by the local Pirtek and Enzed shop because of the high quality of their work and when it comes to couplings they can identify the type and either supply adaptors or similar.

That and they were by far cheaper a lot of the time especially with pressure hoses like Aircon and power steering hoses.

Even brake lines were not a problem although you had to say they were "Clutch" lines *wink wink* because of the whole ADR issue.

 

[Oversize]

Great idea! I'll look for an e-mail address.... I'll need to be carefull though; last time I used a 'hose specialist' based on price, they completely blocked the pipe fittings with solder! It wasn't until the third attempt that they got it right!! So the moral is to always check the work of others (where possible), before re-installing parts.....

 

[Oversize]

I just got onto the PO who tells me he no longer has the equipment to do the conversion, but most machine shops should be able to do it. The sphere must be upside down & heavy grease used on the drill bit to prevent contaminents entering the cell & damaging the diapham. Care must be taken not to push the bit too far into the cell so the diaphram is protected. I guess some type of upside-down drill press would be needed?? Might I add that EXTREME CARE must be taken due to the fact that there may be residual pressure still in the cell!! In fact if anyone converts a new cell, it'll be fully charged & therefore mighty dangerous to start drilling into.... not for the faint hearted! Oil leaking from the new hole means the cell is stuffed.

Apparently many heavy industry accumulators use this type of schrader valve, so they shouldn't be too hard to find. They're either 1/8", or 1/4" BSP parallel thread. Maybe a tapered thread might seal better??

Once the hole is the correct size, it is tapped to the appropriate thread. Apparently there's something called a 'Dowdy' washer that has an O ring underneath. This was used between the threaded end of the fitting & the cell to ensure a gas tight seal. Lock-tight, or thread sealer could also be used as insurance againt leaks. Then a nitrogen charging kit can be used to charge them up...

Interestingly I've seen pictures of Citroen cells converted & the fittings were welded into place. I have no doubt this would damage the diaphrams.

More info to follow mid week regarding pressures & size of fittings etc.

 

[CraigS]

Was there ever any update to this thread ?

 

[Oversize]

Hi Craig, well I didn't get very far as I moved house twice since then & also went on an overseas holiday! I've managed to move all my cars to the same location & steam cleaned them all in the process. That was a few weeks ago. Now, with the on-set of winter & still many boxes to be unpacked, I've been struggling to find time to get into the garage for some serious work. I did drop into a hydraulic service centre a couple of weeks ago & discovered that they could regas them if they knew the size of the fittings & the pressures that were required. From the stampings on the spare cell that I was able to show them (without the re-charge ports), it appeared the pressures were quite high; almost at the upper limit at which nitrogen is normally stored. I'll have to measure the fittings to be able to ID the type, or worst case, remove one from the car.

Is it highly likely that a cell that gone through a bouncy phase has a split diaphram. This is evident by the fact that it occurs suddenly & the large amount of nitrogen suddenly introduced into oil causes the car to bounce. A solid cell may be able to be recharged if it has become firmer over time & hasn't gone through the bouncy stage. This would indicate the nitrogen molecules have slowly passed through the diaphram and dissipated. It is possible that by monitoring the pressures in the cells & keeping them charged, they'll last far longer. It's also possible that pressures could be increased beyond the standard cell, to make the vehicle ride firmer & not so floaty. Of course until I can test all this I'm only guessing, so feel free to comment on my summation.

Does anyone know what pressures where used? I'd heard that there was a heavy duty system available, possibly through AMG. What were the differences over the standard system?

 

[Oversize]

I just had a look at my spare cell & it has stamped on it IMI 524 550 002, Made in Germany, 0.75L, 200 Bar, 05 9 (red dot). Does anyone know if that's max pressure, or set pressure?

 

[Styria]

Hi Mark, thanks for all your time you're putting into this matter. Firstly, let me say that it is good to know that you have now settled into your new home enviroment. I well understand your reference regarding the cold weather, early darkness of the winter season and a reluctance on your part to spend too much time in the garage.......it's not pleasant, is it ? So much nicer in front of the fire with feet up.

It is my understanding that the following pressures apply to the various Air Cells.

6.9 Front (red dot) 75 Ibs./sq.in
6.9 Rears 60 Ibs./sq.in
SLS Rear - 450 - 280 45 lbs./sq.in.

I would imagine that a full hydraulic system on a 560 (very rare) would probably run at 60 lbs. seeing that the engine is just so much lighter than the M100 unit used in the 6.9. Maybe others may be able to share some light on this.

I think in the whole system, somewhere along the line, under certain conditions, there is a pressure reading of 200 lbs./sq.in, but at this stage, I am not sure in what location of the system. From what I understand also, it's now becoming increasingly difficult to ship these Air Cells from the States, therefore if some form of re-gassing is possible, that could well solve apparent future supply issues to some degree. As I have indicated previously, I have old units on hand, but I daresay that any reconditioning process need not necessarily turn out to be saving a lot of money. The alternative, of course, is to go to the dealer but the price.......definitely not cheap.

Also Mark, I took note of the location of the valve on the oil supply hose to the pressure regulator-that seems to defy logic. Any idea on this ? Anyway, I think it'd be a good idea to try and come up with some form of alternative which may well be important in the future. Regards Styria

 

[Oversize]

Hi Styria, thanks for that reply. Note that the pressure stamped on my cell was in Bar, not lbs. Are the pressures you quoted definitely in lbs (which seems odd)? I thought Germany only used the metric scale? Or did you get the specs from the USA?? With the correct pressures on hand I can then have a closer look at the fittings & finally have them regassed; yay!!

Do you know if the cell pressures were different in the AMG suspension, or was it just the strut (valving) that was different? Tx

 

[Styria]

Hi Mark, I certainly won't take you on as far as the Air Cell specs are concerned - not until I get the opportunity to double check, although I reckon you're right on the money with your information. I think I might also have to revise my figures for the steel spring assisted 280s - those cells are smaller again than..no wait, what am I talking about ? I think the specs as I have listed are correct, except for the pounds per square inch equasion.

Talking of longevity and Air Cells - Goldie, my 450SE does have self levelling rear suspension (well, I think so) and those Air Cells, if fitted, are at least ten years old and show no sign of deterioration. Maybe again a case of what we buy today is not as good as stuff bought in the dark ages of yesteryear. Regards Styria

 

[Styria]

Mark, sorry I missed replying to your query regarding the AMG (such as they MAY have been !) struts, I personally do not think that there was much to be gained by having "HEAVY DUTY" struts - in my opinion, pressure that is put on struts on one side due to exuberant cornering already stiffens up the strut under pressure. I have experienced that on a couple of occasions when Gleaming Beauty started to "straighten up' under hard cornering.

As far as the strut internals are concerned, the top of the strut contains a certain number of pressure discs that are held in place by a peened nut. Somehow I have the notion that the manufacturer does not want those discs to be disturbed. There are slots or orifices in the assembly that allows for transfer of oil depending on pressures exerted upon the struts. That is the way I see it.

One could say that thicker oil would definitely alter the handling characteristics of the suspension. I know of one owner that used engine oil in the suspension in his 6.9, without apparent ill effects or deterioration in handling. From a personal viewpoint, that would not appeal to me. Regards Styria

 

[Oversize]

Does anyone know what material was coated on the suspension pipes near the control valve? It was a pea green colour, but unfortunately it doesn't stand up well to the steam cleaner.... I remember Ford used something similar on the high pressure LPG supply pipe between tank & converter on their dedicated systems; it was even a very similar colour! It appeared that Ford used some form of plastic coating (perhaps to protect & insulate), whereas it wouldn't surprise me if the MB pipes were just painted. BTW the car in the pictures is far cleaner now!

 

[Oversize]

So can I get these shipped to Australia, or not?? It seems they're limited to ground shipping only....

http://www.autohausaz.com/search/pr...id=1367603@450SEL&year=1979&cid=27@Suspension System&gid=10928@Self-Leveling Accumulator Sphere/Air Cell

 

[Oversize]

Did we decide which cell was the best for replacements? Is Lemforder the OEM? Or should I just go to MB; being that their units are bigger and will presumably last longer? Adding rechange ports might increase the life of a cell, but once the diaphram is compromised, it's useless.