Can you rebuild 6.9 nitrogen spheres?

[Emmerich]

I just recently heard that the nitrogen spheres on a 6.9 can be rebuilt. Anybody ever heard of that? I have owned a 6.9 for 5 years and never heard that as an option. I know the hydraulic struts can be rebuilt, but the spheres are a new one for me.

Fred

[gerryvz]

No, the spheres cannot be rebuilt. There is a membrane internally that separates the fluid from the nitrogen charge. This membrane tears, which allows the nitrogen (which compresses and expands, providing the "springing" effect) to escape into the hydraulic fluid.

It would be futile anyway to do this, as the nitrogen spheres are relative inexpensive anyway. The time and energy to rebuild one wouldn't be cost effective given the price of the spheres. They can be had online for under $175 apiece (fronts, red) and $140 (rears, blue).

The prices have gone up significantly in the past 1-2 years, however.

The struts, as you mention, are rebuildable with new internal sealing rings. I am not too aware of too many people actually doing this, but the last time I checked on prices for struts they were $760 APIECE, and this was 2-3 years ago. I'll be they are pushing $1,000 a pop nowadays. Fortunately they don't go bad (leak) too often. (for reference, the rear hydropneumatic struts for the 1992-1994 500E run $250-300 each).

Cheers,
Gerry

[Emmerich]

Gerry, I am with you on this, one of the Aussie M100 guys swears the spheres are rebuildable. Being an engineer, I was aware this was unlikely, but I wanted to veriify cause I have been known to be wrong.... The Aussie also was saying that $175 isn't cheap. I wonder if he actually owns a M100????? Thats real cheap as these cars go.

Did you sell you 6.3 yet?

Fred

[Emmerich]

Gerry, they have 3 colors marked on the spheres, red green and blue. Rustys web site says red is for front and blue for back. I replaced mine and I *thought* they were green, but I don't remember. Do you know where the proper color goes?

Fred

[gerryvz]

I didn't sell my 6.3, but it is for sale. You can see the car at: http://homepage.mac.com/gerryvz/PhotoAlbum13.html

I do believe the rear spheres are blue and not green, but I'll have to ask my parts friends to make sure and I'll update this if I am wrong on that. I need to call a friend today who will know, so I'll ask him the question.

I am sure that just about anything mechanical is technically rebuildable. But, you have to source and then adapt the proper materials (which can either be easy or hard to do, depending on what it is) and then perform the actual rebuilding. How many people have tanks of N2 on hand to "recharge" their spheres they are rebuilding? Again, you can get it, but how often would you need it? Lemförder is the OEM for the spheres.

I think it is possible, but not PROBABLE, to rebuild a sphere yourself. Because it's improbable, the vast majority of people would never even try it. In fact, in 9 years in the MB enthusiast community I have yet to learn of anyone who actually HAS rebuilt their spheres.

Lastly, if someone thinks $175 a pop is an expensive part for an M-100 car, they are sadly mistaken. This is cheap. That being said, a total suspension revamp for a 6.9 is an expensive proposition. Especially compared to a 6.3. My biggest complaint with M-100 owners or prospective M-100 owners is that they are among the cheapest bastards on the planet. Nobody wants to pay up front to get a decent car; instead these misinformed owners continue to purchase (effectively) rolling parts cars with the mistaken idea that they can "fix them up" cheaply. Nothing is farther from the truth or reality.

My 6.3 has been for sale for a year and a half now, $18,000. I just put over $5,000 into it a year ago for all new hoses, suspension and drivetrain rubber, plus front shocks. I even replaced the mushroom bump stops on the front control arms. And the work was done right. I get a lot of people who get all hot and bothered once they see my web page, to see a mechanically perfect, well maintained ORIGINAL 57,000 mile car. They send me notes, wanting to know how much I want for the car. These people are expecting me to say $7,000 or something like that. Unfortunately (for them) I never hear back from them when I quote them $18,000. They would rather purchase a $7K eBay car and suffer the debilitating costs of throwing part after part onto the rustbucket they just purchased. Unfortunately these people will never know the joy of driving and owning a proper 6.3.

Actually, I'm going to create a "typical M-100 owner life-cycle" document and post it on this site. It will detail the endless downward spiral of neglect that M-100 cars have to suffer through, in their succession of (cheap bastard) owners.....

Cheers,
Gerry

[Emmerich]

You are right on all counts. I just bought a 6.3. In very good shape, came with a clean bill of health from a mechanic, who it turns out didn't know much about 6.3's. When I checked it out the cosmetics were what sold me (perfect). Had a leak of some sort, so I knew I was in for some repairs. I drove it 800 miles home with no trouble. I went in with eyes open and it is in the shop now. My biggest problem was finding a qualified shop here in Dallas that can work on the car. I have it in Houston at my old wrench who I trust 100%. Luckily the tranny is in fine shape and not leaking. Unfortunately I had to have the injection pump rebuilt (shop here told me it was fine). Also had to do all new air bags, the shop here who did them missed the leaking air line... I am also doing a timing chain as a PM item. I am also changing to a Sanden a/c compressor but sticking with R12. It should be sweet when done.

I have been hunting a shop for some 6.9 work. I had an oil leak. Shop says it is a rear main seal. They say tranny removal is needed to change the seal. WOuld have been nice if that was the correct fix, but you have to pull the engine and crank on a 6.9. Supposedly allMB's of that vintage are like that, they should have known that. Tunrs out to be a leaking oil hose, which they had rebuilt previously.

I have been to 2 shops and I am 0-2. The one guy here who is highly recommended doesn't work on 6.3's, he MIGHT work on the 6.9.

[gerryvz]

In addition to deep pockets, having a qualified mechanic is a must with an M-100. Unfortunately there are very few who can do this work.

MBI here in Portland has a full-time M-100 mechanic on staff. On Friday there was a 600 and a 6.3 in the shop; generally there's always at least one M-100 being worked on at any given time. I guess most locales don't have the local M-100 base as Portland does, to support a knowledgeable mechanic.

How life in/with the M-100 Group these days?

Cheers,
Gerry

[Emmerich]

Seems pretty calm. Seems like a lot of posts are coming from Australians.

I missed the St Louis show, I wish I had gone. This year its in Charleston SC. IAMO seems to not be gaining much ground, I hate to see that happen.

[gerryvz]

IAMO is dead, 100% dead. It seemed that when push came to shove, nobody wanted to step up and lead. Brad and the others have dropped off the face of the planet. I think Brad has just gotten out of the whole M-100 scene and is just enjoying showing his cars.

Dan Smith tells me that things are changing with the M-100 Group. If I still have my 6.3, and if the current leadership does change and the group begins to take a more member-focused approach (and begins to provide some new benefits to members, instead of taking your $50 and sending you 3-4 newsletters of dubious value per year), puts some new programs in place, I'd consider re-joining and getting involved again.

From what I have seen, though, little seems to happen/change. I don't visit the "official" or "Riegler" web sites but I do answer M-100 questions here and also on the IAMO site at www.m-100.info.

Meanwhile, I'm having a ball with the other MB clubs and sites that I am involved in, and none of them seem to have even 5% of the politics that the International M-100 Group seems to engender. I'm still trying to figure this out, two-plus years after the fact. All I can say, is that the tone and culture of an organization stems from its leadership -- those at the top. I would say this applies to car clubs as well.

The IAMO had lots of potential, but nobody seemed motivated to help make it succeed. Another flaw in the M-100 world -- "sit on duff" disease. Sure don't see it in the SEC and the 500E communities.

Cheers,
Gerry

[j9fd3s]

imo, car events/clubs are supposed to be fun. if it takes bringing an rx7 to a miata meet, or a 300sel to an rx7 meet, then so be it as long as its fun.

mike

[gerryvz]

No arguments here !!!

Cheers,
Gerry

[Emmerich]

I have my fingers crossed that when M-100 finally changes for the better, them and the IAMO can join and share resources.

Here is an interesting link on spheres:

http://www.buromeca.fr/index_anglais.htm

Still seems stupid since all of this work is based on "membranes in good shape", If the membranes were in good shape the N2 wouldn't have leaked out in the first place.

Fred

[gerryvz]

Originally Posted by Emmerich

I have my fingers crossed that when M-100 finally changes for the better, them and the IAMO can join and share resources.

This will never happen as long as the current leadership of the IMG is in place. You don't understand, these people HATE (and I mean H-A-T-E) anything that has to do with me, that I have touched, or accomplished.

I sent a complete set of my reproduction 6.3 wheel emergency blocks (the metal stands as well as the rubber blocks) to Karl Middelhauve, a donation worth around $400-500 of my own money, to use as a door price or raffle item for the 2003 M-100 Meet. These were returned to me some months later with the note that Stu Hammel did not accept them and that they were strongly refused.

You know it's pretty bad (and people really hate your guts) when you send a goodwill/peace offering (no strings attached) in the form of a VERY valued item which is no longer available from Benz, which 99% of 6.3 owners don't have and would never hope to see, and it is refused because of who it came from. If the membership attending that Meet had known that this item had been received and then refused because it came from me, there would have been a revolt. But this was conveniently kept from the member base. Peter Kelly was quite upset when he found this out after the fact.

I hear a lot from Peter and Dan Smith about all of this impending change and goodness, but don't see a heck of a lot of action.

It's pretty funny to me that nobody at M-100 has ever come within 5% of offering the type of archives to the members that IAMO has on its site. This is the type of reference that many (if not most) car clubs provide to their members. If you go to sites such as the Chrysler Imperial Club, the 300 Adenauer Group, 300SE.org, and many other sites, you of course will see this type of thing. IMG is happy to take your annual $50, send you a few newsletters, put up a website, put on an annual meet (which you pay $300+ additional for) and then talk about how much value they're providing members. And this just continues, on and on, year after year, and nobody seems to say or do anything about it. A couple of new members here in Portland (including the guy who bought my 6.9 and attended the 2004 meet) have already told me that they have no plans to renew their memberships due to lack of value and actual INFORMATION that helps them maintain their 6.9 and 600 respectively.

I'm just kind of observing from afar, but I don't hold up much hope because I don't see any seeming vision or desire for change from the leaders at IMG. It's always sad to see somethign with great potential (IMG or IAMO) go down the drain.

Cheers,
Gerry

[gerryvz]

Originally Posted by Emmerich

Here is an interesting link on spheres:

http://www.buromeca.fr/index_anglais.htm

Still seems stupid since all of this work is based on "membranes in good shape", If the membranes were in good shape the N2 wouldn't have leaked out in the first place.

Fred

I agree -- something would have caused the internal metal membrane (or diaphragm as some people call it) to lose the charge of N2. Often these get bent or otherwise the seal fails due to use/wear (as they are constantly flexing due to the motions of the car).

Recharging the N2 would be a stopgap measure at best -- perhaps it would work for a short period of time (weeks or months at best).

My philosophy is to just replace with a fresh part when "wear" or "friction" parts are involved. I mean, would you "reline" brake pads or "retread" tires, or just go out and buy new ones? I'd buy new ones myself. Yes it's probably 50% more money, but at least you have a guarantee that it works.

Again this "rebuild every last part" type of mentality is endemic to individuals who really have no right driving the M-100 or 6.9 cars in the first place. If your tendency is to "cheap out" by trying to patch-fix every wear part that goes bad, you're gonna have a jalopy on your hands before you know it.

Of course many mechanical (non-friction) parts such as water pump, hydraulic piston pump, radiator, suspension valves, etc. are completely and fully rebuildable. But these are more mechanical than straight "friction wear" types of devices. And the parts (typically sealing rings, impellers and the like) are easy to find.

So it goes.

Cheers,
Gerry

[jcyuhn]

Jumping in here a bit late. By "rebuild" maybe he meant "recharge." The common failure mode of the spheres is for the high pressure nitrogen to diffuse out. Occasionally the membrane fails catastrophically. At that point the sphere is definately junk.

Citroens commonly use an oil over gas suspension at all four corners. In that world it's apparently common to just re-gas the spheres. Apparently some of them even have fittings to simplify doing so.

Many years ago when considering purchase of a 6.9 (I got over it...) I found a business that would modify the Mercedes spheres to attach fittings and re-gas them. I can't recall the cost, but it was dirt cheap - maybe $20/each? Their primary business was Citroen, but they were willing to dabble in other brands as well.

That said, I agree with the general sentiment here. For the price of a new set of spheres, just replace them all every ten years, and enjoy the ride.

- JimY