Can someone please briefly explain the difference between ABC and Airmatic with ABC?

W4SIM

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This might be abit of novice question but im confused as different models come with sort of suspensions with different settings and different issues but all the terms used for them seem to be the same.

The one thing i have learned is that the ABC system is quite prone to failure and very expensive to repair. But sometimes iv read its filled with hydraulic oil, others its full of air, so i just want to know what what really.

The car im looking at buying is a 2003-2005 S55K. Im sure thats got airmatic, but its also got the ABC button on it aswell. At the same time people are saying that CL500/600's of the same era have ABC which is unreliable!!!

Anyone care to break this down for me? Do both systems run alike? And are they both quite unreliable as each other or is the air one any better?

Thanks.
 

grober

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As I understand it the early S class had plain Airmatic suspension= air suspension with switchable ride heights-----to complicate matters it had an ABC [automatic body control ] option at extra cost. The sportier models SL and CL came with a hydraulic system with adjustable ride height but with active control [ ABC] as standard. To complicate matters I think the latest S Class is Airmatic with ABC as standard.--- there may also be several revisions/ versions of ABC also
 

st4

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Airmatic is simple air suspension, you use it to adjut ride height and firmness.

ABC is an oil filled strut that prevents body control. ABC struts do fail, and it costs about a grand to replace them.
 
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W4SIM

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Thanks for that chaps, getting somewhere.

So what exactly does the Airmatic S Class have that also has the ABC button aswell? Is that air suspension with a hydraulic strut in the middle or does the firmness get controlled by another means???

I have read the ABC systems are about a grand per corner when they fail, so wondering what the case is with airmatics? Or is it the same?
 

grober

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In both cases the suspension units are expensive to replace. Compressors on the early airmatic cars often burned out being asked to run for prolonged periods due to system leaks or electronic faults and were expensive to replace
 

prprandall51

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You get Airmatic OR ABC. Never both.

Whilst I am aware that there is a complex, expensive system under the name "ABC" fitted on some high-end cars, I am fairly certain that when I spec'ed Airmatic on my 2005 E-Class it was described as "airmatic with ABC(Active Body Control)" claiming that the suspension was semi-active, which, in practice, it is.

I don't have an "ABC" button in my car but I do have Comfort > Sport 1 > Sport 2" settings on a button. I thought that S-classes of the same era had the same set-up?
 

prprandall51

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Apologies, I have just looked it up and it was "Airmatic DC with ADS II" - how could I have forgotten that slick name?
 

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You have airmatic DC. Duel control. Sport one and two. It is a semi-active system when fitted to all 4 corners.

ABC is a hydraulic system and is very different.
 

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I just doubted my reply too! I dont like being wrong either.

I did the airmatic and ABC training courses a few years back and I can remember most of it!!
 
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W4SIM

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You get Airmatic OR ABC. Never both.

I recently went to view a 2003 S55K a month ro so ago and i asked the guy which suspension it had, Airmatic or ABC . . . . he said it had BOTH!!!! :doh:

When i went to see the car, it had the Airmatic, which went up and down via a button inside. But on the dash there was a button marked "ABC Sports". To be honest thats where most of my confusion arises from, as i also thought the same car would not have both. :confused:
 

grober

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This from Mercedes press release on the S CLASS. Which indicates Olly is pretty much spot on :thumb:.

MB S-Class In Depth
Text and photos coutesy Daimler Chrysler AG
09-03-2002


Suspension:
High-tech systems incorporate new refinements

AIRMATIC with second automatic lowering stage at high speeds
Active Body Control automatically adapts to vehicle weight

The S-Class owes its outstanding ride quality above all to the standard-fitted AIRMATIC system, which combines air suspension with the Adaptive Damping System (ADS) . The flagship Mercedes model range has been blazing a trail with this suspension ever since its world debut in autumn 1998. Now other luxury-class saloons are following suit with air sus-pension systems of their own.

For the model year 2003, AIRMATIC now incorporates further refinements. The speed-sensitive automatic body lowering system now adapts even more precisely to driving style and comprises two separate stages:

In "comfort" mode the body is lowered by ten millimetres at speeds over 120 km/h and then by a further ten millimetres at speeds over 160 km/h. The previous suspension levels are restored when the speed drops back under 75 and 60 km/h respectively.

In "sport" mode the lowering stages are activated earlier, at speeds over 110 and 150 km/h respectively. The previous suspension levels are restored when the speed falls below 70 and 55 km/h.

Measurement of current vehicle weight while on the move

Active Body Control (ABC) , the active suspension system pioneered by Mercedes-Benz, will incorporate additional functions as from autumn 2002 designed to further enhance both ride comfort and vehicle dynamics. For the first time it features a new load-adaptive design which measures vehicle weight, and uses it as a further control parameter for the active suspension. The weight is continuously calculated on the basis of the suspension travel recorded by the ABC computer while the vehicle is on the move. Control algorithms are then activated which compensate for the greater bouncing and pitching movements of the body at higher payloads.

If the vehicle weight changes, for example because luggage has been removed from the boot, or because a passenger has left the vehicle, the suspension characteristics are recalculated on the basis of the new payload.

All S-Class models fitted with the modified ABC system are weighed when they leave the assembly line at the Mercedes plant in Sindelfingen. This vehicle-specific unladen weight is then stored in the ABC control unit where it provides the basis for all subsequent calculations.

The load-adaptive feature significantly reduces body roll when the vehicle is fully laden and ensures that even at higher payloads, the vehicle dynamics of the S-Class remain the same as when the boot is empty.

Active Body Control is optionally available for models S 400 CDI, S 430 and S 500; it is standard equipment on the S 600.


AND

Technical glossary:
Important innovations in the S-Class

Active Body Control (ABC)

The active suspension system Active Body Control, developed by Mercedes-Benz, resolves the traditional conflict between active safety, responsive handling and ride comfort and is thus an important landmark in passenger car design. Using high-pressure hydraulic servos, an ingenious sensor system and high-performance microprocessors, ABC adapts the suspension and damping to different driving situations. The computer-controlled hydraulic servos or "plungers", which are mounted in the spring struts between the coil springs and the body, develop additional forces which act on the suspension and damping to control body motion. ABC is designed to control body vibrations in the frequency range up to 5 Hz - the kind of vibrations typically caused by uneven road surfaces or by braking and cornering. To control the higher-frequency wheel vibrations, passive gas-pressure shock absorbers and coil springs are used, which can be tuned for high ride quality. ABC virtually eliminates body movements when moving off from rest, when cornering and when braking. Cornering roll on S-Class models equipped with ABC is significantly reduced and there are also safety advantages in high-speed evasive manoeuvres compared with cars with conventional suspension systems. A press of a button on the centre console allows drivers to choose between comfortable or sporty suspension settings.

Adaptive Damping System (ADS)

The standard-specification AIRMATIC suspension system of the S-Class combines pneumatic suspension with an Adaptive Damping System (ADS), which adjusts the front and rear shock absorber forces to the current payload, the condition of the road surface and driving style. A steering angle sensor, three acceleration sensors on the car body, the ABS speed sensor and the brake pedal sensor constantly measure the lateral and longitudinal acceleration of the body. From this data, the ADS control unit calculates the optimal damper setting for each individual wheel and transmits the relevant signals with split-second speed to special valves on the gas-pressure shock absorbers. These valves are able to switch between four different damping characteristics. Using a selector on the instrument panel, the driver can also switch between a standard mode or a tauter, more sporty mode. This adjusts the thresholds at which the different damping characteristics are activated. In sporty mode, the firmest characteristic is selected earlier, while in comfort mode the softest characteristic remains activated for longer.

AIRMATIC

Instead of a conventional suspension and damping system with coil springs and gas-pressure shock absorbers, the new S-class is equipped with AIRMATIC, a system which combines pneumatic suspension with the Adaptive Damping System (ADS) to ensure a uniformly comfortable ride and high standards of active safety. AIRMATIC comprises a variety of components which are connected via pneumatic lines and CAN databus (Controller Area Network), namely pneumatic suspension struts front and rear, an air compressor, a central reservoir, air suspension valves, a control unit and various sensors. AIRMATIC is an open system in which the vehicle weight is supported by the compressed air enclosed in the rubber bellows of the suspension struts. Level control is effected by supplying or releasing air as and when required at each individual wheel, by means of fast acting solenoid valves. The necessary data for controlling the valves is supplied by two yaw sensors on the front axle and one on the rear axle, which monitor the level of the vehicle. The air suspension of the S-class not only automatically compensates for different payloads but also enables the vehicle level to be raised manually by 25 millimetres at the touch of a button on the instrument panel. This function is particularly useful when driving over dirt tracks, or badly potholed roads.
 

Melk63

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I have ABC on my current CL600 and also had it on previous CL55k AMG. I sware by it (and at it at times). It is astonishing how it keeps the two ton car absolutely flat through corners at any speed and yet it give a very supple and comfortable ride other times. The best ride of any car I have been in. The sport botton on the dash further firms up the suspension. The system is adjustable (by experts with right kit I suppose) and was set up slightly more sporty on the AMG. The system uses hydraulic struts that are constantly pumped by pulses of pressure from main hyd. pump. The control unit monitors body roll and directs hydraulic oil to the struts via control valves. Very effective but all the parts are made with extremely tight tolerances working under very high hydraulic pressures. This makes them somewhat unreliable and damn expensive. Overall a very high price to pay, but there aren't many other ways to keep the monster flat round a hairy bend. Mel.
 

reflexboy

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This makes them somewhat unreliable and damn expensive. Overall a very high price to pay, but there aren't many other ways to keep the monster flat round a hairy bend. Mel.
Agreed-Already had my 'monster bill' for a new valve block. That said, it really does work well in the corners.
 

biturbo

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well arnold industries does £600 struts with lifetime garantee.
Thing with ABC is once one thing goes it can then knacker many.
ie leaking strut, then causes pump to work too hard then that fails send rubbish through system and nails the valve block. So you end up with horror story bills.
ABC part numbers have more than one many of the items. I take it these are the better newer designers. The newer designed ABC components are far superior and very reliable.
One of the main reasons for problems, ( i spoke to guy from arnold industries) is the struts rubbish cheap rubber that was on the struts. They used to start to break up with age and use and then once that happens it causes extra stress on the strut which then cracks and new strut and if unlucky lots of bit of the abc system.
ABC is troublesome from mercedes until they sorted it out on later w221 models which i think you can use the same parts on the w220, or buy abc components from people like arnold industies.
 

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