FAQ

What is air suspension in motor vehicles?

What is the principle of air suspension?

Air suspension whit air springs replaces steel coil springs as the load-bearing element in the suspension of a car. Traditionally, with most car suspensions, the weight of the car is supported by metal coil springs. In high-end modern cars, gas springs, also known as air springs, are used instead of metal coil springs. The carrier element is a rubber sleeve filled with pressurized air. Through complex control, the air springs are filled with air from an air compressor or are deflated, depending on what level of the car needs to be maintained.

Advantages of air suspension:

High level of comfort – the air spring has almost no internal tension leading to resonance and vibration for the damper to contend with. The stiffness of the air spring depends on the air pressure in it.
Improved road safety – thanks to the reduced tilting when turning, sagging when braking, etc. a car with such a suspension is noticeably safer and more stable, even with an increased own mass.
Constant level with different loads – the vehicle remains the same height regardless of how loaded it is. This is of great importance for its stability and safety while on the road.
Adjusting the level of the car – by changing the air pressure, the height (clearance) of the car can be changed. Thus, the car is automatically (or at the driver’s desire) adequately high for different terrains and driving conditions.

Disadvantages of air suspension:

High price – Quality comes at a price. Modern air suspension is a complex system consisting of many components. Electronic control, compressor, distributor, level sensors, electronically adjustable shock absorbers, etc. . The cost of four metal springs is nothing compared to everything described above.
Limited life and need for maintenance – no matter how high-quality the performance of the entire system is, failure still occurs. Metal springs are practically eternal (unless they break from overload), unlike air suspension. Let’s not ignore the fact that the bearing element is rubber that ages and cracks over time, and the entire complexity of the system entails opportunities for defects. All this requires professional care and prevention after a certain period of operation.
In case of breakdown, you are left stranded on the road – If the air suspension is damaged, the car “lies” on the ground, that is, its height relative to the road is only a few centimeters, making it almost impossible to move. Getting roadside assistance is also highly complicated (scratched door sills and bumpers are not uncommon).

What is the essence of air struts?

Nature of adaptive dampers.

Each shock absorber has a range of operation, that is, the ability to absorb energy. This range can also be called the operating characteristics of the shock absorber. These characteristics can be represented graphically by reading the graph to see how it performs in terms of bound and rebound. The characteristics of the shock absorber are static and are determined by the execution and adjustment of the hydraulic valves and bypasses inside it. When designing and setting up a traditional (passive) shock absorber, the manufacturer looks for the maximum compromise between comfort and behavior on the road and at different loads and speeds. Let’s mention a few basic points.

Change in the mass of the car – When the car is empty, the shock absorber does its job well. However, when it is loaded and becomes heavier, the same shock absorber with the same settings and characteristics must do more work and absorb more energy. A compromise is sought here somewhere in the middle.
Speed difference – When we drive slowly, the shock absorber should be soft enough to be comfortable, but when we are at a high speed, it should be hard enough to keep the car safe. Here, too, a compromise is sought in terms of comfort and security

The traditional (passive) shock absorber is one big awkward compromise.

All the disadvantages described above are eliminated with adaptive shock absorbers. The adaptive shock absorber, also known as an electric or semi-active shock absorber, makes no compromises between comfort and safety. It is essentially a normal hydraulic shock absorber, but it has a complex system of electric bypass valves, which instantly changes its performance. Its operating characteristics are floating according to the needs of the car. In other words, the adaptive damper can stiffen and soften instantly when needed. It is a rather expensive and complex item with the following advantages:

Unsurpassed comfort – At low speed it is soft enough to provide comfort for all passengers, while at high speed it hardens.
Operation adjusted to the mass of the car – When we load the vehicle, the adaptive shock absorber changes its operation to be adequate to the increased weight. In extreme cases, when, for example, a SUV tows a trailer with a large boat, everything is under control 🙂 .
It adjusts itself to the level /height/ of the car – In most cases, adaptive dampers work together with air springs. Thus, the driver can determine the comfort and level of the car. When the level of the car increases, its stability deteriorates sharply. This is compensated by the adaptive damper.
Adapts to the terrain through which it is driven – Being electronically adjustable, the adaptive suspension can automatically (or at the driver’s desire) change its response to the road. Offroad, city driving, highway or even “Bulgarian roads” 🙂 . There are systems that even scan the pavement in front of the car and react predictably to any pothole that is ahead (for example: Mercedes-Benz’s MagicBodyControl)
Improves braking and cornering behavior – When we brake sharply, the front shock absorbers prevent the “sinking” of the front, which ensures maximum traction on all wheels. Thus, the braking distance is drastically reduced. The same applies to cornering behavior where roll and stability can be controlled.

Regrettably, adaptive dampers are only found in the highest class of cars due to their high cost.

The adaptive suspension is a unique extra of the high-class cars, which the owners rarely realize and appreciate.

What problems can be encountered with air/adaptive suspension?

Air suspension is a complex system in which various defects can occur. Without going into details, we will list some of them.

1, Damage to or problems with the air springs – In most cases, the rubber sleeve bursts, as a result of which the air spring becomes non-functional. At other times, air leakage is observed through certain sealing rods, although the rubber sleeve may be intact. Common causes of air spring failure are:

Damaged dust cover – If the dust cover is torn, missing or damaged, fine dust and small stones fall into the area where the rubber sleeve rubs. As a result, the rubber wears quickly and cracks.
Wear and tear/Aging – Rubber ages over time, losing many of its qualities. After years of continuous use, friction and even in a wide temperature range, the rubber sleeve loses its elasticity and cracks easily.
Shock absorbers out of gear – The job of shock absorbers is to absorb sudden shocks. That’s where their English name “Shock Absorber” comes from. When the shock absorbers are not working, all the shocks and loads are absorbed by the air springs, resulting in a failure.
Hydraulic oil from a faulty shock absorber – One of the most common causes of air spring failure lies in the shock absorber. Over time, any shock absorber (no matter how good it is) breaks down and begins to leak a little oil. This oil gets into the cushion and damages it..AirTec offers impeccable repair of all adaptive shock absorbers, sparing you such problems!
Air compressor not working properly – The compressor’s job is to get pressurized air into the air spring…..just air, no moisture, no oil, no junk, etc. It often happens that a faulty compressor gets all kinds of crap into the air spring, shortening its life.
Damaged seals and rods – The air spring in combination with an adaptive damper makes up the so-called “air strut”. Depending on the implementation, different gaskets or sealing mounts are used between the air spring and the adaptive shock absorber. If these parts are damaged, the air spring starts to yield.
Corrosion of metal parts – Although rare, there have been failures due to severely corroded metal parts of the air spring as well as corroded steel rings.

2. Problems with the adaptive dampers – The shock absorber is a part working under extreme load and extreme conditions. The most common problems with them are:

loss of oil – Over time, the oil seals wear out and the shock absorber “leaks”. As a result of the loss of oil, it does not function properly.
breaking the guide – There comes a moment when the shock absorber breaks and starts rattling, rapping, etc. There is always a loss of oil during such breaking. The most common component that breaks is the guide that positions the rod relative to the body of the shock absorber.
damage or clogging of valves – the piston, bypass and valve block inside the shock absorber are extremely sensitive to clogging and dirt. When a valve becomes clogged, blocked or damaged, the entire shock stops functioning, even though everything appears to be working fine at first glance. It has oil, it doesn’t leak, it doesn’t rattle, it has enough gas, BUT it doesn’t work at all 🙂 . Such things are easy to detect at our test bench.
lack of gas – ALL shock absorbers contain oil and gas. That some are sold as “gas” is just a marketing ploy. If the gas in the shock is reduced, it leads to incorrect operation, oil cavitation and other problems.
Coca-Cola 🙂 – when the gas and oil in the shock absorber are mixed, a carbonated oil resembling Coca Cola results the same in taste, color, smell and hydraulic properties). It often happens when the oil seal of the separator is damaged in single-tube shock absorbers.
Oil cavitation

Why choose AirTec ?

In the conditions of a market economy and open markets, the consumer is overwhelmed with all kinds of offers. In the car service sector and in particular regarding “adaptive (air) suspension repair”, it is almost impossible for any end user to sift out the good companies with quality products. Many dishonest marketers advertise things they don’t actually have. We will list a few of our benefits that everyone should think about before undertaking a suspension repair.

Original OEM rubber – Unlike most companies that use NO-Name rubber, with us ALL air springs are repaired with original OEM rubber. Premium quality is guaranteed only at AirTec!
Our own computer-controlled hydraulic press UNIFLEX Hydraulik – Our own Uniflex industrial hydraulic press with PFM (Pressure Force Monitoring) and PFC (Pressure Force Control). Thanks to these functions, errors in the crimping of air springs are automatically eliminated. Uniflex Hydraulik gmbh are unmatched worldwide and are the only manufacturer of crimping machines used and certified by air suspension manufacturers. There are almost no such presses anywhere in Bulgaria, because unfortunately they are extremely expensive. Some of our competitors supposedly have Uniflex, but in fact they use Chinese presses massively, where the final effect is always a matter of great luck.You can read more about the press in the Service Section.
Our own computer-controlled dynamometric shock absorber test bench – We have a super modern computer-controlled dynamometric bench for testing, adjusting and calibrating all kinds of shock absorbers. With its help, we can carry out a thorough analysis of the condition of the shock absorber, as well as guarantee absolute repeatability of the results of the repairs carried out. An investment that makes the services we offer unparalleled in Bulgaria.
Original spare parts – We use parts from leading European manufacturers. Most components have optimized features, surpassing the quality and reliability of the originally built-in ones. In some cases, parts are produced specifically for us and our needs. Most companies are simply resellers of the big players in the market. With us, everything comes directly from the manufacturer! You don’t have to wait and pay middlemen! We have everything we need in stock to be able to react immediately!
Our own car repair facility – assembly and diagnostics – With us, the whole circle is closed. You don’t have to take your dampers off at some local garage and then personally take them to the recycling facility (let’s not forget you don’t have a car). With high-quality installation, we exclude the possibility of damage due to incorrect assembly (something that most of our competitors like to use as an excuse). We take care of all this, thus saving you time, nerves and money! With proper computer diagnostics, we are able to pinpoint the problem and in many cases prevent unnecessary expensive repairs. AirTec is housed in its own industrial building (1000 sq.m! built-up area and 10 decares of yard), meeting all European requirements. With us, you will not find yourself in a shed, a garage, a van, a basement or anything like that. You will find a trusted partner in us!
Qualified personnel and quality certificate – our manpower is our greatest pride. Through continuous training in Bulgaria and abroad, we constantly maintain a high level of service. We have a young, trained and reliable team that works in compliance with an established quality control system and in accordance with our clearly defined company values.
Flexible working hours – We work when you rest because we know that’s when it’s convenient for you to pay attention to your car.
Thousands of satisfied clients – AirTec is part of Adler Auto, an established brand in the automobile industry in Bulgaria. Everyone knows nowadays how hard it is to build a good image and how easy it is to ruin it. Our good name is the thing we are most proud of and with which we win customers from all over Bulgaria! Take a survey of how many people have been satisfied with our work over the years and you will see for yourself that we put all our energy into quality service for each individual client. The company philosophy and values with which we build our reputation find full application in our products!

What are the advantages of the rubber used in AirTec?

What is the difference between a new ORIGINAL air/adaptive shock absorber and a recycled one at AirTec?

The first association that comes to mind when we hear the word recycling or repair is related to breathing a little more life into something old, fixing it for a little longer, saving money at the expense of quality and reliability. This association is completely wrong 🙂 . After repairing the adaptive (air) shock absorber, you get even higher quality than the original!

After being repaired at AirTec, your adaptive (air) shock absorber is technically and visually indistinguishable from a brand new original one, and in fact even improved in many aspects. Why this is so, we will briefly describe in a few points:

1. Test of a computer-controlled dynamometric test bench for correct operation – Thanks to the test bench, we check all the functionality and operation of the repaired shock absorber. We test it at different speeds and loads, as well as over the entire operating range of electronic curing. The results are compiled into a computer graph, which we compare with the graph of a brand new original shock absorber. In this way, we are 100% sure that the repaired shock absorber works exactly the same as a new original one. That is, there is NO functional difference!

2. New hydraulic oil – during the repair, all the hydraulic oil in the shock absorber is replaced. We use original oil with the manufacturer’s characteristics. A guarantee for the same comfort and longevity.

3. Gasification – each shock absorber is filled with such gas and in such a way that the composition, quantity and pressure are identical to the original ones.

4. Electronic damping system – the entire electronic damper adjustment system remains original and fully functional. Regardless of the damper system, ADS, CDCE, CDCI, CVSA, EDC, DampTronic Sky, SDC, everything remains operational after our intervention!

5. Length and shape – since the original shock-absorber body is used, all dimensions, weight, grip are original. There is no visual difference.

6. Air spring crimping process – the air spring crimping process is absolutely repeatable and all parameters are monitored and controlled during pressing. Force and deformation rate are measured and controlled by the PFM (Pressure Force Monitoring) and PFC (Pressure Force Control) systems on our Uniflex press. These are features only available at Uniflex and thanks to them we provide a press that is proven to be identical to the one used in the factory. Crimping dimensions are achieved with an accuracy of one hundredth of a millimeter.

7. Dimensions and shape of the air spring – When repairing the air spring, the original parts are used and only the rubber and rings are replaced. The dimensions and shape of all parts are identical to the original ones. All kinds of gaskets, mounts, seals, sleeves, aluminum covers, etc. , which we replace are also identical to the original ones. Thus we eliminate any functional and visual difference.

Some of the advantages of the repaired parts as over the original new ones include:

1. Quality of the rubber sleeve – In the repair, we use premium rubber for greater strength and life.

2. Quality rings of the airspring – the steel rings with which the rubber sleeve is pressed must be made of a material resistant to corrosion and external conditions. Most models of original sleeves use quality stainless rings. In an effort to optimize costs, however, there are models of original sleeves where the rings corrode badly and problems arise. With us, these problems “planned by the manufacturer” are eliminated.

3. Optimized guides and seals – in some shock absorbers we use parts that remove “manufacturer-planned” defects. They use improved semi-rings with a longer life, guides made of reinforced materials that do not break so easily (in some Bilstein models they originally built aluminum guides 😉 ), optimized separators and a polished gas chamber for the separator and much more. Any one of these small improvements will save you a lot of headaches.

Why repairing the original when there are cheap NEW Chinese substitutes?

The eternal dilemma every consumer faces is whether to repair the original parts or get a cheap aftermarket replacement?

With a normal Golf or Clio, we could afford it, but with a car with adaptive suspension, it’s a complete disaster! There are countless tempting bargains on the market at extremely low prices. Most are from European or American companies, which, however, manufacture in one the same place in China. In some cases, the price of a NEW air strut (with included air spring) can be lower than the repair price of the original one! Many of these products are sold as European parts, but careful research always leads to the same factory in China 🙂

On the surface, these products look like the original ones, but after a test on a test bench or in a car, you can see that they are DANGEROUS! We will list some of the reasons, so that you can draw your own conclusions.

1. The quality of the Chinese airspring – in order to achieve a lower, more competitive price, a compromise is made with the quality of the air spring. A rubber sleeve is used, which is easily torn, or outright nursts under a sudden load. Corrosive rings are used, which either clamp the rubber too gently or cut through it due to excessive pressing. The metal parts to which the tire is pressed are thin-walled (weak) and do not allow good pressing, because they yield under pressure. Chinese air springs cannot be recycled!

Now imagine how a limousine weighing 2.5 tons, full of luggage and 4 people inside is moving at 220-250 km/h on our national “smooth” highways and suddenly the front right sleeve bursts! (feels as if a wheel has come off)

When you use cheap suspension parts, you don’t save money, you compromise your safety!

2. System for electronic adjustment of the stiffness of the shock absorber – ONLY the original shock absorbers have a working stiffening system! Chinese products have a socket that attaches to the car, but it only ‘fools’ the car so that a light on the dashboard does not light up. A “trick-toy” is placed on the shock absorber, and as a result the car ‘thinks’ it has a perfectly operational electronically adjustable shock absorber. When you drive fast or with a load, the car’s computer automatically stiffens the original shock absorbers to make the car stable enough. With the Chinese shock absorber, this does not happen (the car does not register it as an error because of the trick-gadget) and the result is dangerous instability in critical situations.

Unfortunately, you notice this when it is already too late, that is, in a situation where the Chinese suspension has betrayed you!

3. Outdated and inadequate shock absorber technology – Chinese (pseudo-European and pseudo-American) shock absorbers use technology found in low-end cars from the 70s (yes, it sounds far-fetched and many of you will not believe it, but just see for yourself). In general, it relies on a dual-tube design with parts copied from the VW Golf I. You’re probably reading this and thinking “hey, they got carried away with criticising the Chinese”, but we’re ready to open any Chinese Mercedes ML W164 or W166 shock you provide and compare the parts to the Golf I! (we’re not kidding) Extremely small piston, weak and small rebound spring, lack of calibrators and almost no resistance during operation. With the shock dynamometer, one can compare what resistance the Chinese aftermarket shock absorber can produce and compare it to that of a new original. The recorded results show that it is dangerous to drive with such a shock absorber!

4. Lack of comfort – the problem with the parts built into these shock absorbers is also evident in terms of comfort. The problem is in the lack of bypass and “GOLF I” technology. In reality, it turns out that at low load and speed the shock absorber is too hard (lack of bypass or incorrect one), and at high load and speed it is too soft.

That is, this new Chinese shock absorber (with European or American packaging) does its job exactly the other way around.

5. Aftermarket shock absorber (cheap replacement for original) CANNOT be repaired, improved or recycled!

Here, it might be appropriate to make a concession for the people who are happy with the Chinese parts because they have replaced the totally collapsed original (rattling) shock absorber with a new Chinese one. Usually the argument is that “it doesn’t rattle anymore” 🙂 The shock absorber’s task is not only “not to rattle”, but also to do its job. If a person has bought the car with damaged shock absorbers, and then replaced them with Chinese ones, it would be difficult for them to make a difference, because they have never driven with a working adaptive suspension before. Therefore, they are happy that although the car fails to provide comfort when driving, at least it ‘doesn’t rattle).

You have to decide for yourselves what to opt for – a shiny Chinese poor-quality product or a high-quality repair of the original part;) !

How do I know I have a problem with the suspension of my motor vehicle?

Usually, one only thinks about repairing their adaptive/air suspension when a total failure occurs or the car is left on the road waiting for roadside assistance. In most cases, you can tell in advance that there is a problem with the suspension or an impending breakdown, and it is good to seek expert help in time.

1. The car “squats” after a long stay – after a long stay, your car has taken a “German shepherd” position 🙂 or has completely lain down centimeters from the ground – this means that it is leaking air somewhere. After the engine runs for some time, the vehicle restores its horizontal position. Air leakage is possible in many places in the system. In this case, you should consider inspection and repair.

2. The car lay down or leaned sharply to one side while in motion and cannot restore its horizontal position – there are many possibilities here. Damaged air spring, defective compressor, defective level sensor, defective distributor, etc. In such cases, it is usually impossible to continue moving and repairs are inevitable.

3. The air compressor runs almost continuously – when there is a slight air leak, the compressor tries to compensate by running longer. This leads to premature wear of the compressor. In another scenario, the compressor is already damaged and is running at a lower flow rate, meaning it needs to run longer to deliver the required amount of air. It is advisable in such cases to think about inspection and repair before you are stuck on the road.

4. Visible shock absorber oiling – when a shock absorber is seriously damaged, it starts leaking a lot of oil. This oil quickly damages the air spring rubber and it rattles. If oiling is detected, it is absolutely imperative to consider preventive repairs.

5. Subtle rapping and rattling in the shock absorber – when the shock absorber is in the initial stages of breaking down, a slight rapping noise is heard at low speed, driving on cobblestones or going over potholes, bumps and ‘sleeping policemen’. Over time, this noise gets louder and in some cases feels like a broken front end. A common problem, for example, with the Audi A8 is such a strange and inexplicable noise when driving slowly over bumps, although all the mounts, joints and bialets are new. Damper noise is due to breakdown and loss of gas and oil, created vacuum or blocked bottom valve. In such cases, external oiling is not observed because the loss of oil is insignificant and it remains in the air spring, damaging it. Soon after, the air spring starts giving out rattling noises and leaves you stuck on your way. It’s okay when you need to keep it in mind and check things out in the near future

6. Thump when suddenly falling into a hole or dismounting from a speed bump – When the load is suddenly changed, the Bilstein Monotube shock absorber rattkes very strongly. This is best felt when you go at high speed over a ‘sleeping policeman’. Right on the way down from the sleeping policeman, when the tire falls down, a thump is heard. The same is the case when driving at high speed over a collapsed road surface and the tire drops sharply downwards. With this test you will easily check your shock absorbers.

7. Impaired cornering stability – high class cars usually have a powerful engine in addition to good suspension. This often predisposes to dynamic driving. When stability and handling deteriorate significantly, it is likely that the shock absorbers are leaking. In SUVs, there is a characteristic wobble to the sides, even though you are driving straight. The other very typical case is driving at high speed on a long, sustained turn. The rear of the car (especially in long limousines) starts to wobble quite dangerously. Instead of calmly and stably lying in the turn, the so-called “pumping” occurs, in which the rear rhythmically jumps. If you do not want to experiment with your safety, it is advisable to consider repairing the shock absorbers.

8. The dashboard light goes on and/or a suspension malfunction message is displayed – sometimes everything seems to be working perfectly, but still a warning light on the dashboard shows an adaptive suspension problem. In such cases, there is probably a problem with the electrical part (sensors, control or electronic hardening).

There are certainly many other symptoms of adaptive/air suspension failure. In any case, it is highly recommended that you seek help in time if you are in doubt.

Is there any point in preventive repair?

A person rarely decides to preventively repair their car until the damage has become too serious. In most cases, you think about air suspension repair and maintenance only when a breakdown occurs and the car remains on the road, that is, when the air strut collapses.

At the same time, you are used to the thumping, rattling and rocking of the broken shock absorber and do not plan to repair it (because no matter how broken it is, it will not leave you on the road). In the subsequent repair of the air spring, however, it is identified that the cause of the problem was the hydraulic oil from the leaking shock absorber. In such cases, the repair costs are not limited to the air spring, but the shock absorber also needs to be repaired.

All four “air shock absorbers” in your car are designed for the same life. They all do the same work, age the same, carry the same load (two by two) and travel the same path. In other words, all “air shock absorbers” are subject to the same depreciation, and if one of them fails, the rest will inevitably follow. When one of them is damaged, you have the choice of repairing only the damaged one or preventively fixing the rest as well. Damage to the “air shock absorber” is extremely unpleasant because:

1. It is extremely dangerous if it happens at high speed;

2. You remain stuck on the road and your only hope is the roadside assistance;

3. The car becomes so low that when you mount the roadside assistance, you inevitably damage the front bumper and apron, and this costs you more money and nerves;

4. You waste weeks waiting at paint shops until the damage caused by the roadside assistance is fixed;

5. Insurers won’t cover your paint damage because “it’s your own fault” that you didn’t seek specialized “spider” roadside assistance (never mind, there are a handful of them all over the country, and even if you look, you’re unlikely to find one)

All the costs described above exceed the total cost of preventive maintenance of your four “air struts” ! With a preventive repair of your adaptive/air suspension, you save money, time and nerves, because AirTec is not just a service, AirTec is a reliable partner who thinks about and cares for you!

Can I recycle the air spring only and use it afterwards with a damaged shock absorber?

What is the origin of the parts used by AirTec?

What about the prices?

Do you offer assembly/disassembly or do I have to bring the damaged part to you after removing it from the vehicle?

Do you offer partnership with other companies and/or service stations?

How do you guarantee and monitor the quality of each product?

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