Different brands of Accumulators

[wbrian63]

Something to consider when purchasing spheres. They have a shelf life. Some brands (I believe the OEM versions do) have a manufactured date stamped on the housing.

It is my opinion that they actually last longer installed on a car than sitting on a shelf.

Consider the design. A sealed container with a rubber (or some flexible material) separating atmosphere from some very high pressure nitrogen. What causes these items to fail over time aside from the occasional diaphragm rupture, is gas migration through the diaphragm.

Sitting on the shelf, the pressure opposing the nitrogen is 14.7psi.

Installed properly in a car, the opposing pressure is exactly the same as the nitrogen, plus the opposing object is a fluid, not another gas, further slowing the migration.

This the primary reason I never by accumulators off eBay. When the prices are cheap, it's usually because the products are really old.

I can get a full set of OEM spheres from the Classic Center for about a grand +/-. I can get Febi (I believe) for around $700 for a full set, if memory serves.

I need to replace all of the spheres on #521. If I can ever get it out of the shed...

At some point, I want to take a sphere and figure out what it would take to recharge them. The orignal design from Citroen, if I recall, has spheres that can be recharged. The biggest issue I beleive would be figuring out how to get a hole drilled in one without creating a projectile of drill shavings.

These units are manufactured in a pressurized chamber. The front, to which the diaphragm is attached and the rear are placed in the chamber, where all the air is removed and nitrogen is added at the desired final pressure. Then the halves are brought together and welded. Nitrogen is recovered and the result is nice high-pressure gas inside the sphere.

Regards

[MB_Mike]

Good point about be careful when buying from Ebay. There is a guy selling Lemforders for around $725 IIRC. He says they are all new stock but then offered me a better price outside of the'bay. Not saying he isn't legit but that may severly reduce my chances of a refund in the event the product isn't what he says it is or by chance I get a defective one...

Anyway, I guess I am bringing all this up because after parting out the W126 500SEL I had with this system, I developed a new respect for the engineering and what it represents for MB. So I found and bought another W126 560SEL with the hydropneumatic suspension and it needs accumulators in a BAAAAAD way. If you ever saw one of those bouncing low-riders, that is what this thing does with no exaggeration (but then again look who I am telling, a bunch of 6.9 owners, so you know).