Advantages and disadvantages of the ABC chassis?


  1. Advantages of the ABC chassis
  2. ABC maintenance-free, or not?
  3. Rust in the ABC chassis, why?
  4. Why is it so important to flush the ABC chassis and power steering system?
  5. Why is the maintenance of the ABC chassis so important?
  6. What is important when installing hydraulic pumps?
  7. Why do you change engine oil and transmission oil?

What are the advantages of the ABC landing gear?

From our point of view, the ABC chassis is a very innovative system from which we benefit. Increased driving safety and comfort by adapting the suspension and damping to the road surface and driving style. It has a significantly better vibration comfort than conventional chassis, furthermore reduced rolling and pitching movements of the body. Further advantages are lower vertical body movements due to road surface influences, lower air resistance and thus lower fuel consumption, and less lift on the front axle. But the most important advantages for us users are the raising of the vehicle level in 2 steps for bad road surfaces or garage entrances and the possibility of setting 2 maps for comfortable or sporty driving style.

Mercedes-Benz R 230 (2001-2011)
Mercedes-Benz R 230 (2001-2011)

Here is an overview of the buttons and display messages
with the S Class W220 and CL C215.

For European vehicles SL R230 and CL C215, the 1st level is raised +11 mm and the 2nd level +36 mm. In the S-Class W220, the 1st level is raised +25 mm and the 2nd level +50 mm.

An overview of the buttons and display messages on a SL R230.

For USA vehicles SL R230 and CL C215, the 1st level is raised +10 mm and the 2nd level + 20 mm. In the S-Class W220, the 1st level is raised by +20 mm and the 2nd level is +30 mm.

What goes up also goes down, the so-called automatic lowering depending on the speed driven. This is very important when the vehicle is lowered, which I do not believe in, because the suspension struts and handling are damaged. The European vehicles SL R230 and CL C215 drop continuously from 60 km / h to 140 km / h by -25 mm below normal level. The S-Class W220 only -15 mm.

What you should also know, regardless of the 1st or 2nd level you are driving, from 60 km / h the vehicle automatically returns to its normal level. If you then get faster, it will also drop below the normal level. If you slow down again, below 60 km / h and the level level is still selected, the chassis automatically returns to this increased level. So you could drive it to the highest level and everything will take care of itself. Oh, and by the way, those stupid forum entries "You break your ABC chassis if you always drive in the highest level" is the biggest nonsense. You should think about lowering your vehicle with adjustable coupling rods, because that destroys everything and worsens the driving behavior so that some people no longer have their vehicles under control. But more on that soon.

Is the ABC chassis maintenance-free or not?

Many people who drive such a vehicle or want to purchase a vehicle with ABC chassis are concerned with this question. Many customers always ask me, Mr. Zädow, hand on heart, is the ABC maintenance-free as Mercedes always says or not? From years of experience with this chassis, I can answer that with a clear no. But everyone can answer the question for themselves. If it were maintenance-free, we would not have had so much damage to the ABC chassis all over the world, it has always been a huge issue. The web and forums are full of worries and problems with this landing gear. But especially our tests and research work, as well as our statistics that we keep in our company, clearly show what damage a dirty system can result. In addition, there is incorrectly filled OIL or broken-down vehicles simply due to a lack of knowledge. In particular, the branches are unteachable, by replacing clean oil and filters, they think nothing at all. The oil smells burnt, pungent odor, and OIL is black as tar, yet you are installing expensive new parts there. If I were the mechanic I would be reluctant to install such a beautiful new part there, I would be sorry for the spare part and especially for the vehicle.

I think a vehicle is like it's a human body. If I didn't do something right or prescribe or prescribe something wrong, it could have fatal consequences. I'm a little different when it comes to vehicles anyway, the way others talk to plants or lay hands on, I have that with vehicles. With many vehicles, as far as Mercedes is concerned, I hear or feel what is missing while driving. You can laugh about it, but that's the truth. Customers have always been afraid of my diagnoses. The vehicles come directly from Mercedes or from TÜV, all without defects or the car is free of defects and I can still see and hear something. Localizing noises is very easy for me, but only marginally. In the near future I will be writing a book about working on Mercedes vehicles and especially the ABC chassis. Many customers have advised me to do this. One of our last customers, who is also in the Oldtimer Club, advised me to have all the knowledge I have in me to write down the vehicles with ABC chassis and the V8 and V12 engines from Mercedes for posterity. Thanks at this point for all the nice conversations and numerous visits this year. 

But back to the subject of maintenance-free or not, as mentioned before, all the experiences and damage to the components show us every day and although we have been reporting about it for over a decade, actually preaching, every 2nd vehicle with an original filter is 10 micrometers down Plant and black oil in the yard. Especially from Mercedes but also from other workshops. The vehicles have already installed new pumps or struts. Absolutely incomprehensible to me! There is a huge contradiction to what the master tells the customer, ABC chassis maintenance-free, and to what the mechanic is clearly advised by the Mercedes WIS program before starting work on the ABC chassis. I quote "During all work on the ABC chassis, extreme cleanliness must be ensured, as the smallest contamination and particles can lead to a total failure of the ABC system."

Now, of course, the question arises, why can dirt particles, dust grains and the like lead to total failure? The dirt that arises in the system itself, such as abrasion, chips and suspended particles as well as rubber sludge from the inner walls of the hydraulic hoses! Just think about it. But I have a huge collection of parts and pictures of ABC parts that suffered in contaminated systems. But really had to suffer. I'll show you a few pictures soon. And a picture is worth a thousand words. I think with the pictures that follow later, I have clearly answered the question. By the way, the aforementioned WIS program also contains clear work instructions for flushing or filtering the ABC system. The mechanic is obliged to check the oil quality and then has to make a decision. I'll add a couple of pictures to this too. By the way, the WIS program is the electronic repair guide from Mercedes. Everything is written there that a mechanic and foreman at Mercedes needs to know.

Rust in the ABC chassis, why?

Our next topic also answers the question with no when it comes to the maintenance-free ABC system. 200 km Mercedes-Benz service history and proof that Pentosin is hygroscopic. Rust in the ABC chassis system. As weird as it sounds, it really is. It starts a short time after filling and especially when the ABC system is in operation. Pentosin behaves in a similar way to brake fluid and has a similar chemical structure. Why do we change the brake fluid at regular intervals? As mentioned before, a picture is worth a thousand words.

Why is it so important to flush the ABC chassis and power steering system?

This is not our idea and it is not used to make money, as is often claimed. If a hydraulic pump, whether an ABC pump, servo pump or other hydraulic pump, is defective, it is either wear and tear due to driving performance or another defect on the component that also pulls chips with it. The parts in the hydraulic pumps move, the damage does not occur while standing, but when moving. Where do the chips go into the system, just like with wear. Wear means material abrasion, where does it stay in the OIL, i.e. everywhere in the system. Regardless of which hydraulic pumps are used, they are all extremely sensitive, especially the vane pumps of the power steering.

There is a study by LUK that not even 1 percent of the workshops in Europe flush and clean the power steering systems after replacing the pumps, regardless of whether the cause was wear or another defect. Every spare parts dealer is obliged to hand over these documents to the workshops and has done so for over 30 years. We have been doing it since that time. That's why we always recommend everyone to keep your oil systems clean, especially in the Mercedes SL R230 2001-2011, the model even lacks the servo filter.

All other vehicle models have a servo filter. Due to the additional production costs of the SL R230, there is no filtering in the steering system. There were then claims that the SL has a steering system that does not wear out, but it has the same system as the CL C215 and the S-Class W220, CLS and E-Class W211. These vehicles all have a filter, but even this filter does not filter 10 micrometers finely enough, you know it from the ABC area, where they switched to 2006 micrometers in 3 and that is still not enough.

With such important safety-relevant systems as the servo system and the ABC chassis there is such a slump and that at the expense of other components in the systems and also at the expense of the new parts that are installed. And don't forget, at the expense of customers and their wallets, you have to keep in mind that you have to keep opening your wallet. As mechanics, masters and engineers in automotive technology, we have a high level of responsibility, and we have been preached to this responsibility in our training, whether it is tightening wheels, changing axle parts, brakes or hydraulic technology. The engine and transmission are of secondary importance, they are not safety-relevant assemblies, but they are treated first. When it gets more complicated, most of them don't feel like it anymore.

But in an emergency, it is not the employees who are upset, but the boss of every company. Everyone think about it and find out who has ever flushed a steering system. Stop giving people wrong diagnoses and repair instructions that are definitely wrong, you sometimes make the damage a lot bigger than it might be. The people who believe you have much more damage as a result, we have had cases like this here.

Why is the maintenance of the ABC chassis so important?

The manufacturers advertise with the statement that the user of the vehicle does not have to change the oil in the hydraulic chassis once during the entire service life. 

"Maintenance-free" is the statement. In theory a beautiful thing, no cost. But that's only a nice thing at first glance, in practice it looks different. The cost comes with the aging of the oil. Every user should be aware that despite this statement by the vehicle manufacturer, deposits and residues will form. These can lead to considerable problems in the future, including defects in the hydraulic chassis. Problems with longer downtimes and the resulting costs can be the result. Therefore, an oil change should be carried out at regular intervals in order to maximize the life of the hydraulic components and thus also the driving pleasure. Careful maintenance of the hydraulic chassis has an absolutely positive effect on the components of the hydraulic chassis. 

Dirty oil
Dirty oil

A study that we carried out with an S 55 AMG compressor with a mileage of 470.000 km has shown that it makes sense to change the oil in the hydraulic chassis every 30.000 km in order to protect all components in the system from the liquid sandpaper. Because if there is an impurity in the system, the hydraulic oil turns into liquid sandpaper. The result is greater wear and tear, more friction (overheating of the hydraulic pump, which leads to cracking), damage to the running surfaces of the suspension struts and malfunctions of the control units. Added to this is the abrasion of the inner walls from the hydraulic hoses, which also turns the pentosin oil black and even makes it muddy, the so-called floating particles clog the holes and microsieves in the ABC components.

The tasks of a hydraulic oil include, among other things, the transmission of pressure to the individual chassis parts, absorption of forces, heat dissipation, lubrication and the operation of the hydraulic control. However, this requires a clean oil and it should not be too old. Because the prescribed hydraulic oil "Pentosin" is hygroscopic (it draws water from the humidity), the same phenomenon as changing the brake fluid every 1–2 years. The lifespan of the "Pentosin" oil is around 1,5-2 years in use. 

4–5 years in normal closed storage. By absorbing moisture from the air, you have the phenomenon that your components in the hydraulic chassis rust. With longer idle times, we have already had vehicles where the pistons in the hydraulic pump were rusted and a "red error message" came up when starting for the first time in spring, hydraulic pump total loss. 

Then there are the broken chips, which are immediately distributed in the system, so that a complete renovation of the system is necessary. The usual problems with which a hydraulic chassis has to struggle are often caused by the use of oil that is too old. 

Dirty oil
Dirty oil

Due to wear and tear, the viscosity cannot be 100 percent retained and optimal lubrication can no longer be guaranteed. In addition, dirt particles settle over the years due to the metallic abrasion and the floating particles that detach from the inner walls of the hydraulic hoses, which continue to make good lubrication impossible. In the worst case, this can even lead to blockages of the oil strainers or the hydraulic control units, making it impossible for the components to self-lubricate. The consequence is bearing damage.

Due to the insufficient lubrication, renewed abrasion can hardly be avoided. It is therefore a "vicious circle". This significantly shortens the service life of the components in the ABC / MBC hydraulic chassis. The harmful deposits caused by the abrasion can only be removed almost completely by changing the hydraulic oil, depending on the variant. A change should be made every 2–3 years, more precisely every 30 to 40.000 kilometers. In 2008 we developed the "Zädow Method" to make it possible for every user to change the oil in the system. The system's oil change is carried out by manually moving the undercarriage up and down, with new oil being filled into the reservoir and the old oil that is expelled via the return line being collected in a separate container. There are several options for flushing the system, including using a separate pump and using the Star Diagnosis.

With the “Zädow method”, however, we have shown many users and workshops a method to carry out an oil change in the ABC / MBC system without costly work equipment. For this purpose, we developed the magnetic filter in 2008, which on the one hand should serve as a separating point in the return, as a sight glass for the oil quality and the most important point, the magnet.

Why is there no magnet in the ABC chassis?

In every motor, in every gearbox, in every industrial plant where oil is involved, there are so-called collecting magnets. The collecting magnet is responsible for collecting any metallic abrasion so that it cannot wander around in the system and cause damage. 

Unfortunately, this collecting magnet does not exist in the hydraulic chassis systems. However, our study over the past 10 years has revealed a decisive design flaw in the ABC system. I have not published this until today. I always asked myself why the struts in the ABC system were the components that were most quickly affected by damage. The construction of the struts is to blame. The plunger travel sensor is located in the spring struts, which in turn requires the so-called position magnet in order to be able to do its work.

In the illustration below you can see how it works and you can also see the various magnetic fields that are necessary for this. However, these magnetic fields have a decisive negative effect, they collect any abrasion from the system and fix it to the piston rods of the strut, where it becomes a particularly damaging mixture. For this one reason we came up with the idea of ​​the magnetic filter to counteract this.

Structure of the shock absorber
Structure of the shock absorber (source: Mercedes Benz)

Our idea was to position the magnetic filter right in the pressure outlet of the hydraulic pump. To develop only a magnetic filter that could withstand an oil pressure of up to 300 bar was too expensive and not for sale on the open market. So I chose the return line in low pressure mode. This alone was the reason for the magnetic filter in the ABC system. The engineers recognized this and made a design change in 2004. Hydraulic suspension struts without plunger travel sensor and without magnetism and lo and behold, the suspension struts last longer and are no longer as badly damaged as those with magnets.

abc filter for mb chassis
The ABC magnetic filter

What is important when installing hydraulic pumps?

There is one more important thing to note: never crank hydraulic pumps empty or dry by hand or with the engine starting, this is the death of any hydraulic pump. On the high-gloss, lapped aluminum surfaces, which have a surface as smooth as glass, grooves and scratches occur when rotated dry, especially with vane pumps, which leads to a loss of performance or other damage to the pump. Furthermore, this is also not good for the plain bearings, even aluminum surfaces. So don't unpack and play around with it, but fill the pump with oil and then you can turn it and install it. Fill both areas of the ABC servo pumps. We would like to send all pumps pre-filled, but we are not allowed to. See shipping guidelines and environmental guidelines. I know the curiosity is great, new spare parts and turning it first, but it is completely wrong and dangerous. At Mercedes, I know, the pumps are pre-filled. So before you install the pumps do not turn them, remove the plugs, fill the ABC area of ​​the pump and then fill the servo area, then you can turn it. Put the plug back on and then install it and never disconnect the suction hoses and remove the container with the old oil and reinstall it, this is often routine in workshops, but fundamentally wrong. The sealing plugs do not let dust or dirt fall into them during installation, nobody does an engine wash beforehand and some vehicles look bad in the engine compartment. But even relatively clean vehicles have dirt, dust and sand everywhere in the engine compartment, which is normal. When working, no matter who is doing it, something can always come loose and fall into it. That is death for hydraulic systems.

Why do you change engine oil and transmission oil?

For more than a decade there was a dispute about changing gear oil at the friendly partner, until now gear oil change every 60 km has become mandatory at MB. Experience has shown that our gearboxes urgently need this. The ABC chassis works with 000 bar oil pressure, carries the whole vehicle and us with it. The attention that this landing gear needs is downplayed in many places, whether it is the workshops, branches or in the famous forums, or tries to refute it with insane remarks. The servo system is also completely disregarded, which is just as affected. "... rinse the servo system, what nonsense ..." we are told. Why do we have so much work? Increasing sales in 200 and 2017 worldwide with ABC hydraulic spare parts. We see it every day how necessary it is, but we don't know what that concerns, at least it is claimed in the forums and branches. From 2018 to 2007 I explained in an understandable way for every vehicle owner what to look out for with the ABC chassis before buying or even vehicles that are already in possession. Among other things, the oil check 2008 of the ABC hydraulic oil using the dipstick and a white cotton cloth. Then I came up with the Magnetic Filter 1.0 and brought it onto the market to create more transparency for the vehicle owner. After more than 1.0 years the problem is still the same. I came up with the new oil test 10 for 2019, a new magnetic filter 2.0 is coming, and our new ABC hydraulic oil is being used. Furthermore, we will set up a YouTube channel to show films of our experiences and the correct work sequences for ABC chassis, power steering systems, motors, transmissions, tips & tricks, and much more. m. to publish.