ABC to Coilover or Airmatic

[195910]

Hello Everyone,

Looking at a V12 S-Class with ABC. System is functioning but I would like to look at alternative options such as Coilovers or Airmatic for when (not if) the system fails.
Anyone with experience in such conversions? I would like to know the driving characteristics and disadvantages of such conversions.
I would think the conversion to Airmatic would be possible and maintains the driving characteristics, but I haven't seen such a conversion done.

Thanks in Advance.

 

[maw1124]

No one is happy with those conversions. And an ABC failure is not a fait accompli, speaking from owning an ABC car and watching people consider, debate, and execute on this exact issue for almost 15 years. Every noob comes in thinking ABC is trash and they want coilovers, and every pro tells them otherwise. Some bite the bullet and coil over to their regret. Others simply learn to maintain the system. New fluid, dampers and sensors are usually the maintenance items, an occasional hose if those others have been truly neglected. Look for a car with fluid and dampers changed periodically.

maw

 

[gsxr]

@LWB250 may have some input on this.

My $0.02... buy a car that doesn't have ABC if you don't want ABC.

 

[alabbasi]

If it doesn't have issues , perform some preventative maintenance and you should be okay. Coil over kits are expensive in their own right and you can get a lot of ABC stuff fixed for what it would cost to convert the system.

 

[daantjie]

Often overlooked with "complex" systems like the HPF system on the 6.9 is that regular use and fluid/filter change is the best way to keep these systems in ship shape. If they sit the trouble and bills to fix start racking up...

 

[maw1124]

Often overlooked with "complex" systems like the HPF system on the 6.9 is that regular use and fluid/filter change is the best way to keep these systems in ship shape. If they sit the trouble and bills to fix start racking up...

Correct. The problem is you absolutely CANNOT play catchup on these cars. Well you can, but you won't enjoy it. So you have to buy one that hasn't been "neglected" -- which is a tricky word because MB originally spec'd these as NSI (No Service Interval) systems. Of course the fluid and filters need changing (same for the NSI transmissions), so that poor spec led a lot of these cars down the wrong road. I got mine at 38XXX miles in '09 so I haven't had any of the problems the forums scream about when they bought the run down example in 2019.

maw

 

[195910]

Gentlemen, this is why I ask this question here and not on any other forum. Respect!

Thank you for all the input, It is a sophisticated system and dealerships/workshops just repair the affected components rather than the cause.

My Concern is spare parts availability "NLA". System components can be rebuilt, but I heard the pump and some hoses are not available.
1 - Any issues with sourcing such components?
2 - Hoses (about 13 hoses?) internally disintegrate and contaminate the fluid, but is that with none maintained systems?
3 - With proper maintenance, should I still expect components such as the pump and valve blocks to fail but after an extended service life?

On the plus side, the struts don't fail due to worn bellows like the Airmatic, so it should be robust in rough road conditions just like the SLS on the W140 and W124. The strut bushing is also replaceable!

 

[maw1124]

eBay sellers I can show you do a great job with these components. Because the components have the rep they do, eBay sellers are all over making a business out of keeping them. "AutoHubShop" is one of my go to guys. With proper maintenance, the dampers will still be 100k maintenance items. The pump shouldn't go bad ever, and unless the system has been pumping sludge on old dampers, the lines should be fine. The MBWorld forum for W220/W221 AMG cars is active and has this all well chronicled. I'm active there as well for the S55. Valve blocks, I'm 50/50 on, but people rebuild them as a service so you can always get one. People report o-ring failure, but since hydraulic fluid cleans as well as lubricates, I'm not so sure. I haven't had any problems.

maw

EDIT... I just realized you're in Europe. I'm told the European dealers didn't get the NSI directive, so those cars have generally had the fluid and filters changed in both the ABC and the transmissions every 3/30. If that's the case on any car you buy, I don't think you should expect trouble. But do change the dampers. They're all due by now.

 

[Alphasud40]

When I purchased seals from a company in Germany for my R129 I thought they also offered a rebuild service for the hydraulic struts on the W140 cars. I will look again and forward the website. Good to know there are companies who have stepped up to offer a rebuild service to keep these great cars original.

 

[alabbasi]

The hoses are the most challenging of problems. They can be rebuilt by any shop that specializes in hydraulic equipment like fork lifts and farm machinery (they remove the ends and attach to a new house). The challenge is routing and removal and replacement can be a laborious job. The other parts can be expensive to buy, but not hard to replace.

 

[195910]

eBay sellers I can show you do a great job with these components. Because the components have the rep they do, eBay sellers are all over making a business out of keeping them. "AutoHubShop" is one of my go to guys. With proper maintenance, the dampers will still be 100k maintenance items. The pump shouldn't go bad ever, and unless the system has been pumping sludge on old dampers, the lines should be fine. The MBWorld forum for W220/W221 AMG cars is active and has this all well chronicled. I'm active there as well for the S55. Valve blocks, I'm 50/50 on, but people rebuild them as a service so you can always get one. People report o-ring failure, but since hydraulic fluid cleans as well as lubricates, I'm not so sure. I haven't had any problems.

maw

EDIT... I just realized you're in Europe. I'm told the European dealers didn't get the NSI directive, so those cars have generally had the fluid and filters changed in both the ABC and the transmissions every 3/30. If that's the case on any car you buy, I don't think you should expect trouble. But do change the dampers. They're all due by now.

Thank you for the input, BTW I am looking at a W220 S600 with full MB history! By now the entire system should have been renewed at least once, so I am certain it has updated system components.

Its the same issue in Europe. AT, power steering and ABC were "non serviceable".
I will need to see recent invoices or other forms of documentation for the Fluid and dampers. Else I need to take this into consideration for the cost.

 

[Alphasud40]

I followed this repair a while back with this YouTuber on the trials of bringing back a neglected ABC suspension. This former Mercedes trained tech was schooled and taught the ABC’s of ABC

 

[Alphasud40]

Here is that company in Germany that has R129 top seals and other hydraulic items. No listings for W140 though. My memory failed me.

RSC-Autotechnik

shop.rscauto.de

 

[195910]

I followed this repair a while back with this YouTuber on the trials of bringing back a neglected ABC suspension. This former Mercedes trained tech was schooled and taught the ABC’s of ABC

Not the most scientific approach. According to ABC specialists in Europe, Valve blocks can leak internally but after the pump shut off. Could it be the solenoids not wired correctly thus not actuating? Why were the struts not bled ?

"For safety reasons, the suction throttle valve on the ABC pump is closed again and again to reduce pressure in order to prevent further damage"

He left the pump running with low pressure for minutes! if there is air in the pump then the last thing you want is to run the pump for several minutes causing internal wear and low pressure. There should be another method to bleed the pump before starting the car.

I don't think the car is really "fixed"

 

[maw1124]

Not the most scientific approach... There should be another method to bleed the pump before starting the car.

I'm pretty sure this is what the rodeo procedure does -- min to max at all 4 corners exercising the pressure relief valves to expel air. ABC is best left to experts with the proper equipment.

Anyone can do anything for DaGram or YouTube but what about driving that car with their family in it for the next five years off camera?

maw

 

[Alphasud40]

I remember one of the root causes to the failure to pressurize after repairs was debris from a ruptured accumulator. I think besides annual fluid changes I would certainly be considering new accumulators every 5 years. Like Citroen these are wear items. Just like SLS on the W124 and W126 cars it’s better to replace proactively than to wait for the nitrogen to rupture through the bladder.

 

[LWB250]

Wow!

As the owner of a 2001 CL600 (W215) I am well acquainted with ABC. Nearly every aspect of it has been previously addressed, so I'll add what little I can:

1.) "Coilover" conversions are possible, but rarely done "properly", because it's not just a matter of replacing the struts with the coilovers. ABC provides all aspects of suspension, so if you take it away, not only do you have to replace the struts, but you have to install sway bars, too. That requires the replacement of the lower control arms at all four corners with W220 LCAs, because the ABC-equipped car has no provision for sway bar attachment because they're not used.

2.) Fluid! The hydraulic fluid in ABC is its lifeblood, literally. One thing I found when researching my car was that despite all the scary stories about ABC and how expensive/complex it is, one of the keys to trouble-free operation and longevity was regular (5,000-10,000 mile) fluid and filter changes. The clearances in the ABC system are tiny, and the pressures (200 bar) are great, so as seals and accumulator bladders break down those little microscopic pieces float around and can potentially damage the system. The only approved fluid is either the factory MB fluid or Pentosin CHF 11S. Nothing else!

3.) Regular maintenance, as in a fluid flush and multiple filter changes. Return line in a 5-gallon bucket, fresh fluid poured in as the level goes down while the system is alternately raised and lowered with DAS commands or with the ABC buttons in the cabin. When 10 liters have been flushed, level up, replace the filter, then perform the infamous "rodeo test". This alternately raises and lowers each corner of the car, one corner at a time, to test the system and circulate fluid. When the test is over, replace the filter again. This assures that any dirt or foreign material that might have been "shaken loose" during the rodeo test will be in that filter. Replacing it removes any crud and a fresh filter assures the new fluid will stay clean.

Is all this effort and concern worth it? Initially, I didn't think so. However, after a few sessions of driving the car quite aggressively, I can say that it absolutely, positively is worth it! You get lots of "smiles to the miles" in your 500Es - the feeling is mutual in my CL600. That and the ability to be cruising along at 80 mph and push the accelerator down to find there's plenty more where that came from...

Dan

 

[195910]

Quickly comparing ABC to SLS; both are Hydraulic systems with many similar components such as a tandem pump, fluid reservoir, nitrogen filled pressure spheres, struts and control valves. ABC uses a synthetic CHF11S fluid which is more advance than the mineral ZHM used in the SLS, and has an extended service life.

With exception to replacing the spheres after +10 years, the SLS system remained maintenance free for +20 years! My observation is that the SLS is simpler, operates at lower pressure (any idea what the pressure is??) and has NO rubber hoses. The spheres do rupture and I had this on 2 cars, yet it does not cause a huge mess like in the ABC. My understanding now is that the high operating pressure and rubber component attribute to the higher fail rate, and debris from internally failing hoses, dampers and torn O-rings clogg the valves and contaminate the fluid.

Another example is the W100 Hydraulic amenities system ( now a $100K system! ) which has a similar issue to ABC, but naturally we expect the valve block design and rubber technology to have greatly improved since this system was designed 60 years ago.

 

[195910]

I thought of the following idea, would it be possible to convert the ABC hoses to pipes ? similar to the SLS system, this should reduce contamination. The ABC hoses are not moving so why were these not made as pipes?

 

[alabbasi]

No they have elaborate routing with many connections to valves and shocks that would require flex during R&R and also from vibration. For context, I got rear ended in my S55 once and it broke the canister pulsation damper that's connected to the ABC pump